Geely MR479Q, MR481QA, JL481Q, MR479QA User Manual

Chapter 1 Engine Overview ......................................................................................................01

Section 1 Basic Structure and Working Principle of Engine. ......................................................................01

Section 2 Structural Characteristic of Engine .............................................................................................04

Section 3 Engine Technical Performance and Parameters ......................................................................12

Section 4 Engine Servicing Datasheet .......................................................................................................18

Section 5 Maintenance of Engine ...............................................................................................................23

Chapter 2 Cylinder Block Assembly ....................................................................................26

Section 1 Structural Characteristic of Cylinder Block ................................................................................26

Section 2 Detach, Assembly and Servicing of Cylinder Block ..................................................................27

Chapter 3 Cylinder Head Assembly ...................................................................................45

Section 1 Structural Characteristic of Cylinder Head ................................................................................45

Section 2 Detach, Assembly and Repair of Cylinder Head ......................................................................45

Chapter 4 Piston & Connecting Rod Mechanism ....................................................69

Section 1 Construction of Piston & Connecting Rod Mechanism ............................................................69

Section 2 Dismantling and Inspection of the Connecting-rod and its Bearing ......................................72

Section 3 Common Faults and Troubleshooting of the Piston Connecting-rod Mechanism ................73

Chapter 5 Crank Mechanism ..................................................................................................76

Section 1 Structural Characteristics of Crank Mechanism ........................................................................76

Section 2 Disassembly & Maintenance of Crank Mechanism ..................................................................78

Section 3 Common Faults and Troubleshooting of Crank Mechanism ...................................................83

Chapter 6 Valve Train ....................................................................................................................84

CONTENTS

Section 1 Make-up of Valve Train & its Design Features ............................................................................84

Section 2 Valve Timing ..................................................................................................................................85

Section 3 Make-up of Valve train Assembly and its Features ...................................................................86

Section 4 Service of Valve Train ...................................................................................................................89

Section 5 Common Faults and Troubleshooting of Valve train ................................................................93

Chapter 7 Fuel Supply System .................................................................................................94

Section 1 Makeup and Features of Fuel Supply System for Electronic Fuel Injection Engine ................94

Section 2 Matters Needing Attention in Use and Maintenance of Electronic Fuel Injection System....99

Section 3 Troubleshooting the Electronic Fuel Injection System .............................................................102

Section 4 Evaporative Emission & Positive Crankcase Ventilation Control System ..............................124

Chapter 8 Ignition System .........................................................................................................127

Section 1 Introduction to Ignition System ..................................................................................................127

Section 2 Troubleshooting of Ignition System ...........................................................................................128

Chapter 9 Lubrication System ...............................................................................................132

Section 1 Makeup and Features of Lubrication System ..........................................................................132

Section 2 Examination & Maintenance of Lubrication System ..............................................................136

Section 3 Common Faults and Troubleshooting of Lubrication System ................................................141

Chapter 10 Cooling System .....................................................................................................143

Section 1 Composition & Features of Cooling System ............................................................................143

Section 2 Inspection and Maintenance of Cooling System ...................................................................147

Section 3 Common Faults and Troubleshooting of Cooling System ......................................................149

Chapter 11 Clutch ..........................................................................................................................150

Section 1 Structure of Clutch and Its Operating Mechanism .................................................................150

Section 2 Clutch Troubleshooting ..............................................................................................................152

Section 3 Assembly and Adjustment of Clutch and its Operating Mechanism ...................................155

Section 4 Common Faults and Troubleshooting of Clutch .....................................................................158

Chapter 12 Common Faults and Troubleshooting of Engine ........................160

Section 1 Overview .....................................................................................................................................160

Section 2 Determination and Elimination of Common Faults in Engine ................................................160

Section 3 Determination and Elimination of Abnormal Noises in the Engine ........................................171

Chapter 13 Power source .........................................................................................................173

Section 1 Structure of Clutch and Its Operating Mechanism .................................................................173

Section 2 Battery ..........................................................................................................................................175

Section 3 Normal Malfunction of Charging System and Troubleshooting ............................................176

Chapter 14 Starter ..........................................................................................................................177

Section 1 Structure of Starter ......................................................................................................................177

Section 2 Working Principle of Starter ........................................................................................................178

Section 3 Attentions in Use of Starter .........................................................................................................178

Section 4 Troubleshooting of Starter ..........................................................................................................179

Chapter 15 Engine Management System ....................................................................180

Section 1 System Profile ..............................................................................................................................180

Section 2 System Composition and Working Principle ............................................................................181

Chapter 16 Engine Electronic Control System ..........................................................184

Section 1 General Structure of Engine Electronic Control System .........................................................184

Section 2 Structural Principle of the Components of the Engine Electronic Control System ..............184

Engine provides power to the automobile. Presently, internal combustion engine is widely applied in the automobile. It’s

a kind of thermal machine that can control the fuel combustion in the cylinder to generate heat energy effectively, and then

convert the heat energy into mechanical energy that drives the piston in the cylinder to make reciprocating movement as

the way to output the power by the connecting rod, the crankshaft and the flywheel. The automobile runs with the power

transferred by the internal combustion engine to the automobile driving mechanism. Most of the internal combustion

engines providing power to the automobile are gasoline or diesel engines based on the fuel for combustion. The power to

GEELY car comes from the gasoline engine equipped with the electronic fuel injection system. It’s made of the machine

unit, crank connecting rod mechanism, valve train, fuel supply system, ignition system, cooling system, lubricating system,

startup system and management system.

1. Machine Unit

The machine unit is mainly composed of cylinder head, cylinder block and oil pan. It’s the basis of assembling the

engine mechanisms and systems, and the base to support the engine in normal operation. In another word, many parts of

the machine unit have multiple specific functions. For example, the internal walls of cylinder block and cylinder head make

up the combustion room, but they are also the components of crankshaft connecting rod mechanism, fuel supply system,

cooling system and lubricating system. The machine unit is designed to bear ultra heat or mechanical load.

2. Crankshaft Connecting Rod Mechanism

The crankshaft connecting rod mechanism is composed of body, piston, connecting rod, crankshaft, flywheel and crank

shield. It converts the heat generated by engine combustion into mechanical energy, namely, converts the piston linear

reciprocating movement into the crankshaft and flywheel rotations, and then the flywheel outputs the power. The flywheel

is designed to keep the engine in stable rotation by the rotating inertia.

3. Intake Mechanism

The intake mechanism is composed of cylinder head, intake valve, exhaust valve, cam shaft, tappet, valve spring, cam

shaft timing gear, and timing belt. The intake mechanism is designed to open the intake valve in time, take in the combus-

tible gas mixture into the cylinder, and emit the post-combustion exhaust gas out of the cylinder in time.

4. Fuel Supply System

The fuel supply system is composed of gasoline pump, gasoline filter, gasoline distribution pipe, pressure regulator,

fuel injector, fuel tank, air filter, throttle body, intake manifold, exhaust manifold, exhaust gas purifier, and exhaust muffler.

The fuel supply system is designed to mix gasoline and air into high-quality combustible gas mixture, send it to the cylinder

for combustion, and emit the exhaust gas out of the engine.

5. Ignition System

The ignition system is composed of storage battery, engine, ignition coil, high-voltage wire and spark plug. The ignition

system is designed to make sure the compressed gas mixture to be ignited right at the preset moment. The ignition system is one

of the characteristics of gasoline engine to differentiate from the diesel engine.

Chapter 1 Engine Overview

I. Basic Structure of Engine

Section 1 Basic Structure and Working Principle of Engine

1

2

6. Cooling System

The cooling system is composed of pump, radiator, fan, water inlet and outlet pipes, thermostat, the drain valve of

cylinder, and the gas water cavity. The cooling system is designed to emit the thermal energy in the heated components

to the air, so that the engine can work under thermo-equilibrium with powerful, cost-effective, reliable and durable features.

7. Lubricating System

The lubricating system is composed of oil pan, oil collector and filter, oil pump, pressure limit pump, as well as oil

passage, oil filter, and oil gauge in the machine unit. The lubricating system is designed to transmit the lubricant onto the

working surfaces of components in relative motion, so as to have the surfaces lubricated, cooled, sealed, antirust-treated

and cleaned, and in this way guarantee a normal and reliable operation for the engine.

8. Startup System

The startup system is composed of startup motor and its accessories. It’s designed to start up the engine from statistic

mode to automatic operation.

9. Engine Management System

The engine management system is also called the engine control system. It’s composed of sensors that measure the

engine operation status and parameters, the Electronic Control Unit (ECU) and the controlled acting components.

The system is based on the Electronic Fuel Injection (EFI), with ECU controlling the Electronic Spark Advance (ESA)

and the Idle Speed Control (ISC) so that the engine works in optimal condition.

II. Operational Principle of Engine

Fig. 1 Working Principle of Engine

The engine works continuously to convert the heat generated by combustion into the mechanical energy. It never stops

repeating the 4 strokes in the cylinder, including intake stroke, compression stroke, power stroke and exhaust stroke.

Below is a description of an operational cycle of 4-stroke gasoline engine, taking a single-cylinder engine shown in Fig.

1 as an example.

Piston Stroke

TDC

BDC

3

An operational cycle of 4-stroke engine is made of the intake, compression, power and exhaust strokes. When the

piston moves from Top Dead Center (TDC) to the Bottom Dead Center (BDC), the crank turns 180°. The distance from

TDC to BDC is called piston stroke.

1. Intake Stroke

The intake stroke is the process of taking in the combustible gas mixture into the cylinder. The intake valve opens right

before the piston approaches the TDC, and the exhaust valve closes immediately after the piston goes down. The intake

and exhaust valves form a proper overlap angle when they’re open simultaneously, which helps emitting the exhaust gas

effectively and improving the scavenge quality with the gas inertia. As the piston goes down further, the gas capacity

expands to produce ultra vacuum in the cylinder, so more gas mixture is taken in. When the piston reaches the BDC, the

intake valve is still open. Till the piston goes up and more combustible gas mixture goes into the cylinder with inertia, the

intake valve will close after the crank turns to the proper delay angle.

If the operational capacity of cylinder is fixed, in order to enable the engine to produce more power, the gas mixture

shall be taken in as much as possible in the intake stroke. In this sense, multiple valves, turbine mid-air cooler and

electronic fuel injector are applied to produce more high-quality combustion gas mixture

2. Compression Stroke

The compression stroke is the process of compressing the combustible gas mixture in the cylinder. The piston goes up

from the BDC, with the intake and exhaust valves closed. The pressure and temperature of combustible gas mixture in the

cylinder increase rapidly, so the heat-atomized fuel and gas become more even that helps improving the combustion

quality and the power capability. As improving the compression pressure may result in certain danger, the compression

ratio shall be keep at the best level. Improving properly the engine compression ratio, i.e. the ratio of maximal cylinder

capacity vs post-compression minimal capacity, may make the engine more powerful and cost-effective.

3. Power Stroke

The power stroke is the process in that the combustible gas mixture burns and expands to generate power in the

cylinder. At this moment, the intake valve is still closed. Before the piston goes up the TDC, the temperature and pressure

of gas mixture increase a lot, which drives the ECU to select and figure out the best ignition timing, and then the spark plug

will generate spark to ignite the combustible gas mixture. The gas mixture burns and releases heat that makes the

temperature and pressure increase sharply in the cylinder, and the maximal pressure occurs at the crank angle of 10° to

20° after reaching TDC. When the piston goes down after reaching the TDC, the expansion-to-power process begins. The

piston drives the crank and flywheel rotating with the connecting rod, and outputs the driving torque. When the piston

reaches the BDC, the power stroke ends. In order to keep the engine more powerful, cost-effective and less-polluting, we

have made great efforts to improve the combustion, make full use of the fuel, and purify the exhaust gas, and we’ll go on

with the efforts

4. Exhaust Stroke

The exhaust stroke is the process of emitting exhaust gas out of the cylinder. Before the piston goes down to the BDC

in the power stroke, the exhaust valve opens, and the hot combustion gas turns to be exhaust gas after the expansion-to-

power process, and then begins to go out of the cylinder. The piston goes up after it reaches the BDC, and the exhaust gas

is extruded. Before the piston reaches the TDC, the intake valve begins to open for scavenge. Of course, when the piston

reaches the TDC, the exhaust valve will close after a period of delay.

The piston goes down from the TDC into a new operational cycle. With the operational cycles made up of the above-

mentioned 4 strokes, the engine works repeatedly and outputs non-stop power that drives the car forward

4

TStructural Characteristic of Engine Engine and Engine are new products based on the features

of domestic. overseas same type engine and the modern up-to-date engine technologies It applies the technologies of

electronic control fuel multipoint sequence injection, group ignition, and close-ring control system provided by the United

Automobile Electronic of Shanghai (UAES). The multipoint sequence injection guarantees that the combustible gas

mixtures are produced in different cylinders under identical conditions, so as to improve the mixture quality; the ECU

updates and selects the best injection timing, producing highly precise control of fuel quality. It’s structured without power

distributor and with 2 ignition coil that can generate voltage as high as 10 to 35kV for ignition.

With the overall displacement of and . engine and engine are cylinder-in-line,

water-cooling. 4-stroke gasoline engines equipped with double over head camshaft, 16 valve, and electronic control fuel

injection. There’re the oxygen sensor and the three-way catalytic converter in the exhaust pipe. ECU controls the switch of

cooling fan in the engine according to the change of cooling water temperature in order to keep the cooling water in normal

temperature. Fig. 2 and Fig. 3 are the assembly drawing and the components assembly drawing of engine. Fig.

4 and Fig. 5 are the assembly drawings of engine with power system and auxiliaries respectively.

Fig. 6 is the layout of electronic control fuel injection system in engine.

Fig. 2 Assembly Drawing of MR479Q/MR479QA Engine

Section 2 Structural Characteristic of Engine

MR481QA
IL481Q

1.342L

1.498L

1.587L

1.762L

MR479Q
MR479QA

MR481QA
JL481Q

MR479Q
MR479QA

MR479Q
MR479QA

MR479Q
MR479QA

5

Fig. 3 Components Assembly Drawing of MR479Q/MR479QA Engine

6

Fig. 4 MR479Q/MR479QA Engine and Its Power System

7

Fig. 5 Assembly Drawing of Engine and Its Auxiliaries

MR479Q

MR479QA

8

Fig. 6 Electronic Control Fuel Injection System in Engine

MR479Q

MR479QA

9

Fig. 7 Front view of Engine

JL481Q

MR481QA

10

Fig. 8 Sectional elevation of Engine

JL481Q

MR481QA

11

Fig. 9 Electronic Control Fuel Injection System in Engine

JL481Q

MR481QA

12

4-cylinder in line, water-cooling,

dual-roof convex shaft, 16 valves, belt

and gear driven, hip-shaped combustion chamber

78.7×69 78.7×77

1.342 1.498

9.3 9.8

800±50

Dynamic adjusted by ECD with the condition

0.20±0.05

0.30±0.05

63/6000 69/6000

110/5200 128/3400

≤259 ≤279

≤0.1

≤50

CO≤2.3g/Km,HC≤0.2g/Km,NOx≤0.15g/Km,with OBD

function

NO.93 or above Lead-free vehicle gasoline

Pressure and splash combined

SAE 10W-30 or SAE 10W- 40 SAE15W-40

SAE 5W-30 in frigid area, API quality rate: SG or above

≥90

294 ~539

3.5 (full in dry mode),3.1 (full in wetmode)

Force-cycle, water-cooling

0.8 ± 0.1

Type

Bore × stroke (mm × mm)

Displacement (L)

Compression ratio

Rotation at idle speed (r/min)

Ignition timing

Valve clearance Intake(mm)

(In cold state) Exhaust (mm)

maximum power (KW/r/min)

Maximal torque (N.m/r/min)

Minimal fuel consumption ratio at full load (g/kw.h)

Emission at idle speed CO (%)

HC (PPm)

Test cycle emission (GB

III

)

Number of fuel

Lubrication

Oil specification

Oil pressure Idle (kpa)

3,000r/min (kpa)

Oil capacity (L)

Cooling

Spark clearance (mm)

MR479Q MR479QA

Section 3 Engine Technical Performance and Parameters

1.Major Technical Parameters of MR479Q Engine and MR479QA Engine

13

Type

Bore × stroke (mm × mm)

Displacement (L)

Compression ratio

Rotation at idle speed (r/min)

Ignition timing

Valve clearance Intake(mm)

(In cold state) Exhaust (mm)

maximum power (KW/r/min)

Maximal torque (N.m/r/min)

Minimal fuel consumption ratio at full load (g/kw.h)

Emission at idle speed CO (%)

HC (PPm)

Number of fuel

Lubrication

Oil specification

Oil pressure Idle (kpa)

3,000r/min (kpa)

Oil capacity (L)

Cooling

Spark clearance (mm)

MR481QA JL481Q

II. Major Technical Parameters of MR481QA Engine and JL481Q Engine

4-cylinder in line, water-cooling, dual-roof convex shaft,

16 valves, belt and gear driven, hip-shaped combustion

81×77 81×85.5

1.587 1.762

9.6 9.6

800±50

Dynamic adjusted by ECD with the condition

0.20±0.05

0.30±0.05

78.7/6000 83.1/5600

137/4400 156.8/3400

≤269 ≤269

≤0.1

≤50

NO.93 or above Lead-free vehicle gasoline

Pressure and splash combined

SAE 10W-30 or SAE 10W-40. SAE15W-40.

SAE 5W-30 in frigid area. API quality rate: SG or above

≥90

294 to 539

3.5 (full in dry mode).3.1 (full in wet mode)

Force-cycle. water-cooling

1.0 ± 0.050

14

III. Engine performance curve

Engine feature refers to the rule in that the engine performance indicators change with the operational conditions. The

speed feature of engine is commonly used to define the rule in that the power, torque and fuel consumption ratio change

with the rotating speed in the case of fixed engine load (the throttle opening angle is fixed). The speed feature in the case

of full engine load (the throttle is completely opened) is called the exterior feature. The exterior feature curve describes the

maximal power, maximal torque, minimal specific fuel consumption of engine and the corresponding changes of engine

rotation speed, as shown in Fig. 10, Fig. 11, Fig. 12 and Fig. 13.

Fig. 10 Exterior Feature of MR479Q Engine

ge( g/kwh)

Rotation Speed

n r/min

Power

Me (N.m)

Torque

Pe(Kw)

Fuel Consumption Ratio

15

ge(g/kwh)

n

r/min

Power
Me (N.m)

Torque

Pe(Kw)

Fuel Consumption
Ratio

Rotation Speed

Fig. 11

Exterior Feature of MR479QA Engine

16

n r/min

ge(g/kwh)

Fuel Consumption

Ratio

Rotation Speed

Power
Me (N.m)

Torque

Pe(Kw)

Exterior Feature of MR481QA Engine

Fig. 12

17

Fig. 13 Exterior Feature of JL481Q Engine

Power
Me (N.m)

Torque

Pe(Kw)

ge(g/kwh)

Fuel Consumption
Ratio

18

Section 4 Engine Servicing Specifications

I.MR479Q/MR479QA/JL481Q/MR481QA Engine Servicing Technical Datasheet (Table 1 to Table 4)

Table 1 Mechanical Part of MR479Q/MR479QA/JL481Q/MR481QA Engine Servicing Datasheet

Servicing Data

0.030

0.050

0.080

0.080

0.100

1.000-1.400

1.000-1.400

45°

0.500

5- 23

1.000-1.400

45.5°±15’

5.960- 5.975

5.950

5.960-?5.975

5.950

0.800-1.200

0.500

0.800-1.200

0.500

0.025-0.058

0.080

0.025-0.058

0.080

39±0.30

38.570

31.700

160±8N

150

0.015-0.055

0.075

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Maximal correction

Standard

Allowed limit

Intake

Exhaust

Standard

Standard

Seat surface width

(mm)

Valve race surface angle

Intake bearing hole

Exhaust bearing hole

Standard

Lower surface flatness

(mm)

Flatness of manifold

interface (mm)

Valve seat

Allowed concave in valve seat surface (mm)

Standard value of cam

shaft bearing hole (mm)

Standard interface width

with valve seat (mm)

Taper angle

Outer diameter of

valve stem (mm)

Thickness of

valve seat edge

Clearance between valve

stem and valve

conduit (mm)

Valve spring

Valve tappet

Intake

Exhaust

Intake

Exhaust

Intake

Exhaust

Free height (mm)

Installation height(mm)

Installation load (N)

Allowed limit of perpendicularity(mm)

Oil film clearance

Cylinder head

Valve Valve

Valve

conduit

1- 25

+0.021
0

4- 23

+0.021
0

1.2

A

Name of item

φ

φ

φ

φ

φ

φ

φ

φ

φ

19

Exhaust cam shaft

0.040-0.091

0.110

Exhaust 42.01±0.04

Exhaust 41.850

Exhaust 42.01±0.04

Exhaust 41.850

0.030

0.035-0.072

0.120

0.035-0.072

0.120

0.040-0.091

0.120

0.020-0.200

0.300

8.75±0.03

8.6

0.040

0.050

78.730

81.03

0.0065

0.0065

0.040

0.040

0.075 – 0.095

0.115

79.115 - 79.145

79.315 - 79.345

81.445 – 81.485

81.645 – 81.685

I) 78.665- 78.655,II) 78.665 78.675

III) 78.675-78.685

I) 80.955- 80.965,II) 80.965- 80.975

III) 80.975-80.985

Intake cam shaft

0.032-0.085

0.110

Intake 41.76±0.04

Intake 41.650

Intake 42.665±0.04

Intake 42.554

0.030

0.040-0.082

0.120

0.040-0.082

0.120

0.032-0.085

0.120

MR479Q and

MR479QA

JL481Q and

MR481QA

Cam height (mm)

(Base circle + lift)

Clearance between

journal and

bearing(mm)

Cylinder bore (mm)

Piston skirt

dimension for

servicing (mm)

Skirt H=18,H=16

Diameter standard

Axle clearance (mm)

Name of item

Servicing data

Journal uneven abrasion (mm)

Thrust bearing clearance (mm)

Gear clearance (mm)

Upper surface flatness (mm)

Diameter of cylinder head bolt (mm)

Cylinder hole roundness (mm)

Cylinder hole perpendicularity (mm)

Cylinder hole dimension for

servicing (mm)

Clearance between piston skirt and

cylinder hole (mm)

MR479Q and

MR479QA

JL481Q and

MR481QA

MR479Q and

MR479QA

JL481Q and

MR481QA

1 to 2 for front

3 to 5 for middle

and rear

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Plus 0.5

Plus 0.7

Standard

Allowed limit

Plus 0.5

Plus 0.7

Plus 0.5

Plus 0.7

MR479Q and

MR479QA

JL481Q and

MR481QA

Camshaft Cylinder block Piston

78.700

+0.030

0

79.200

+0.030

0

79.400

+0.030

0

81.0

+0.030

0

φ

φ

φ

φ

φ

φ

φ

φ

φ

φ
φ

φ

φ
φ

φ
φ

φ

φ

φ

φ

φ

φ

φ

φ

φ

φ

20

Outer diameter (mm)

?20

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

Allowed limit

Standard

0.002-0.013

0.017-0.044

0.2-0.4

1.050 for 1 ring,1.200 for 2 ring

0.2-0.7

1.100

0.20-0.055

0.04

0.060-0.160

0.180

0.03

0.06

0.020-0.051

0.070

0.150-0.30

0.35

0.005

0.01

0.020

0.015-0.033

0.100

0.040-0.220

0.250

47.982 – 48.000

47.745 – 47.755

39.985 – 40.000

39.745 – 39.755

47.982 – 48

47.745 – 47.755

2.450-2.480

2.350

0.015

0.100

1.486 – 1.490

1.490 – 1.494

1.494 – 1.498

1.606 – 1.610

1.610 – 1.614

1.614 – 1.618

Central wall thickness of

connecting rod bearing shell (mm)

Clutch interface run-out (mm)

Thickness of thrust plate (mm)

Connecting rod journal

diameter(mm)

Master journal diameter (mm)

Axle clearance (mm)

Journal uneven abrasion (mm)

cylindricity

Clearance to ring

groove edge(mm)

Opening clearance (mm)

1 to 2 rings

Oil ring

1 to 2 rings

MR479Q
MR479QA
MR481QA

Oil ring

Interference with connecting rod (mm)

Clearance to piston (mm)

Allowed bend (per 100mm) (mm)

Allowed twist (per 100mm) (mm)

Axial clearance of connection

rod big end (mm)

Clearance between connecting rod bearing and

connecting rod journal(mm)

Clearance between master

journal and bearing (mm

Plus for servicing

JL481Q

Piston ringPiston Pin

Connecting rod Crankshaft Bearing shell

Flywheel

+0.016
+0.010

φ

φ

φ
φ

φ

φ φ

φ

φ

φ

φ

φ

21

Standard

Central wall thickness of

connecting rod bearing shell (mm)

Table 3 Fastening Torque Specifications of Major Bolts and Nuts in

Table 2 Main Adjusting Parameters for MR479Q/MR479QA/JL481Q/MR481QA Engine

Plus for servicing

2.002 – 2.005

2.005 – 2.008

2.008 – 2.011

2.011 – 2.014

2.014 – 2.017

2.122 – 2.125

2.125 – 2.128

2.128 – 2.131

2.131 – 2.134

2.134 – 2.137

Torque N.m

18

13

10.8

20

59

37

127

29

Rotation of 90°

Rotation of 90°

31

20

9.3

19

15

Quantity

4

22

4

2

1

1

1

10

3

2

1

7

2

Specification

M14 x 1.25 S=16

M6 x 40 S=10

M6 nut S=10

M8 x 31 S=12

M10 x 1.25 x 23 S=14

M10 x 1.25 x 40 S=10

M12 x 1.25 x 31 S=17

M10 x 1.25 x 90

Dodecagonal bolt S=10.3, e=11.5

M10 x 1.25 x 20 S=14

M8 x 12 S=12

M6 x 12 S=8

M8 x 30 S=12

M8 x 50 S=12

Part

Cylinder head

Cylinder head

Cylinder head

Cylinder head

Camshaft

Cylinder block

Crankshaft

Cylinder block

Cylinder block

Cylinder block

Cylinder head

Cylinder head

No.2 water inlet

Cylinder head

Intake manifold

Name

Spark plug

Cam bearing cover (bolt)

Cylinder head hood (bolt)

Ignition device

Camshaft timing belt wheel

Belt tension wheel

Crankshaft tension wheel

Cylinder head (1st screwing)

Cylinder head (2nd screwing

Cylinder head (3rd screwing)

Generator stand

No.2 water inlet

Oil position ruler conduit

Intake manifold

Transmit pipe

Adjusting parameter

Under pressure of 98N, deflection of 7 to 9mm for new

belt, and 11.5 to 13.5mm for used belt

Intake 0.20±0.05

Exhaust 0.30±0.05

0.8±0.1;1±0.05(MR481QA,JL481Q

800±50

At idle speed (rotation = 800±50r/min), 8±2° before

TDC (T terminal connected)

CO≤0.2%, HC≤60PPm (QB)

3.5L (full in dry), 3.1L (full in wet)

Oil level between F line and L line of ruler

Deflection is 5 to 6mm under pressure of 20N

Item

Tension of belts in generator and pump

Valve clearance (mm) (in cold state)

Spark plug clearance (mm)

Rotation at idle speed (r/min)

Ignition timing

Pollutant emission at idle speed

Oil capacity

Tension of timing belt

Bearing shell

22

Torque N.m

29

10.2

21

44

31

22

22

22

34

59

59

17

60

70

80

70

9.3

20

20

51

39

5.6

78/85

4.9

44

30

7±1

Quantity

2

2

1

1

1

2

1

2

5

1

1

4

10

10

10

8

6

1

3

3

2

2

6

19

1

1

2

2

Specification

M12 x 1.25 x 26 S=17

Flange hexagonal nut M6 S=8

M8 x 29 S=12

M8 x 16 S=12

M8

M8 x 54 S=12

M8 x 35 S=12

M8 x 16

M10 x 1.25 Nut S=14

M10 x 1.25 Nut S=14

M10 x 1.25 x 20 S=13

M6 x 12 S=10

M10 x 1.25 x 60 S=14

M10 x 1.25 x 60 S=14

M10 x 1.25 x 60 S=14

M9 x 1 S=14 e=16.2

M6 x 16 S=8

M8

M8 x 35 S=12

M10 x 1.25 x 35 S=13

M10 x 1.25 x 21 S=14

M6 x 13 S=8

M10 x 1.25 x 23 S=17

M6 x 12 S=8

M16 x 1.5

Substandard thread

M10 x 1.25 x 20

M6 x 40

Part

Transmit pipe

Intake manifold

Intake manifold

Cylinder block

Cylinder head

Intake manifold

Cylinder head

Cylinder head

Cylinder head

Exhaust manifold

Cylinder block

Exhaust manifold

Cylinder block

Cylinder block

Cylinder block

Connection rod body

Cylinder block

Cylinder block

Cylinder block

Cylinder block

Cylinder block

Cylinder block

Crankshaft

Cylinder block

Exhaust manifold

Cylinder block

Cylinder head

Regulator seat

Name

Fuel-in pipe

Cooling water bypass hose

Intake manifold seat

Intake manifold seat

Engine stand(RH)

Throttle section

Water inlet stand

Water outlet

Exhaust manifold

Exhaust manifold stand

Exhaust manifold stand

Heat-isolation cover of exhaust pipe

Rear oil seal ring

Knock sensor

Water Pump

Installation rack for RH engine

AC generator adjusting level

Rear end plate

Flywheel

Oil drip pan

Oxygen sensor

Oil filter

Front and rear hooks of

engine Idle regulator

MR479Q
MR479QA
MR481QA

1st screwing by hand.

2st wrenching 3/4 circles

MR479Q

MR479QA

JL481Q

Main bearing

cover

Connecting rod

cover

Connection

rod body

M9 x 1 S=14 e=16.2 8

65

JL481Q

MR481Q

23

In order to extend the engine life, the maintenance shall comply with the following procedures during its running.

1. Daily maintenance

a Check the gasoline, cooling water and oil levels, and add in if necessary.

b Remove the dust or spilled electrolyte on the storage batteries, so as to make sure that the ventilation hole is unblocked.

When the electrolyte is insufficient, add in the distilled water in time.

a Check the leakage of oil or water.

b Judge whether the engine runs properly after its startup through listening, and check the instrument operations.

2. Maintenance per 1,000km of driving

a Complete the daily maintenance.

b Check and adjust what are necessary.

c Check the electrolyte proportion or voltage of storage batteries.

d Check whether the connectors of ECU, generator, spark plug and other electrical accessories are loose.

A Check whether all parts of the gasoline engine are well fastened.

3. Maintenance per 5000km-drive

a Complete the maintenance per 1,000km of driving.

b Check whether the storage batteries develop crack or have electricity leakage.

c Check whether the generator works properly.

d Replace the oil.

4. Seasonal maintenance

a Add anti-freezer into coolant in the winter days.

b Adjust the concentration of storage battery electrolyte on seasonal basis.

1. Maintenance Periods and Maintenance Content

Section 5 Maintenance of Engine

Specification of applicable oil: SAE10W-30 or SAE10W-40, SAE15W-40: frigid zone: SAE5W-30. API grade: above SG.

1. Check whether the engine oil is in bad quality, mixed with water, fading or diluted.
Replace the oil in case the quality apparently deteriorates.

2. Check the oil level

The oil level shall be between L and F in the oil ruler 5 minutes after the engine stops working. If it’s too low, check the

leakage and add in oil to the mark F, but never above F.

3. Replace with new oil

Discharge the oil completely after it works for a period, and replace with the new oil. During the course of replacement,

discharge the used oil from the oil pan when the engine is still hot. If there’s a large quantity of impurities in the oil pan,

wash them out with light spindle oil, but never wash with gasoline or coal oil.

Clean the oil-filling port before injecting oil in it, so as to prevent the impurities from entering together. After adding in the

oil, wait for 5 minutes before checking the height of oil level. After the injection is completed, put on the cap.

II. Maintenance of Lubricating System

When the engine is running, there must be enough cooling water in the cooling system to make sure that the engine

works properly. Therefore, before each drive, the driver shall check and add in timely clean soft water, but is not allowed

to use the unprocessed hard water with high content of alkali or mineral substances.

There shall be no excess rust or furring on the radiator cover or around the water-filling hole of radiator. Mix the high-quality

glycol-based coolant according to the manufacture’s instruction (the recommended concentration is above 50%, but no

higher than 70%), and never use the ethanol-based coolant.

1. Check and Replacement of Timing belt

Check whether the belt is installed properly. If any belt gear tooth is broken or damaged, check whether the camshaft is

stuck; if there’s observable crack or damage on the belt surface, check the positions of belt pilot wheel and each belt wheel;

if the belt gear tooth wears apparently, check whether the timing belt cover is damaged, or installed improperly, or if any

alien substance exists on the belt gear tooth, and replace the belt if necessary. In normal case replace the belt after each

120,000km of driving.

Note: Don’t bend, twist or turn outwards the timing belt, and keep the timing belt off oil, water or vapor.

2. Check and Measurement of Valve Clearance

Note: Check and adjust the valve clearance when the engine is in cold state.

a Turn the crankshaft pulley to align the “V” groove on it to the timing mark “O” on the No.1 timing belt cover. Check

whether the mark “K” on the camshaft timing pulley is in line with the timing mark “U” on the bearing cover. If not, turn the

crankshaft a circle (360°).

b Measure the clearance between the 1, 2 cylinder intake cam and the 1, 3cylinder exhaust cam and the valve tappet with

the thickness meter, and make sure it comply with: 0.15 to 0.25mm for intake, and 0.25 to 0.35mm for exhaust.

c Turn the crankshaft pulley for a circle to align the “V” groove on it with the timing mark “O” on the No.1 timing belt cover.

Check and measure the clearance of 3. 4 cylinder intake valve and 2, 4 cylinder exhaust valve. In normal case, check and

adjust the valve clearance per 40, 000km (or 24 months).

3. Check of Pump Driving (V-type) Belt

III. Maintenance of Cooling System

IV. Check of Engine

Fig. 14 Tightness of water pump driving belt

Water pump

AC

98N

Crankshaft

Check the belt per 10,000km-drive (or 6 months), as follows:

(1) Check visually whether the driving belt groove over-wears, the

sennit looses, or the spoke is striped. Replace the belt if damage is

found.

(2) Impose the belt with the pressure of 98N (10Kgf), and make

sure the belt deflection ∆ is:

∆ = 7 to 9mm for new belt; and ∆ = 11.5 to 13.5mm for old belt.

If the deflection is not in compliance with the above standard,

adjust the belt tension (Fig.14). New belt refers to the belt that has

worked in the running engine for less than 5 minutes; Old belt

refers to the belt that has worked in the running engine for no less

than 5 minutes.

24

4. Replacement of Engine Oil

In normal case replace the engine oil per 5,000km of driving (or 3 months), and replace it per 2,500km of driving in

adverse conditions.

5. Replacement of Oil Filter

Remove the oil filter with the specialized servicing tools, and replace it per 10,000km of driving (or 6 months) in normal

case, and per 5,000km of driving (or 3 months) in adverse condition. Pay attention to the follows during the course of

replacement:

1. Check and clean the installation surface of oil filter.

(1) Check whether the component number of new oil filter is the same as that of the original one.

(2) Paste the clean engine oil upon the gasket of new oil filter.

(3) Screw in the oil filter gently, and screw it down when the gasket touches the base.

(4) Screw 3/4 rounds more with specialized servicing tools.

6. Check and replacement of spark plug

Check it per 10,000km of driving (or 6 months) in normal case, and replace it per 20,000km of driving (or 12 months).

(1) Check visually whether there’s electrode ablation or screw damage in the spark plug. Replace the spark plug if it’s

not in normal condition. The recommended spark plug is: MR479Q/MR479QA DENSO K16R-U, MR481QA/JL481Q

K7RF-11.

(2) Bend the outer side of electrode gently in order to obtain the necessary electrode clearance(0.8mm in normal case).

(3) Install the spark plug using a spark plug wrench with a torque of 18N.m.

7. Replacement of oil filter

Replace it per 40,000km (or 24 months) in normal case.

8. Check and replacement of compulsory ventilation valve PCV in crankshaft box

The PCV valve is installed to reduce the leakage of HC or other poisonous gases.

How to check the PCV valve:

(1) Blow air into the PCV valve from the cylinder cover side, and check whether it’s unblocked.

(2) Blow air into the PCV valve from the intake room side, and check whether it’s blocked.

If the PCV valve fails the above check, it shall be disqualified and replaced.

Note: Don’t take in air through the PCV valve because the petroleum substances inside are poisonous.

Check and replace it per 20,000km of driving (or 12 months) in normal case.

9. Check and replacement of all hoses and connections in engine

Check it per 40,000km of driving (or 24 months) in normal case, and replace it per 80,000km of driving (or 48 months).

After replacement, check it per 20,000km of driving (or 12 months).

25

When the engine is working, the cylinder block withstands high heat and mechanical load. In order to make the engine

work in normal and reliable operation, the cylinder block shall be of high strength, enough rigidity, compact structure, low

weight and easy servicing.

1. Gantry structure, plus well-deployed isolating plate and reinforced rib, provide high anti-bending and anti-twisting

strength.

2. It’s made of alloy casting iron, providing high strength and enough rigidity.

3. Cylinder block is short in length and light in weight. These engines are suitable to the transverse mounting, front installed

and front wheel driving.

4. The cylinder block is compact. The cylinder center distance is 87.5mm. There’s the main oil passage in the cylinder

block, connecting to the oil pump, oil filter, and oil pressure sensor directly. There’s optimized layout for cooling system of

water cavity and water flow. And the servicing is easy (Fig. 15).

Chapter 2 Cylinder Block Assembly

Section 1 Structural Characteristic of Cylinder Block

1

10

10

8

8

9

2

3

4

4

5

7

7

6

6

Fig. 15 Cylinder Block

1.Oil filter compo. 2.Six.flange bolt – grade B 3.RH installation bracket 4.Positioning bush

5.Oil passage screw plug 6.Dowel pin 7.Dowel pin 8. Dowel pin 9.Hang pin 10.Stud-end bolt

26

27

I. Grouped Servicing Data for Cylinder Block

Section 2 Detach, Assembly and Servicing of Cylinder Block

Color markBestGrouped dimension (mm)Name

φ78.7

φ78.7

φ78.7

φ81

φ81

φ81

φ78.655

φ78.655

φ78.655

φ80.955

φ80.955

φ80.955

φ52.025

φ52.025

φ52.025

φ48

φ48

φ48

1

2

3

1

2

3

1

2

3

1

2

3

1

2

3

0

1

2

MR479Q

MR479QA

MR481QA

JL481Q

MR479Q MR479QA (18mm

from bottom to up)

MR481QA JL481Q(16mm

from bottom to up)

Diameter of

cylinder bore

Piston skirt

diameter

Diameter of main bearing seat hole

Diameter of crankshaft main journal

Red

Yellow

Blue

Red

Yellow

Blue

Red

Yellow

Blue

Red

Yellow

Blue

Red

Yellow

Blue

Red

Yellow

Blue

√

√

√

√

√

√

+0.01
0

+0.01
0

+0.01
0

+0.01
0
+0.02
+0.01

+0.02
+0.01

+0.02
+0.01

+0.02
+0.01

+0.03
+0.02

+0.03
+0.02

+0.03
+0.02

+0.03
+0.02

+0.006
0
+0.012
+0.006
+0.018
+0.012

0

-0.006

-0.006

-0.012

-0.012

-0.018

28

(Note: data without engine type in table 4 are applicable to the general data of 4 engine types)

Color markBestGrouped dimension (mm)Name

2

2

2

2

2

φ43

φ43

φ43

φ51

φ51

φ51

φ40

φ40

φ40

φ48

φ48

φ48

1.486

1.486

1.486

1

2

3

4

5

1

2

3

1

2

3

1

2

3

1

2

3

1

2

3

MR479Q

MR479QA

MR481QA

JL481Q

MR479Q

MR479QA

MR481QA

JL481Q

Total central thickness of

crankshaft bearing

Diameter of

connection rod

big end

Diameter of

connecting rod

shaft

Central wall thickness of

connecting rod bearing shell

Red

Yellow

Blue

Orange

Green

Red

Yellow

Blue

Red

Yellow

Blue

Red

Yellow

Blue

Red

Yellow

Blue

Red

Yellow

Blue

√

√

√

√

√

√

√

√

•

+0.005
+0.002

+0.008
+0.005

+0.011
+0.008

+0.014
+0.011

+0.017
+0.014

+0.008
0

+0.016
+0.008

+0.024
+0.016

+0.006
0

+0.018
+0.012

-0.010

-0.015

-0.005

-0.010

0

-0.005

-0.012

-0.018

-0.006

-0.012

0

-0.006

+0.004
0

+0.008
+0.004

+0.012
+0.008

+0.012
+0.006

Before disassembling and checking the cylinder block of engine, remove the engine from the chassis. The power system

integrates the engine, the clutch and the gearbox as a whole. Therefore, detach the entire engine power assy., then take

off the gearbox and the clutch, and disassemble and check the cylinder block from the engine ASSY at last. The disassem-

bling procedures are briefly described as follows:

(I) Remove the Engine-power train (with Clutch and Gearbox)

1. Open the engine hood, and then remove the negative cables of from battery.

2. Drain the coolant in the radiator, and detach the radiator hoses and clamps.

3. Drain the refrigerator, and disassemble the air-conditioning pipe line.

4. Disassemble the pipe connecting the air filter assy.

5. Disassemble the clutch cable.

6. Detach the flexible cable of odometer.

7. Detach the throttle cable

8. Detach the vacuum booster hose.

9. Detach the water hoses of heat exchanger.

10. Detach the fuel deliver hose and the fuel return hose system.

11. Detach the engine wire harness.

12. Detach all kinds of control system hoses and connectors that connect the engine assy.

13. Lift the car to proper height with the automobile lifting equipment. Make sure the car to be locked and secured on lifting

equipment.

14. Drain the oil in the oil pan.

15. Drain the gear oil in the gearbox.

16. Detach off the front-left propeller and the front-right propeller.

17. Remove the exhaust pipe and muffler assy.

18. Remove the gear shift lever.

19. Intrude the engine lifting equipment below the car to hold the engine gently.

20. Detach the bolts on the front-left, rear-left and right mounted bracket racks of the engine and the vibration-isolating

spacers.

21. Check whether the connection between engine and carbody is completely detached, and disassemble the undetached

part.

22. Lower the engine gently with the engine lifting equipment, and take it out slowly from the cabinet.

23. Hoist the engine onto the rack of servicing power assy.

24. Remove the starter.

25. Remove the gearbox.

26. Remove the clutch.

27. Hoist the engine onto the rack for engine servicing.

(II) Detach the Cylinder Head Sub-assy. off the Engine Assy.

1. Drain the coolant out of the engine.

2. Remove the driving belt of AC generator and the water pump belt wheel (Fig. 16).

3. Remove the transmit belt of air-conditioner compressor.

4. Remove the air-conditioner compressor.

II. Preparations before Detaching and Checking the Cylinder Block

29

Fig. 16 Detach the AC Generator Belt

Fig. 18 Detach the Exhaust Manifold

Fig. 17 Detach the Generator Connectors and Wires

Fig. 20 Detach the No.2 Water Inlet Connecting flange

(1)

(2)

(4)

(3)

6. Remove the cylinder head cover.

connection(2), the oil pressure switch connector (3), and
the wire clip (4). Detach the wire harness, remove the
compulsory ventilation PCV hose of crankcase, remove
the 4 lock nuts and the seal pad, and remove the cylinder
head cover and the gasket (Fig. 17).

7. Remove the AC generator.

8. Remove the exhaust manifold (Fig.18).

9. Remove the phase sensor.

10. Remove the intake manifold.

11. Remove the oil dipstick and the guide (Fig.19).

12. Remove the No.2 water inlet flange and the gasket
(Fig.20).

13. Remove the No.3 and No.2 timing belt cover.

14. Set the No.1 cylinder at TDC of compression stroke.
(1)Turn the crankshaft pulley gently to align the “V”
groove with the timing mark “O” on the No.1 timing belt
cover (Fig. 21).

Fig. 19 Disassemble the Oil dipstick and guide tube

Fig. 21 Align with the Timing Mark on No.1 Timing Belt

30

Detach

the

generator connector (1),

the

wire

Fig. 25 Key Procedures of Detaching Camshaft Properly Fig. 26 Fix the Auxiliary Gear and Driving Gear with the Servicing Bolt

Fig. 23 Detach the Crankshaft Pulley

Fig. 24 Detach the Timing Pulley of Camshaft

Fig. 22 Make the Match Mark on the Timing

Belt and Camshaft Timing Pulley

Auxiliany

Driving gear

Serviang bolt

(2) Align the hole next to the mark “K” on the camshaft timing pulley with

the timing mark “U” at the front edge of exhaust cam bearing cap. If failing

to do so, turn the crankshaft a circle (360°) to align.

(3)After aligning with the timing mark as mentioned above, make the match

marks on the timing belt and the camshaft timing pulley, and draw the

clockwise arrow on the exterior side surface of timing belt (Fig. 22).

15. Detach the crankshaft pulley (Fig. 23).

16. Remove the No.1 timing belt cover and the timing belt, and don’t forget

to make the match marks on the pulley and the belt.

17. Remove the crankshaft timing pulley.

18. Remove the camshaft timing pulley (Fig. 24).

19. Detach the camshaft.

Note: The axial clearance of camshaft is quite small, so keep the camshaft horizontal during the detaching in order to

prevent the camshaft and the thrust bearing of cylinder head from being damaged.

(1) Turn the intake camshaft till the positioning hole on the auxiliary gear is at the upside(Fig. 25).

(2) Remove the two bolts and the No.1 bearing cap of intake camshaft.

(3) Fix the auxiliary gear of intake camshaft with the driving gear M6 screw hole by a M6x16 bolt, so as to eliminate the

torsion spring force of the auxiliary gear (Fig. 26).

install positioning hole

31

(4) Detach the bearing cap. In the sequences shown in the Fig., detach and remove the 8 intake camshaft bolts (Fig. 27).

After removing the cam bearing cap, if the camshaft can’t be lifted up vertically, re-fix it to the bearing cap with 2 bolts, lift

the camshaft gear, and loose and remove the bearing cap bolts alternately.

Don’t pry the camshaft by force with tools or other articles in order to prevent the components from being damaged (Fig.

28).

(5) Detach the exhaust camshaft. Note: Turn the positioning pin of exhaust camshaft to

where is slightly at the right side of the lower part, so that the cam peach-tips of No.1 and No.3 cylinders can push their

valve tappets respectively (Fig. 29).

a. Detach the No.1 bearing cover and oil seal of exhaust camshaft. If the No.1 bearing cap can’t be removed by hand,

leave it where it is with no bolt, and do not remove it by force (Fig. 30).

b. In the sequences shown in the figure, screw off and

remove the 8 bearing cap bolts by multiple and equal actions

(Fig. 31). After removing the cam bearing cap, if the

camshaft can’t be lifted up vertically, reinstall it to the No.3

bearing cap with 2 bolts, and loose and remove the 2 bearing

cap bolts alternately while lifting up the camshaft gear (Fig.

32). Don’t remove the camshaft by force in order to prevent

the components from being damaged.

Fig. 27 Sequences of Detaching the Bearing Cap Bolts of Intake Camshaft

Fig. 30 Don’t Detach the No.1 Bearing Cap of Exhaust Camshaft by Force

Fig. 28 Proper Way to Lift Up the Camshaft Vertically

Fig. 29 Location of Dowel Pin when Detaching

Exhaust Camshaft in Disassembly Dowel Pin

Fig. 31 Screw off the Bearing cap Bolts by Multiple

and Equal Actions from Sides to Center

Dower pin

32

20. Remove the sub-assy. of cylinder head

(1) In the sequences shown in the Fig., screw off and remove the 10 cylinder head bolts by multiple and equal actions (Fig.

33).

(2) Lift up the cylinder head off the dowel pin of cylinder block, and put it on the worktable. Be careful to protect the contact

surface between cylinder head and cylinder block, and pry inside the bulge between them with the screwdriver during the

course of disassembly (Fig. 34).

Fig. 34 Proper Way of Prying apart the

Cylinder Head from Cylinder Block Gently

Fig. 33 Sequences of Loosen off and

Detaching the Cylinder Head Bolts

Fig. 32 Proper Way of Lifting up the

Exhaust Camshaft Vertically

33

(I) Detach

1. Detach the 6 bolts and the flywheels (Fig. 35).

2. Detach the 2 bolts and the rear-end cover-plate (Fig. 36).

3. Detach the 2 bolts and the adjusting frame of AC generator (Fig. 37).

4. Detach the 3 bolts and the mounted bracket at the right side of engine (Fig. 38).

5. Remove 3 bolts and the water pump, and take off the O-

shaped ring.

6. Remove the oil filter.

7. Remove the oil pressure switch.

8. Remove the knock sensor.

9. Remove the oil sump pan and the oil pump.

10. Remove 6 bolts, and remove the rear oil seal retainer

and gasket (Fig. 39).

III. Disassembly, Examination and Servicing of Cylinder Block

Fig. 35 Detach the Flywheel Fig. 36 Detach the Rear-end Cover-plate of Cylinder Block

Fig. 37 Detach the Adjusting frame of AC Generator Fig.38 Detach the mounted brocket at the Right Side of Engine

Fig. 39 Detach the Rear Oil Seal Ring of Crankshaft

34

11. Check the axial clearance of connecting rod, move the
rod forward and backward, and measure the axial clearance
with the micrometer (Fig. 179).

12. Detach the connecting rod cap and check the oil film clear­ance (refer to Chapter 4 Section2).

13. Remove the piston and the connecting rod compo.

(1) Clear all the carbon deposit around the cylinder opening
with a reamer (Fig. 40).

(2) Put boot on the connecting rod bolt with the short hose in
order to protect the crankshaft from being damaged.

(3) Push the piston, connecting rod compo. and the upper
bearing shell out of the top of cylinder block. Put the connect­ing rod bearing, connecting rod and connecting rod cap
together. Locate the piston and connecting rod compo. in
proper sequence.

14. Check the axial clearance of crankshaft (refer to Chapter
5 Section2).

15. Detach the main bearing cap and check the oil film clear­ance.

16. Remove the crankshaft

(1) Lift and take out the crankshaft.

(2) Remove the main bearing upper half and the upper thrust
washer off the cylinder block. Locate the main bearing cap,
main bearing and thrust washer in proper sequence (Fig. 41).

(II) Check

1. Clean the cylinder block. Clear the residue of cylinder
gasket off the topside of cylinder block with the gasket
scraper. Clean completely the cylinder block with soft brush
and solvent (Fig. 42). Check whether there’re damages or
cracks on the topside of cylinder block or in the main bearing
seat, screw hole, oil passage and internal cavity.

2. Check the flatness of topside of cylinder block. Measure the
flatness of surface contacting the cylinder head gasket with
the precision ruler and the thickness feeler. The maximal warp
tolerance is 0.05mm. If the warp is bigger than the maximal
value, replace the cylinder block (Fig. 43). There has been no
deformation over-difference in the application of Geely
engines. If over-difference occurs, refine the flatness by grind­ing the topside of cylinder block. The cylinder compression
ratio may go up if the block top surface is over-ground.

3. Check whether there’s vertical scratch upon the cylinder. If
there’s deep scratch, the 4 cylinders shall be re-bored.
Replace the cylinder block if necessary (Fig. 44).

4. Check the inside diameter of cylinder. There’re 3 dimension groups, named as group “1”, “2” and “3” of standard diam­eter (Fig. 45). Print the group number upon the bottom of cylinder block.
Measure at position of A, B and C the diameters in the thrust direction and in the transverse axis direction with the cylinder
diameter gauge (Fig. 46).

Fig. 41 Locate the Main Bearing cap, the

Main Bearing and the Trust Washer

Fig. 40 Clear the Carbon Deposit around

the Cylinder Port with Reamer

Fig. 42 Clear the Residue of Gasket on

the Upper Surface of Cylinder Block

35

Fig. 43 Check the Straightness of Cylinder Block Top Plane

Fig. 44 Check the Vertical Scratch on Cylinder Wall

Abrasion characteristics of engine cylinder bore:

The abrasion condition reaches the most rigid point at 10mm away from the TDC, and improves gradually along with the

piston going downward. The maximal abrasion of cylinder wall happens when the 1st piston ring reaches the TDC.

The maximal radial abrasion of cylinder happens in the plain vertical to the crankshaft axis, and at the side near to the

intake valve. The oil film at this side of cylinder wall gets thinner by washing out; and in the meantime the entrance of dust

in air speeds up the abrasion of cylinder wall on the side of intake port. When the temperatures of cylinder walls at front

and rear ends of in-line engine are low, the abrasion is great.

Fig. 45 Three Groups of Standard Cylinder Inside

Diameters Printed on the Bottom of Cylinder BlockCylin-

der number: No.1, No.2, No.3 No.4, Dimension groups,

Number 1,2 or 3

Fig. 46 Measure the Cylinder Diameters in Directions of 1 and

2 at positions of A, B and C with the Cylinder Diameter Gauge

Cylinder number NO.1 NO.2 NO.3 NO.4

Dimension gronps

Number 1,2or3

forward

Forwrd

10mm

10mm

1 Trust direction

2 Transverse axis direction

36

Fig. 47Trim the Cylinder Opening Side with Reamer

Fig. 49 Detach the Piston Ring

Fig. 48 Check How the Piston Matches the Piston Pin

Fig. 50 Remove the connecting rod off the piston

(1) .Standard diameter, standard type of dimension groups refers

to table 4:

(2) .Maximal diameter, standard type: 78.93mm

(3) .Extra dimension 0.50 (type): 79.43mm

If the diameter is bigger than the maximal value, all the 4 cylinders

shall be re-bored. Replace the cylinder block if necessary.

5. Trim the bulge of cylinder upper part

Remove the bulge generated by abrasion and the combustion

residue around the cylinder opening. If the abrasion is smaller than

0.2mm, refine the cylinder opening side with a reamer (Fig. 47).

6. Check how the piston matches the piston pin, and try to move

the piston forward and backward. If the move occurs, replace the

whole set of piston and piston pin (Fig. 48).

7. Detach the piston ring (Fig. 49)

(1) Remove the 2 compression rings with the piston ring expander.

(2) Remove the oil ring and the liner ring by hand. The piston ring

must be located in proper sequence.

8. Remove the connecting rod off the piston, press the piston pin

out of the piston with the dedicated servicing tools, and take out the

connecting rod (Fig. 50). Do not deform the piston by pressing it.

Make sure the piston and the pin come from the same original kit.

Locate the piston, piston pin, the ring, the connecting rod and the

bearing shell in proper sequence.

9. Clean the piston, clear the carbon deposit with scraper, and

wash the piston completely with solvent and brush.

10. Check the clearance to decide the cylinder servicing dimen-

sions.

(1) Check the oil film clearance of piston

There’re 3 dimension groups, named as group “1”, “2” and “3” of standard piston diameter.

37

Fig. 54 Check the Opening Clearance of Piston Ring

Fig.51 Position to Measure the Cylinder Diameter

Fig. 52 Mount the Pistons with the Same Numbers

as the Group Marks on Cylinder Block top side

Fig. 53 How to Locate the Piston Ring When Checking

the Opening Clearance of Piston Ring

NO.1,2or3

NO.1,2or3

Front-end mark

(concave cavity)

97mm

a. Measure the piston diameter vertical to the central line of piston

pinhole at 18mm away from the piston bottom side with micrometer

(Fig. 51). The standard piston diameter refers to table 4.

Extra dimension 0.5 (type): 79.115 to 79.145mm

b. Measure the inside diameter of cylinder bore in the thrust direc-

tion (Fig. 46).

c. Calculate the oil film clearance between the cylinder and the

piston by subtracting the measured piston diameter from the

measured inside diameter of cylinder bore.

d. If the oil film clearance is greater than the maximal value, replace

all the 4 pistons, and re-bore the 4 cylinders.

e. Replace the cylinder block if necessary.

f. In the case of using the new cylinder block, make sure to use the

pistons that have the same number marks as the dimension group

marks printed on the cylinder block topside (Fig. 52). In this way to

match the servicing dimension specification, the oil film clearance

may comply with the standard: 0.075 to 0.095mm. It’s stipulated that

the maximal oil film clearance is 0.115mm.

(2) .Check the clearance of piston ring opening to obtain the servic-

ing data reference

a. Press the piston ring into the cylinder hole.

b. Use the piston as the tool, with the piston top downwards, to push

the piston ring to the bottom part that is 97mm away from the

cylinder block topside, just exceeding the ring distance (Fig. 53).

c. Measure the opening clearance with the thickness feler (Fig. 54).

Standard opening clearance:

Ring1: 0.20 to 0.40mm;

28.5mm

38

Ring2: 0.20 to 0.40mm;

Oil ring: 0.20 to 0.7mm.

Maximal opening clearance:

Ring1: 1.05mm;

Ring2: 1.20mm;

Oil ring: 1.10mm.

d. If the opening clearance is greater than the maximal value, replace the piston ring.

e. If the opening clearance is still greater than the maximal value after installing the new piston ring, re-bore the 4 cylinders

or replace the cylinder block.

11. Check the radial run-out of crankshaft

(1) Put the crankshaft upon the V-shaped block.

Fig. 56 Check and Measure the Main

Journal and the Connecting Rod Journal

of Crankshaft

Fig. 55 Check and Measure the

Radial Run-out of Crankshaft

(2) Measure the radial run-out of the central journal (Fig. 55). The

maximal standard of radial run-out is 0.03mm. If the measured radial

run-out is greater than the maximal value, replace the crankshaft.

12. Check the main journal and the connecting rod journal

(1) Measure diameter of each main journal and connecting rod

journal with micrometer (Fig. 56).

Diameter of main journal and connecting rod journal refers to table 4:

If the measured diameter fails the requirement, check the oil film

clearance, and grind or replace the crankshaft if necessary.

(2) Check the cylindricity of each main shaft journal and connecting

rod journal.

Maximal cylindricity: 0.02mm. If the measured cylindricity is greater

than the maximal value, replace the crankshaft. If necessary, grind

the main journal or the connecting rod journal till the diameter is

smaller than that of the finished product, and install the bearing shell

matching the new dimension in order to make sure the oil film clear-

ance is qualified.

(III) Bore and Grind the Cylinders

If the cylinder hole wears so much that the cylinder shall be bored, the

4 cylinders must be bored and ground, and equipped with the extra-

dimension pistons. Replace all the piston rings to match the extra-

dimension pistons. Take MR479Q for example:

1. Install the extra-dimension pistons

Diameter of extra-dimension pistons:

Extra-dimension 0.50 (type): 79.155 to 79.185mm.

2. Calculate the cylinder-boring quantity

(1) Measure the piston diameter vertical to the central line of piston

pin at 18mm away from the piston bottom side with micrometer (Fig.

51).

(2) Calculate the re-boring quantity for each cylinder according to the

formula below. The re-boring distance

39

(1) Preparation

1. Cleaning

Clean the to-be-assembled components completely, keep the worktable clean, and locate the compo. in proper order.

2. Lubrication

Before installing the components, paste the new engine oil onto all sliding and rotating surfaces.

3. Replacement

Replace all the O-shaped rings, oil seals and seal gaskets and damaged components.

4. Tools

Complete set of tools is available. The torque wrench shall pass the examination so as to fasten the bolt with the specified

torque.

(2) Reinstallation

1. Assemble the piston and the connecting rod

(1) Smear engine oil onto the piston pin and the piston pinhole;

(2) With the front-end marks on piston and connecting rod at the same side, push in the piston pin by thumb;

(3) Press in the piston pin with the dedicated servicing tools.

2. Mount the piston rings

IV. Reassembly

of cylinder = P+C-H. In the formula, P = piston diameter, C = piston oil film clearance as big as 0.075 to 0.095mm, and H

= grinding allowance as big as 0.02mm or smaller.

3. Bore and grind the cylinder to meet the calculated dimensions

Maximal grinding: 0.02mm. Over-grinding may damage the cylindricity of finished product.

Fig. 57 Difference between the Upper and

Lower Main Bearing Shell

Fig. 58 How to Mount the Main Bearing

onto the Cylinder Block

(1) Install the oil ring and the liner ring by hand;

(2) Install the 2 compression rings with the piston ring

expander, with the marks of “T” upwards;

(1) Locations of piston rings: Put the piston rings with

their openings 90° from the connections alternately to

ensure good sealing effect.

3. Mount the connecting rod bearing shell

(1) Align the protrusion of bearing with the recess on

the connecting rod or the connecting rod cap;

(2) Mount the bearing into the connecting rod and the

connecting rod cap.

4. Mount the main bearing

The upper main bearing half has oil-inlet groove and oil

hole, which is not designed for the lower one. Do not

reverse their positions when assemble (Fig. 57).

(1) Align the protrude of upper main bearing with the

recess on the cylinder block seat, and push in the 5

upper main bearing (Fig. 58). Don’t smear oil onto the

main bearing seat hole and the main bearing half

backside..

40

(2) Align the protrusion of lower main bearing with the recess on the main bearing cap, and push in the 5 lower main

bearings (Fig. 59). Don’t smear oil onto the main bearing seat and the main bearing half backside.

5. Mount the upper thrust washer

Mount 2 thrust washer at both sides of No.3 main bearing of cylinder block, with the oil groove outwards. Don’t mount

oppositely or drop them (Fig. 60).

6. Put the crankshaft upon the cylinder block

Smear the engine oil onto the operating surface of main bearing shell and thrust washer. Smear the engine oil onto the

main journal of crankshaft, and insert the crankshaft into the bearing hole of cylinder block gently.

7. Mount the main bearing cap and the lower thrust washers

(1) Mount the 2 thrust washers onto the No.3 main bearing cap, with the oil duct outwards (Fig. 61).

Mount the 5 bearing cap onto proper locations, with the arrow marks forwards. Assemble them according to the shown

arrows and sequences (Fig. 62).

(2) Mount and screw on the 10 main bearing cap bolts (with a thin layer of engine oil applied on the bolt screw) according

to the shown sequence (Fig. 63) by multiple and equal actions, the MR479Q/MR479QA torque is 60N.m, the MR481QA

torque is 70N.m, the JL481Q torque is 80N.m.

8. Check the axial clearance of crankshaft

The crankshaft shall be able to rotate freely. Check and measure the axle clearance with the plastic oil clearance gauge

(Fig. 64)

Fig.61 Mount the Thrust Washers onto the Main Bearing Cap Fig.62 Location to Install the Main Bearing Cap

Front end of engine

Fig. 59 How to Mount the Main Bearing onto

the Main Bearing Cap

Fig. 60 How to Mount the Thrust Washer onto

the Cylinder Block

41

b. Mount and screw on the locking nuts by multiple and alternate actions, with the torque of 29N.m(1st screwing) (Fig.

67). If the locking nuts can’t stand the required torque, replace the whole set of connecting rod bolts and locking nuts.

9. Install the piston and the connecting rod components

(1) Suit the connecting rod bolt with short hose in order to protect the

crankshaft from being damaged.

(2) Push the pistons and connecting rod compo. that match the

cylinders in their numbers into the cylinders with the piston ring

compressor, with the front-end marks of piston forwards. The oil ring

gap and their liner ring gap shall be 180° apart (Fig. 65).

10. Mount the connecting rod caps

(1) Install the connecting rod caps onto the connecting rods

a. Match the connecting rod caps with the proper connecting rods

according to the numbers.

b. Install the connecting rod caps, with the front-end marks forwards

(Fig. 66).

Fig. 63 Sequence to Screw on the Main Bearing Cap

Fig. 64 Check the Axial Clearance of Crankshaft with the

plastic oil clearance gauge

Fig. 66 Have the Marks of Connecting Rod and Connecting Rod

Cap Forwards to the Engine Front End During Mounting Process

Fig. 65 Locations of the Oil Rings and the compres-

sion Rings Relative to the cylinder block

Code mark T of NO.2 compressior ring

Front - End Mark
(Protrude)

(2) Mount the nuts of connecting rod caps

Screw on the nuts of connecting rod caps gradually in 2 steps. Replace the bolts of connecting rod cap if any crack or

deformation is found.

a. Smear a thin layer of engine oil onto the lower part of nuts of connecting rod caps;

42

c. Tighten the locking nut to 65+2.5 N.m;

d. MR481QA/JL481Q connecting rod bolts screwing torque;

1) Screwing 30N.m,2st screwing 70±2N.m

f. Check whether the crankshaft rotates freely.

11. Check the axial clearance of connecting rod (Fig. 180)

The standard axial clearance is 0.15 to 0.30mm, and the

maximal axle clearance is 0.35mm.

12. Mount the rear oil seal ring

Mount the new gasket and the oil seal ring with 6 bolts, with the

torque of 9.3N.m.

13. Mount the oil pump and the oil sump

14. Mount the knock sensor Mount the knock sensor (Fig. 68)

with dedicated servicing tools, with the fastening torque of

20N.m.

15. Mount the oil pressure switch

a. Smear the adhesive agent onto the 2nd or the 3rd screws

thread of oil pressure switch;

b. Mount the oil pressure switch with the dedicated servicing

tools.

16. Mount the oil filter

17. Mount the water pump

(1) Put the new O-ring onto the cylinder block.

(2) Mount the water pump with 3 bolts, with the fastening

torque of 14N.m (Fig. 69).

18. Install the mounted bracket at the right side of engine Mount

the installation rack at the right side of engine with 3 bolts, with

the torque of 51N.m.

19. Assemble the adjusting frame of AC generator

Assemble the adjusting frame of AC generator with 2 bolts, with

the torque of 31N.m.

20. Install the cylinder head (refer to Chapter3)

21. Mount the timing belt and the pulley

22. Mount the rear-end cover-plate of cylinder block

Mount the rear-end cover-plate with 2 bolts, with the torque of

5.6N.m.

23. Assemble the flywheel

a. Align the position hole of flywheel with the position hole pin

at the rear end of crankshaft;

Fig. 68 Install the Knock Sensor

Fig. 69 Install the Water Pump

Fig. 67 Requirements of Fastening the Locking Nuts

of Connecting Rod Cap

43

b. Fasten the bolt by multiple and equal actions in the shown

sequence (Fig. 70), with the torque of 78N.m.

c. Check whether the clearance between the lower end of

speed sensor and the tooth top of flywheel signal disc is

1±0.10mm with a bolt-fastening sensor with the torque of

8N.m.(Complete when mounting the power assembly)

Fig. 70 Sequence to Fasten the Flywheel Nuts

44

W

hen the engine works, cylinder head bears relatively high thermal load and mechanical load. In order to ensure supe-

rior combustion and reliable work, cylinder head must optimize combustion chamber, intake duct, exhaust duct and cooling

water chamber should be arranged rationally. It should have relatively high heat transmissibility, sufficient strength and

rigidity, in addition, it should also feature light weight and compact structure.

Structural characteristics of cylinder head:

1. Adopts cast aluminum alloy: 439mm long, 116mm high and 10kg in weight.

2. Combustion chamber is pent-roof shape. Spark plug is in the middle part.

3. The angle between intake valve and exhaust valve is 22º, angle of intake duct to horizontal plane is 38º-40º and exhaust

duct is arranged horizontally. Intake duct has smooth wall and small resistance. Admission tends to form rotational flow. It

also features good exhaust and purge effect.

4. The structure is relatively complicated; there are four combustion chambers, 16 valves, double camshaft, ten bearing

holes, 16 tappet holes, water chambers with different shapes, jet holes, oil passage, gear chamber, eight intake/exhaust

ducts, many bolt holes, a lot of spacer plates and reinforced ribs. Valve stem guide and valve seat that are made of alloy

cast iron and refractory steel are pressed into cylinder head by means of shrinking (Fig. 71).

Chapter 3 Cylinder Head Assembly

Section 1 Structural Characteristics of Cylinder Head

1. In the process of removing sub-assy. of cylinder head, use special repair tools in the sequence shown in Fig. 33, loosen

and remove cylinder head bolts in several equal operations. Incorrect sequence of bolts removing might cause warping or

breaking of cylinder head. At the same time, prevent distortion and damage of fasteners caused by removal of cylinder

I. Detach

Section 2 Detach, Assembly and Repair of Cylinder Head

Fig. 71 Cylinder head view

45

1. Clean piston-top surface and cylinder block

(1) Rotate the crankshaft, enable each piston to rise to the TDC, check carbon deposit on piston top-surface, whether

residue gasket material on surface of cylinder block has been cleaned up.

(2) When using compressed air to purge carbon deposit and engine oil in bolt hole, be careful enough so as not to harm

your eyes when using high pressure air.

2. Clean cylinder head

(1) Remove gasket material

Use gasket scraper to eliminate all residual gasket material on contact surface of cylinder head. Pay attention not to scrape

contact surface of cylinder head (Fig. 75).

(2) Clean combustion chamber

Use wire brush to remove all carbon deposits in combustion chamber (Fig. 76). Pay attention not to scrape lower contact

surface of cylinder head and cylinder block.

II. Inspection

Fig. 72 Remove Valve Tappet

Fig.73 Use long nose pliers to remove oil seal

Fig. 74 Use compressed air and magnet bar to

remove valve spring seat

head when engine is warmed up, that is to say, detach it when

the engine is in cold state.

2. Remove valve tappet

When removing valve tappet (Fig. 72), use a marker to write

down sequence number, arrange valve tappet according to the

sequence.

3. Remove valve

(1) Use special repair tool to compress valve spring and remove

two keepers.

(2) Remove spring retainer, valve spring and valve. Place all

removed components according to sequence.

(3) Use long nose pliers to take out oil seal (Fig. 73).

(4) Use compressed air and magnet bar, puff and take off valve

spring seat (Fig. 74).

46

(3) Clean valve guide

Use valve guide brush and solvent to clean all valve guides (Fig. 77).

(4) Clean cylinder head

Use soft brush and solvent to clean cylinder head thoroughly (Fig. 78).

3. Check cylinder head

(1) Check planeness

Use precision ruler and feeler gauge to measure whether there is any warping on contact surfaces of cylinder head (Fig.

79). Specified max. allowable warping value of planeness: At cylinder block side: 0.030mm, manifold side: 0.08mm If

planeness exceeds the above-mentioned maximum value, replace the cylinder head.

(2) Check whether there is any crack Use dye penetrant to check (Fig. 80) whether there is crack in combustion chamber,

air inlet, air outlet and the surface of cylinder head. Replace cylinder head if any crack is found.

4. Clean valve

(1) Use scraper to eliminate carbon deposit attached on valve end.

(2) Use wire brush to eliminate fuel combustion residue on the valve thoroughly (Fig. 81).

Fig. 77 Clean valve guide Fig. 78 Clean cylinder head

Fig. 75 Don’t scrape surface when eliminating

residual material on contact surface of cylinder head

Fig. 76 Use wire brush to remove carbon

deposit in combustion chamber

47

5. Check valve stem and valve guide

(1) Use inner dia. micrometer to measure inner diameter of

guide (Fig. 82).

Inner diameter of valve guide: 6.000-6.018mm;

(2) Use micrometer to measure diameter of valve stem(Fig. 83).

Diameter of valve stem:

Intake: 5.960-5.975mm;

Exhaust: 5.960-5.975mm.

(1) Standard oil clearance

Subtract measured valve stem diameter from measured

inner diameter of the valve guide to obtain:

Intake: 0.025-0.058mm;

Exhaust: 0.025-0.058mm.

(2) Max. oil clearance

Intake: 0.08mm

Exhaust: 0.10mm

If oil clearance is larger than the maximum value, replace valve

and valve guide.

Fig. 79 Check planeness on three planes of cylinder head

At cylinder block side

At intake manifold side

At exhaust manifold side

Fig. 80 Use dye penetrant to check

whether there is crack in cylinder head

Fig. 83 Measure diameter of valve stem at

position shown in the Fig.

Fig. 82 Check and measure inner diameter of valve guide

Fig. 81 Eliminate fuel combustion residue on valve

48

6. Check and grind valve 89º sealed cone

(1) Grind valve to eliminate pockmark and carbon deposit. Apply a thin layer of valve abrasive paste on the valve seat,

then use a handle with a rubber sucker on one end to suck the valve plane tightly. Grasp handle to move upwards and

downwards manually and turn the valve, grinding and

tapping seat surface. Turn valve slowly while tapping

(2) seat surface repeatedly to make continuous thin

belt.Check and grind valve to correct valve cone angle

(Fig.84),valve cone angle: 45.5 º±15’.

(3) Check edge thickness of valve head (Fig. 85), standard

edge thickness is 0.8-1.2mm. Allowable min. edge

thickness is 0.5mm. If edge thickness is less than the

minimum value, replace the valve.

(4) Check full length of valve (Fig. 86)

Maximum full length:

Intake: 87.60mm

Exhaust: 87.95mm

Minimum full length:

Intake: 86.40mm

Exhaust: 87.65mm.

If full length is less than the minimum value, replace the

valve length.

(5) Check abrasion on the end surface of valve stem and

trim it. If the end of valve stem is abraded, use abrasive

wheel to grind and trim the end or replace valve. Be noted

not to exceed minimum valve (Fig. 87).

7. Check valve seat

(1) Use 45ºcarbide ceramic reamer to ream valve seat, cut away some metal to clean up the valve seat (Fig. 88).

(2) Check valve seating

Firstly apply a layer of red lead oil on the contact surface of valve. Do not turn the valve when installing it. Let it fall down

Fig. 86 Check full length of valve

Fig.87 Grind valve end

Edge thickness

Full length

Fig. 84 Grind valve

Fig. 85 Check thickness of valve edge

49

by its own weight, press valve slightly to connect with valve

seat.

(1) Check fitting quality of valve contact surface and valve

seat:

a. If red lead oil on valve contact surface is distributed in

360º encircling valve center, it indicates that the valve is

coaxial with the surface, otherwise replace the valve.

b. If red lead oil on valve seat is distributed in 360º encircling

valve seat center, it indicates that the guide is coaxial with

the surface, otherwise replace the valve.

c. Check the width and position of valve sealing tape. The

width of valve sealing tape with 45º seat surface should be

1.0-1.4mm. Be noted to control another two cone angles,

making 45º seat surface to be in the middle of surface, a

criterion for qualification (Fig. 89)

(2) If the above requirements cannot be met, correct valve

seat using the following method:

a.If 1.0-1.4mm valve sealing belt on 45º seat surface is a bit

high, use 30º and 45º reamer to shape the valve seat (Fig.

90).(Note: assure valve stem valve seat. Please assure that

the trueness of valve seat and valve stem is 0.030mm.

b. If 1.0-1.4mm valve sealing belt on 45º seat surface is a bit

low, use 60º and 45º reamer to shape the valve seat (Fig.

91).

(3) Grind seat surface after reaming

Manually grind valve and valve retainer seat. Apply a thin

layer of valve abrasive paste on valve seat surface, then use

a rubber sucker with wooden handle to suck valve end

surface, tap valve 45º seat surface while turning the valve,

so as to grind continuous belt with width of 1.4mm (Fig. 92).

Fig. 88 Clean up valve seat

Fig. 89 Check fitting condition on contact surface

Fig. 90 High fitting mark of valve sealing belt

Fig. 92 Grind valve and valve seat manuallyFig. 91 Low fitting mark of valve sealing belt

45ºcarbide ceramic reamer

width

50

(4) Clean cylinder head, clean valve

Use kerosene and soft brush to clean cylinder head and valve

thoroughly.

8. Check valve spring

(1) Use steel L square to measure verticality of valve spring. Allow-

able maximum deviation angle: 2º(Fig. 93). If deviation value exceeds

the maximum value, replace the valve spring.

(2) Use vernier caliper to measure free length of valve spring (Fig.

94). Free length: 39±0.3mm; if free length does not meet requirement,

replace valve spring.

(3) Use spring tester to measure pulling force of valve spring at speci-

fied installation length (Fig. 95). Installation pulling force when the

length of spring is 31.7mm: 160±8N. If installation pulling force does

not meet requirement, replace valve spring.

9. Check camshaft and bearing

(1) Check radial run out of camshaft.

a. Place the camshaft on a V block;

b. Use a dial gauge to measure circumferential radial runout at middle journal (Fig. 96);

specified maximum circumferential radial run out: 0.03mm(). If circumferential radial run out: is larger than the maximum

value, replace the camshaft.

(2) Check cam peach-tip

Use micrometer to measure the height of cam peach-tip (Fig. 97).

Fig. 94 Check and measure free length of spring

Fig. 95 Check and measure elasticity of spring

Fig. 96 Check and measure radial run out of camshaft Fig. 97 Measure cam peach-tip height

Fig. 93 Check and measure verticality of spring

Deviation

51

b) Put the camshaft on cylinder head;

c) Place a plastic clearance gauge on each camshaft

journal (Fig. 101).

d) Install bearing cap;

Torque: 13N.m, pay attention not to rotate the camshaft.

e) Remove bearing cap, use plastic clearance gauge to

measure the clearance:

Standard oil clearance: 0.035-0.072mm;

Maximum oil clearance: 0.10mm

If the oil clearance is larger than the maximum value,

replace camshaft, replace the entire bearing cap and

cylinder head if necessary.

Standard height of cam peach-tip refers to Table 1.

If the height of peach pit does not meet requirement, replace the

camshaft.

(3) Check camshaft diameter

Use micrometer to measure journal diameter (Fig. 98).

Journal diameter:

NO.1 Exhaust: 24.949-24.965mm

Other: 22.949-22.965mm

If journal diameter does not meet requirement, check oil clearance.

(4) Check camshaft bearing

Check whether the bearing has shellingout and ablation; if the

bearing is damaged, replace the entire set of bearing cap and

cylinder head (Fig. 99).

Fig. 100 Check free distance of camshaft gear spring

Fig. 101 Check oil clearance on camshaft

Free distance

Fig. 98 Measure journal diameter of camshaft

Fig. 99 Check damage of camshaft bearing

(5) Check camshaft gear spring

Use vernier caliper to measure free distance at both ends of spring (Fig. 100).

Free distance: 17.02-17.10mm. If free distance does not meet stipulation, replace gear spring.

(6) Check oil clearance on camshaft journal

a) Clean bearing cap and camshaft;

Plastic clearance gauge

52

7 Check axial clearance of camshaft (Fig. 102);

a) Assemble the camshaft;

b) Use dial gauge to measure axial clearance while moving the

camshaft forwards and backwards;

Standard axial clearance:

Intake: 0.030-0.085mm;

Exhaust: 0.035-0.090mm;

Maximum axial clearance: 0.11mm.

If axial clearance is larger than the maximum value, replace

camshaft, replace the entire set of bearing cap and cylinder head

if necessary.

8 Check backlash of the camshaft gear

a) Mount the camshaft, but without the exhaust cam

auxiliary gear.

b) Use dial gauge to measure backlash (Fig. 103):

Standard backlash: 0.020-0.200mm;

Maximum backlash: 0.30mm.

If the backlash exceeds maximum value, replace the camshaft.

10. Check valve tappet and tappet pore diameter

(1) Use inside micrometer to measure tappet pore diameter of

cylinder head (Fig. 104).

Tappet pore diameter: 31.000-31.025mm.

(2) Use micrometer to measure tappet diameter (Fig.

105). Tappet diameter: 30.966-30.976mm

(3) Calculate oil clearance

Subtract measured tappet diameter from measured tappet pore

diameter.

Standard oil clearance: 0.015-0.055mm

Maximum oil clearance: 0.07mm.

If oil clearance is larger than the maximum value, replace tappet.

Replace cylinder head if necessary.

11. Check planeness of junction surface of intake
manifold and exhaust manifold. Use precision
ruler and feeler gauge to measure planeness of
the surface contacting with cylinder head (Fig.

106).

Planeness of intake manifold plane: 0.080mm.

Planeness of exhaust manifold plane: 0.080mm.

Fig. 102 Check axial clearance of camshaft

Fig. 103 Use dial gauge to measure backlash

Fig. 104 Check and measure valve tappet pore diameter

Fig. 105 Check and measure the diameter of valve tappet

12. Check cylinder head bolt

When outer diameter is less than the minimum value, replace

cylinder head bolt (Fig. 107):

Standard outer diameter: ?8.575 ± 0.03mm.

Minimum outer diameter: ?8.47mm.

53

Fig. 107 Measure the outer diameter of cylinder head bolt

III. Replacement of Valve Guide

Fig. 106 Check planeness of junction surface of

intake and exhaust manifold

Fig. 109 After cylinder head is heated, use

special servicing tool to knock valve guide out

Fig. 110 Use inside micrometer to measure pore

diameter of valve guide on cylinder head

Intake

Exhaust

Fig. 108 Heat cylinder head to remove valve guide

Max. oil clearance of intake valve: 0.058mm.

Max. oil clearance of exhaust valve: 0.058mm.

If the clearance is larger than the above maximum value,

replace valve and valve guide. Operating procedure is:

1. Heat cylinder head gradually to 80-100

o

C (Fig. 108).

2. Use special servicing tool and hammer to slightly knock the

valve guide out (Fig. 109).

3. Use inside micrometer to measure pore diameter of guide

installed on cylinder head (Fig. 110)

Pore diameter of standard valve guide (cold state): 11.000-

11.018mm.

4. Select new valve guide of( standard value or 0.05mm

larger).If pore diameter of guide installed on cylinder head is

larger than 11.018mm, machine this pore to the following dimen-

sion: 11.050mm.

54

Select new valve guide with outer diameter 0.05mm larger correspondingly. If this pore diameter on cylinder head is larger

than 11.050mm, replace the cylinder head.

5. Heat the cylinder head gradually to 80-100

o

C. Use special servicing tool and hammer to slightly knock new valve guide

in. The length extending out of the cylinder head is 12.5mm (Fig. 111).

6. Use a sharp 6mm reamer to ream the guide hole (Fig. 112), and ream the guide to the following dimension: 6.000-

6.018.mm

Dimension of valve stem is:

Intake: 5.960-5.975mm;

Exhaust: 5.960-5.975mm.

Guarantee standard oil clearance:

1. Bend the strap on ventilation baffle upwards, which prevents oil seal from sliding out.

2. Use screwdriver to pry out oil seal (Fig. 113).

3. Use special servicing tool and hammer to press in new oil seal (Fig. 114).

4. Apply a thin layer of all-purpose grease onto the edge of oil seal.

5. Restore strap on ventilation baffle to its original position.

IV. Replacement of oil seal on spark plug guide

Fig. 111 Method for knocking in new valve guide Fig. 112 Use 6mm reamer to ream valve guide pore

Adhesive tape

Fig. 113 Pry out oil seal of spark plug guide Fig. 114 Use repair tool to press new oil seal into spark plug guide

Sharp 6mm reamer

12.5mm

55

(1) Preparation

1. Cleaning

Completely wash all parts to be mounted. Keep work bench clean and make sure parts are

placed in order.

2. Lubricating

Before installing, smear engine oil onto all sliding and rotating surfaces.

3. Replacement

Replace all O-rings, oil seals, sealing gaskets and any other damaged parts

4. Tools

A complete set of tools is available. Wrenches shall be

calibrated, fasten the bolts with specified torque.

(2) Re-assemble

1. Re-assemble the guide of spark plug

When using new cylinder head, new guide for spark plug shall

be mounted.

(1) Mounting mark of spark plug shall be made on the guide of

spark plug. (Fig. 115)

Standard extrusion: 46.8-47.6mm

(2) Smear adhesive into the installation hole of spark plug guide

on the cylinder head. (Fig. 116)

(3) Use the standard pressing machine to press the guide of spark plug until standard protrusion

distance of 46.8-47.6mm has been reached. (Fig. 117)

V. Installation of cylinder head

2. Mount the air valve

(1) Use specialized maintenance tool to press the new oil seal in. Oil seal of intake valve is gray and wrapped with rubber,

while oil seal of exhaust valve is black and wrapped with metal. Do not confuse the two (Fig. 118, 119).

(2) Install the following parts: (Fig. 120):

a. valve b. spring seat c. valve spring d. spring retainer

(3) Use specialized servicing tool to press valve spring. Mount two keeper between valve stem and spring seat ring, until

they are completely locked. (Fig. 121)

Fig. 115 Marks on the spark plug guide

Fig. 117 Press in spark plug guide with pressing machineFig. 116 Apply adhesive to the spark plug guide install hole

Protrusion

Mark

Adhesive

Protrusion

56

(4) Use hammer of plastic veneer to strike the top end of valve stem to ensure good assembly .(Fig.122)

3. Mount valve stem and adjusting shim

Mount the valve stem and adjusting shim in line with the sequence numbers made before they are dismantled. Check by

hand whether the valve stem can rotate freely.

4. Install the cylinder head

(1) Place the cylinder head onto the cylinder block.

a. Place the new cylinder head gasket onto the cylinder block in a correct direction of installation. (Fig. 123)

b. Place the cylinder head onto the cylinder head gasket. Make sure they are precisely matched.

Fig.118 Press in valve new oil seal with servicing tools

Fig. 120 Assemble valve and spring compo

Fig. 119 Difference between oil seal of intake and exhaust Valve

Inlet

Grey surface

Black surface

Exhaust

Fig. 121 Method of install valve and spring compo

Fig. 122 Keypoint to mounting valve Fig. 123 Installing cylinder head gasket

(1)

(2)

(3)

(4)

57

(2) Tighten the bolts on the cylinder head

Not to use bolts with cracks or deformation, and strictly

follow the instruction on tightening. Cylinder head shall

be tightened with bolts in three steps.

a. Smear a thin layer of engine oil onto the below-head

part and thread of cylinder head bolts.

b. Tighten the ten bolts of cylinder head in several equal

operations in the shown sequence with a specialized

tool. (Fig. 124)

Two bolts with different lengths are available.

Use 90mm long bolt on the side of intake manifold (B).

Use 108mm long bolt on the side of exhaust manifold

(A).Tighten the bolts according to shown sequence in

(Fig.125) with several equal operations, with the torque

of 29N.m.

If bolt size does not meet specification, it shall be

replaced.

c. according to shown sequence in Fig. Tighten the bolts

on the cylinder head again.The torque is 95 3N.m

5. Mount the intake camshaft

(1) Fix the hex. head of camshaft onto the bench clamp.

Be noted not to damage camshaft.

(2) Mount circlip for camshaft gear (1), auxiliary gear for

camshaft(2), wave washer(3)(Fig.126). Note that pin on

the gear shall match with the end of gear circlip.

(3) Mount the ring clip (Fig. 127)

Fig. 125 Keys point to fastening cylinder head bolt

Fig. 127 Assemble clip rings on the intake camshaftFig. 126 Attentions on assemble Intake camshaft

Length

(A, B)

Fig. 124 Sequence of fastening cylinder head

bolt and installing position

+

-

58

Fig. 128 Matching of auxiliary gear and driving gear

Fig. 129 Correct position for installing exhaust

Fig. 131 Installing sequence of bearing cap

Fig. 130 Applying sealant

Auxiliary gear

Rotating

Driving gear

For assembly and servicing

Pin

Timing Mark

Dowel pin

Applying sealant

(4) Rotate the auxiliary gear of camshaft clockwise using

specialized servicing tool, so that holes of camshaft driving gear

and auxiliary gear can match. Mount the bolt for servicing (Fig.

128).

6. Mount air inlet/exhaust camshafts

As axial clearance of camshaft is very small, it’s important to

keep it horizontal when mounting. If camshaft fails to stay

horizontal, the parts pf cylinder head that bear axial thrust will

develop cracks, deformation and damage, thus making

camshaft to be stuck or break.

To avoid such problem, the following steps shall be taken:

(1) Mount camshaft on the exhaust side

a. Smear multi-purpose lubricating grease on the thrust

positions of camshaft.

b. Position the exhaust camshaft to make the dowel pin in an

angle counter clockwise from the axle of camshaft. In this

position, the peach tip of #1 and #3 cylinder cam can push the

valve tappet in a balanced way (Fig. 129).

c. Remove all the old filling material remaining on the surface.

d. Smear new filling material onto the exhaust camshaft bearing

cap (Fig. 130).

e. Mount the five bearing caps onto their corresponding

positions according to their sequence numbers and the arrow

direction (Fig. 131).

f. Smear a thin layer of engine oil onto the thread beneath the

bolt head of bearing cap.

g. Tighten these 10 bolts according to the sequence shown in

Fig. 132 in several equal operations with torque of 13N.m.

h. Smear the multi-purpose lubricating grease onto the edge of

new oil seal.

i. Knock the oil seal into position with specialized servicing tool.

Make sure that its edges are positioned correctly and push the

oil seal down to the bottom of the cylinder cap. (Fig. 133)

Aligning with

assembly

and servicing hole

Aligning with

mounting mark

59

Fig. 133 Installing camshaft seal

Fig. 132 Fastening bearing cap bolt

Fig.135 Matching marksFig. 134 Fix the position of dowel pin of exhaust camshaft

Fig. 137 Tighten bearing cap boltFig. 136 Assemble bearing cap

(2) Mount the intake camshaft on the air inlet side

a. Place the exhaust camshaft in a position so that dowel pin rotates to a level that is slightly higher than the top surface of

cylinder head (Fig. 134).

b. Smear multi-purpose lubricating grease onto thrust position of intake camshaft.

c. Engage the gears of intake camshaft with the gears of exhaust camshaft following the mounting mark on each gear.

Make sure not to confuse mounting mark with timing mark. (Fig. 135)

d. When gears mesh with each other, place intake camshaft onto the bottom hole of bearing seat.

e. Install the four bearing caps onto their corresponding positions in arrow direction and sequence numbers (Fig. 136).

f. Smear a thin layer of engine oil onto the thread below the bolt head of bearing cap.

g. Tighten eight bearing cap bolts in several equal operations, with torque of 13 N.m. (Fig. 137)

Dowel pin

Timing mark

Mounting mark

Mounting
mark

60

h. Detach the servicing bolts.

i. Mount the bearing cap of #1 camshaft in arrow direction. If the bearing cap of #1 camshaft is not in correct matching

position, use an screw driver to pry the cylinder head from the camshaft gear, and push the camshaft gear backward (Fig.

138).

j. Smear a thin layer of engine oil onto thread of two bolts low part. Tighten the two bolts with several alternate operations,

with torque of 13 N.m (Fig. 138).

k. Rotate the exhaust camshaft in clockwise direction. Fix the camshaft when dowel pin is placed upward.(Fig. 139)

l. Check whether the timing marks of camshaft gears match. When timing marks match, two mounting marks are on the

top, as shown in Fig. 140.

7. Inspect and adjust the clearance of valves.

Rotate the camshaft to position the camshaft tip upward. Inspect and adjust the valve clearance.

Valve clearance (under cool condition)

Intake valve: 0.15-0.25 mm

Exhaust valve: 0.25-0.35mm

8. Mount timing pulley of camshaft

(1) Make sure that dowel pins of camshaft align with the dowel pin slot on the side marked with “K” on the pulley before

the mounting process begins. If there are two dowel pin slots, only the one below the “K” mark will be used.(Fig.141)

Fig. 138 Mount No. 1 bearing cover Fig. 139 Check the position of dowel pin

Fig. 140 Check positioning mark Fig.141 Install camshaft pulley

Dowel pin

Mounting mark

Timing mark

61

(2) After the bolt of pulley has been fixed, fix the hex. head of camshaft to fasten the bolt of timing pulley with torque of 59

N. m

9. Install the frame of AC generator

Install the frame of AC generator with three bolts with torque of 31N.m.

10. Mount the timing pulley

Inspect whether matching mark on the timing belt match the mark on the end of #1 belt cover. If not, move the wheel until

they are matched. Align the mark on the timing belt with the mark on the timing pulley. (Fig. 142, 143)

Before mounting, wipe clean all oil and water on the surface of camshaft timing pulley and keep a clean surface. After

mounting, inspect whether the tension force between crankshaft timing pulley and camshaft timing pulley is normal.

11. Inspect valve timing

(1) Loosen the belt tensioner bolt (Fig. 144).

(2) Rotate the crankshaft for two cycles, starting from the TDC of cylinder I and returning to the TDC after two circles. Be

noted to rotate clockwise.

(3) Inspect whether each pulley aligns with the timing mark in Fig. 145. If not, re-install them.

(4) Tighten the belt tensioner bolt with torque of 37N.m.

(5) Put on rubber seal ring onto #1 timing belt cover.

Fig. 142 Check the matching mark on the timing belt

Fig. 144 Check the tension force of timing pulley Fig. 145 Adjust valve timing

Fig. 143 Align the matching mark on the

timing belt and camshaft timing pulley

62

12. Inspect the belt deflection

Requirement: Under a force of 20N, belt deflection shall be 5-6mm (Fig. 146).

If deflection fails to meet the above requirement, the belt tensioned shall be re-adjusted. (Fig. 147)

13. Use six bolts to fix #2 and #3 timing belt cover (Fig. 148) with torque of 7.4 N.m.

14. Mount the semi-circle plug

(1) Remove all old filling

(2) Fill new sealant onto the semi-circle plug (Fig. 149)

(3) Install the semi-circle plug onto the cylinder head

15. Mount cylinder headcover

(1) Remove all old seal material

(2) Fill the seal material onto cylinder head as shown in Fig. 150.

(3) Mount the gasket inside the lower liner ring slot of cylinder head.

(4) Mount the cylinder head with four seal gaskets and locking nuts, with a torque of 10.8 N.m.

16. Mount spark plug

17. Mount #2 water inlet connection flange

(1) Put a new gasket onto the cylinder head, with protruding end upward. (Fig. 151)

Fig. 148 Install No.2 and No.3 timing belt cover Fig. 149 Smear sealant to the semi-circle plug of cylinder head

Fig. 146 Check belt deflection

5 - 6mm

20N

Fig.147 Check timing belt deflection

Sealant

63

(2) Connect water inlet hose to water pump.

(3) Mount #2 water inlet connection flange with two nuts with torque of 15N.m.

18. Mount oil dipstick and guide tube.

(1) Mount new O ring onto the connection port of guide tube.

(2) Smear soap water onto O ring for easy pushing.

(3) Push the oil dipstick guide and dipstick into position and fixed with bolts with torque of 9.3 N.m (Fig. 152).

19. Mount intake manifold

(1) Mount intake manifold (with new gasket) with 7 bolts and two nuts, in several equal operations with a torque of 19 N.m.

(Fig. 153)

A pressure sensor shall be mounted onto the air intake manifold with two bolts

20. Mount fuel injector and fuel delivery pipes

(1) Smear a thin layer of gasoline onto the two new O-rings, and mount them onto the fuel injector (Fig. 154).

(2) Mount the four fuel injectors onto the delivery pipes when rotating them.

(3) Place the power resource union of injector upward.

(4) Mount the injector with four clips (Fig. 155).

(5) Mount two spacers onto the intake manifold.

(6) Mount the compo. of injector and delivery pipe onto the correct position on the intake manifold (Fig. 156)

Fig. 150 Smear sealant to cylinder head

Fig.151 Mount new gasket for #2 water inlet flange

Fig. 152 Mounting new O-ring to the port of dipstick guide Fig.153 Installing intake manifold

Sealant

Protrusion

New O-ring

64

(7) Make sure the rotation of injector is stable. If not, it may be most likely caused by incorrect mounting of O-ring. There-

fore, replace such O-ring (Fig. 157).

(8) Fasten the two bolts on the intake manifold used to fix the delivery pipes, with torque of 15 N.m. (Fig. 158)

21. Connect the inlet fuel hoses to delivery pipes. The torque for fastening two bolts is 29N.m (Fig. 159)

Connect the inlet fuel hose of Jl481Q/MR481QA to the delivery pipe and clip it with two clips.

22. Connect the engine wire harness. Fix the wire harness support with two nuts (Fig. 160).

23. Mount water bypass hoses and fuel return hoses.

(1) Use two bolts to install water bypass hoses and fuel return hoses onto intake manifold with torque of 10.2 N.m.

Fig. 158 Fasten the bolt on the intake manifold that fixes the pipe Fig. 159 Connection between the fuel hose and pipe

Fig. 155 Method of fixing injector onto the delivery pipe

Fig. 154 Smear a thin layer of gasoline onto

each side O-rings when mounting injector

Fig. 156 Method of mount injector and

transmission pipe to intake manifold

New O-ring

ROTATING

UPWARD

Fig. 157 Check whether O-ring of injector is correctly mounted

65

(2) Connect fuel return hose to fuel pressure regulator. (Fig. 161)

4. Use two bolts to fix air intake manifold support stay.

Torque applied onto 12mm head bolt shall be 21 N. m.

Torque applied onto 14mm head bolt shall be 44 N. m.

25. Mount throttle body

(1) Install new gasket onto the flank side of intake manifold (Fig.162), the protruding side of gasket shall face downward.

(2) Connect two cooling water hoses onto the throttle body.

(3) Mount the throttle body onto the intake manifold with two bolts and nuts with torque of 20N.m (Fig. 163).

(4) Connectors: throttle position sensor(1), connector of ISC (idle speed control) valve (2) (Fig. 164)

26. Mount water inlet port and its shield

(1) Completely remove the old filling material in the water intake. There shall be no impurities or oil stains.

(2) Fill the sealant into the slot on the shield.(Fig.165)

Fig. 160 Fixing engine wire support Fig.161 Connect fuel return hose to pressure regulator

Fig. 163 Mount throttle body onto intake manifold

Fig. 164 Connect throttle position sensor to ISC connectors Fig. 165 Smear sealant to the water inlet shield

Fig. 162 Mount new gaskets onto the throttle

body and connect to water bypass hose

Sealant

Sealant Diameter 2-3

mm

Downward

Cooling water
bypass hose

(1)

(2)

66

(3) Use two bolts and nuts to connect water inlet port with its

shield (Fig. 166), with torque of 22 N.m.

(4) Connecting of two water bypass hoses.

27. Install RH bracket of engine, with torque of 30 N.m.

28. Mount ignition control device, including phase sensor and

ignition coil for MR479Qengine.

(1) Set the #1 cylinder to: TDC of compression stroke. Rotate the

crankshaft clockwise so that the gap of intake camshaft is

positioned as shown in Fig. 167.

(2) Mount phase sensor and seat(Fig. 168)

(3) Mount ignition coil(Fig 169)

(4) Connect the high voltage wire

(5) Adjust the ignition timing

29. Install water outlet pipe

(1) Completely remove old seal material in the cylinder head and connection flange. There shall be no impurities and oil

stains on the surface.

(2) Smear the sealant into the slot of water outlet connection flange (Fig. 170).

(3) Use two bolts to mount the water outlet connection flange (Fig. 171), with torque of 22N.m.

30. Mount exhaust manifold

(1) Use two bolts to mount the lower heat isolation cover onto the exhaust manifold, with torque of 9.3 N.m.

Fig. 168 Phase sensor and seat

Fig. 169 ignition coil

Fig. 167 Set the TDC of #1 cylinder in compression stroke

Fig. 166 Install RH bracket of engine

Clearance

67

(2) Use five nuts to mount the new gasket and air exhaust mani-

fold. Tighten the nut with several equal operations. (Fig. 172),

with torque of 34 N.m.

(3) Use two bolts to assemble the manifold support stay.

Tighten the bolt in an alternate way in several equal operations,

with torque of 59 N.m.

(4) Use four bolts to fix the heat isolation cover, with torque of 17

N.m.

31. Mount AC generator

32. Mount bracket for A/C compressor

33. Mount A/C compressor

34. Make connection of engine wire harness.

(1) Mount the wire harness support with bolts.

(2) Connect the following wires and clips

a. Connector of AC generator

b. Wire of AC generator

c. Connector of oil pressure switch

d. Clip of wires.

e. Wires of AC compressor

35. Mount AC compressor belt

36. Mount water pump pulley and driven belt of AC generator

37. Filling engine oil

38. Filling engine coolant

After assembling clutch and gear-box, the whole engine power train can be assembled into the vehicle.

Fig. 170 Sealant of water outlet connection flange

Fig. 171 Fastening the water outlet connection flange Fig.172 Mounting exhaust manifold

Sealant

Seal diameter of 2-3 mm

68

The function of piston & connecting rod mechanism is to convert pressure of working substance in the cylinder into power

by rotation of the crankshaft and flywheel assy. Piston & connecting rod mechanism mainly consists of piston, piston rings,

piston pin, connecting rod body, connecting rod cap, connecting rod bolts, nuts and connecting rod bushing. The disas-

sembled piston & connecting rod mechanism of engine is illustrated in Fig. 173. The consolidation degree and power per

unit piston area of engine are high. The structures of canopy piston top, minus offset and semi-floating piston pin allow less

motor noise and more working flexibility.

Chapter 4 Piston & Connecting Rod Mechanism

Because short piston and low compression height helps to lighten piston weight and reduce reciprocating inertial force,

both of the compact engines can run at a higher speed.

Two gas rings and one oil ring is fitted on the piston head. The height of the first gas ring is 3mm and that of the secondary

one is 2.5mm. Eight oil feed-back holes of 2mm in diameter distribute symmetrically at the both sides of the pin hole on the

bottom of oil ring slot, and a piston pin lubricant track is designed on piston pin seat, which permits the continuous suction

of lubricant. To achieve fine thermal conductivity, heating surface on the piston top introduces the structure of smooth

transition, and a big transition circular is adopted to connect top plate and ring belt.

1. Structural Characteristics of Piston, Piston Pins and Piston Rings

1. Piston

The main functions of piston are to undergo high temperature and high pressure of working substance in cylinder, keep

airtightness of cylinder together with piston rings, and transfer heat to cylinder walls. The piston used in the engine is made

of cocrystallization aluminum-silicon alloy. Integral and tin-coated, it reduces the possibility of napping. Combustion cham-

ber, formed by piston top and cylinder cap, provides a large room for extruded gas. The projection of combustion chamber

offers a good shape for organizing whirl currents of extruded gas, and advances the features of high thermal efficiency,

small chill area and low knocking. The structure of piston is shown as Fig. 174.

Section 1 Construction of Piston & Connecting Rod Mechanism

1.First gas ring 2.Secondary gas ring 3.Combination oil ring 4.Piston pin 5.Piston

6.Connecting rod 7.Connecting rod bushing 8.Connecting rod cap 9.Connecting rod nut

Fig 173 Disassembled piston & connecting rod mechanism Fig. 174 Structure of piston

69

Because of high mechanical and thermal loads and complicated stress distribution on the piston, it’s hard to control the gap

width between piston and cylinder body. For achieving steady control of the gap, the piston of engine adopts the structure

of drum skirt and elliptic cross section, with long axis vertical to the pin hole and short axis parallel to it.

Piston uses an intact strengthening rib to transfer force. Its pin seat sinks into the rounded outer piston surface by 9mm,

reducing support distance between piston pins and weakening deformation of piston pins and pin seat. Apart from that, an

appropriate lead angle at the internal edge of pin seat lightens edge loads on the pin seat, the unequal thickness of pin seat

and biasing of outer circle’s center towards piston top by 2cm strengthen the upper half piston which endures larger stress.

To eliminate the destroying stress caused by heat expansion of piston skirts and deformation of piston’s pin seat, concavi-

ties are drilled under the piston pin holes, with one concavity in each skirt.

Forward marks on piston top and group marks on skirt recesses provide ease of mounting and fitting.

2. Piston pin

Piston pin connects piston and connecting rod, and endures various loads including pull, thrust, wallop caused by alternat-

ing movements of connecting rod and pin seat. Periodical changes of loads on connecting rod small end and pin seat, as

well as slight glide of piston pin in pin hole, lead to bad conditions of abrasion and lubricating on all parts of piston pin. The

inner hollowed piston pin of engine is made of low carbon alloy steel. After treatments of outer-surface carburization, preci-

sion grinding and polishing, it acquires sufficient rigidity and intensity, fine wear resistance property on surface and excel-

lent impact toughness on central part. In the semi-floating structure, magnitude of interference between connecting rod

small end and pin varies from 0.12mm to 0.003mm, while oil film thickness between pin and pin seat varies from 0.002mm

to 0.013mm. Such structure has the advantages of omitting copper sleeves and piston pin clamp rings, reducing connect-

ing rod small end width and lengthening pin seat. But connecting rod must be mounted at the temperature of about 100

o

C

or be squeezed by press machine at the temperature of -40

o

C in cold state, which will cause difficulties in disassembly.

3. Piston ring

Piston rings of engine include two gas rings and one oil ring connected by flat ends.

The main functions of cylinder are to prevent the exchange of burned gas with high temperature and high pressure in

cylinder and waste gas in crankshaft case, and transfer most heat from piston top to cylinder wall in order to minimize heat

in piston head and piston skirt and minimize deformation of piston.

The cross section of the first gas ring is illustrated as Fig. 175. It’s a symmetrical barrel-shaped ring with small interface and

good leak tightness. It also possesses fine lubrication property and can provide constant lubricant films both in its upward

movement and downward movement. The rounded outer surface of the first gas ring is nitridation treated and the rest

surfaces of it are bonderite. The first gas ring is 2.7±0.1 in thickness and 1.2 in height. Free ends distance is 10mm

and radial elasticity is 18.4-27.6N. Back clearance after mounting is 1.25mm.

The cross section of the secondary gas ring is illustrated as Fig. 176.It’s a conic ring with pitch of 1 . It can provide

lubricant film in its upward movement while scraping lubricant in its downward movement. The secondary gas ring is made

of nodular graphit castiron or tungsten vanadium titanium alloy,and possesses good wear-in property, fine thermal stability

and excellent wear-resistance. Surfaces of the secondary gas ring are bonderite. This ring is 3.0±0.1 in thickness and

1.5 in height. Free ends distance is 13mm and radial elasticity is 18.4-27.6N. Back clearance after mounting is

1.3mm. A “π”sign for mounting is marked on the side of the ring, take care not to mount it in the reverse direction.

Fig 176 The cross section of the second gas ring

Fig 175 The cross section of the first gas ring

-0.010

-0.025

-0.010

-0.025

+30’
0

70

The main functions of oil ring are to scratch down lubricant splashing on
cylinder walls, return it to oil pan through the upside and downside gaps of oil
ring and the oil feed-back hole on spring gasket drain pan, as well as distrib­ute lubricant on cylinder wall evenly to reduce fiction and strengthen seal
property. The oil ring is a combination steel ring, consisting of two scraper
rings and one backing ring. The combination oil ring is 3 in height and

2.7±0.15 in thickness. The barrel-shaped scraper rings, which have chroming
surfaces and small contact surface, are made of tool steel. The tangential
elasticity of scraper rings is 34-51N and the backing ring is made of nickel­chrome steel. The cross section of the oil ring is illustrated as Fig. 177.The
structure of piston,piston pin and piston ring about JL481Q/ MR481QA are
the same principle and have a little differences in dimension.

II. Structural Characteristics of the Con-

necting Rod and its Bearing Shell

Fig. 178 Structural diagram of

Fig. 179 Structural diagram of

+0.024
0

-0.15

-0.20

Fig. 177 Cross section of combination oil ring

-0.05

-0.13

+0.018
0

1. Connecting rod

The connecting rod connects the piston pin and the crank pin to convert the reciprocating
inertial movement of the piston into rotational movement of the crankshaft. The connecting rod
includes the connecting-rod body, cap, bolts and nut. The connecting-rod body is shown in Fig.

178. The small end and big end of the connecting-rod bear rectilinear load with varying
strength and direction, while on each section of the body there exists adverse loads such as
alternating bending moment, shear, normal force and rectilinear load. The connecting rod of
engine, mould-forged with No. 40 fine steel, has its surface stress peened. The truncated
connecting rod structure, connecting-rod body and connecting-rod cap are fastened through
bolts. The center distance of the MR479Q connecting rod = 122±0.031mm, center distance
between the two bolt holes is 54±0.1mm, diameter of the big end is 43 The section of the
rod body is I-shaped, the big end of the connecting-rod cap has a thickness of 22 .
The center distance of the JL481Q connecting rod = 132.5±0.050mm, center distance between
the two bolt holes is 62±0.1mm, diameter of the big end is 51 .They will be processed
after it is assembled with the connecting-rod body. The connecting-rod body and connecting­rod cap have a recess respectively for positioning of the bearing shell of the connecting rod
during installation. In the big end hole of the connecting-rod body, there is an oblique oil hole
of 3mm in diameter, from which the injected lubricant cools and lubricates the piston. In the
meanwhile, the outlet of the oil hole is made in the form of a load relieving recess. For the
convenience in assembly, the connecting-rod body and cap carry a front end marking. The
connecting-rod cap is also marked with the grouping. For re-assembly, the parts need to be
assembled according to the numbers. The connection between connecting –rod and
connecting-rod cap of JL481Q is different from the MR479Q in that nut tightens to screw hole
directly.

2. Connecting-rod bearing shell

Engine has a double layer bearing shell, using 08F as the steel back and aluminum-based alloy
as the anti-friction layer. The total thickness at the middle of the bearing shell is 1.5 whereby
the thickness of the steel back layer is 1.22mm and that of the anti-friction layer is 0.28mm. To
avoid retreating or bulging of the bearing shell during assembly, on both sides of it there are
partial thin areas. The internal diameter of the JL481Q bearing shell d=48mm, and its width
b=17 . The proper width/diameter ratio (b/d=3/8) can prevent lubricant from flowing out from
both ends, and excessive load is avoided on the fringe as well. A positioning tongue and oil
reservoir ditch are punched at the orifice of the bearing shell. The thickness of the connecting­rod bearing shell is achieved by assembling in 3 groups in order to have a reasonable clearance
of the oil film.

-0.002

-0.014

0

-0.2

71

Fig. 180 Check the axial play of the connecting-rod

1. Dismantling and Inspection of the Connecting-rod and its Bearing

II. Assembly of the Connecting-rod and its Bearing

1. Check the axial clearance of the connecting-rod (Fig. 180)

2. Dismount the connecting-rod cap and check the oil film clearance(0.15

to 0.30mm).

Check the matching marks on the connecting-rod and the cap. Pay

attention to the installation marks during re-assembly.

Dismount the connecting-rod cap. Use a thicknes feeler gauge to measure

the oil film clearance at the widest point (Fig. 66):

Standard model: 0.020-0.051mm,

Model with expansion of 0.25: 0.019-0.065mm,

Max. oil film clearance is 0.08mm. In case of oil film clearance being

greater than the max. , replace the bearing. Polish or replace the crank-

shaft if necessary.

3. Remove the piston and the connecting-rod assembly

4. Dismount the connecting-rod from the piston (see Section II, Chapter II)

Section 2 Dismantling and Inspection of

the Connecting-rod and its Bearing

Fig. 181 Installation of the connecting-rod bearing Fig. 182 Assembling of the piston and the connecting-rod

Front end mark

(Recess)

Front mark

(Bulging)

1. Assemble the piston and the connecting-rod (Fig. 182).

(1) Paste engine oil on the piston pin and piston pin hole.

(2) With the front end marks of the piston and the connecting-rod on the

same side, push in the piston pin with the thumb.

(3) Press the piston pin into the piston when freezing -40°C or heating

up connecting rod to 100°C with a special tool.

2. Install the upper bearing (Fig. 181)

(1) Select the bearing before installation.

(2) Align the bulging part of the bearing with the recess of the

connecting-rod or its cap, and mount the bearing into the connecting-

rod and its cap.

3. Install the piston and

connecting-rod assembly

(Fig. 183)

(1) Slip a short hose over

the connecting-rod bolt to

protect the crankshaft

from damage.

72

(2) Press the pistons and connecting-rod assemblies with correspondingnumbers into the cylinders respectively, with the

front end mark of the piston facing forward.

4. Installation of the connecting-rod cap

Among the common faults of the piston there are wear, galling, ablation and deformation.

III. Technical Data for Common Repair of the

Connecting-rod and its Bearing (Table 5)

1. Piston damage

Section 3 Common Faults of the Piston Connecting-

rod Mechanism and Troubleshooting

Fig. 183 Installation of the piston and connecting-rod assy.

0.15-0.30mm

0.35mm

1.486-1.490mm

1.490-1.494mm

1.494-1.498mm

0.020-0.051mm

0.019-0.065mm

0.08mm

0.15mm

0.06mm/100mm

0.03mm/100mm

Standard

Max.

Standard

Mark 1

Mark 2

Mark 3

Standard

Increase by 0.25

Min

Max

Max

Max

Standard

Min

Axial play of the connecting-rod

Wall thickness at the middle of the Standard

connecting-rod bearing

Oil film clearance of the connecting-rod

Bending of the connecting-rod

Twist of the connecting-rod

External diameter of the connecting-rod bolt

Name Maintenance data

Front end mark (recess))

Push down

8.860-9.00mm

8.60mm

73

The greatest wear of the piston is the wear of the piston ring slot. Due to the pressure of the cylinder, the piston ring applies

a high pressure on the slot. Under the action of a high temperature and pressure, the first ring slot is worn most severely,

and the wear of the following ones decreases gradually. The clearance between the piston ring and the wall of the ring slot

can be measured with a thickness gauge. Ring slot clearance: permissible for the first slot: 0.020-0.055mm, for the second

slot: 0.020-0.055mm. In the case of the clearance being greater than the max., replace the piston. Furthermore, as wear is

likely between the piston pin and the pin hole, causing a loose engagement between the two. In the case of abnormal

noise, if the piston can move back and forth on the piston pin, then, replace the whole set of piston and piston pin

In the case of small metallic chips existing between the piston and the cylinder wall, high temperature caused by friction

makes such chips contact each other, and the relative movement cuts off the thermo-welded locations so that the friction

surface becomes rough and galling scratches appear. Among the causes for the galling are: a. Ineffective sealing of the

piston ring leading to increased leakage, overheated piston and damaged oil film. b. A narrow galling surface in the middle

of the main thrust surface indicates an excessive ellipticity. If there are wide galling surface in the middles of both thrust

planes, that indicates that the cylinder play is too small. c. If the galling takes place at the four 450 diagonal locations of the

center line of the piston pin, that indicates that there is a too tight match between the piston pin and the pin hole.

Serious galling or extremely poor piston lubrication is likely to lead to ablation. In such cases, replace the entire set of piston

assembly.

II. Damage of the Piston Pin

III. Broken or Ablated Piston Ring

Table 6

Among common faults with the piston pin are tubercular corrosion, fleck and bending deformation due to wearing as well

as deformation of out-of-round. If the cylindricity of the piston pin is over 0.002mm and roundness is over 0.0015mm, then

replace the piston pin.

Common faults with the piston ring are break, wear, ablation and burr. When its end play or side play is too small, or the

frequency of its radial bouncing is not consistent with the natural frequency of the ring, the piston pin is likely to break.

Measure the end play and side play of the piston pin with a thickness gauge. For check of the end play, push the piston ring

into the cylinder at a position 97mm from the top of the cylinder block. Detailed data are given in the table below. In the case

of a too small end play, use a fine file. For check of the side play, install the piston ring to the piston. In the case of a too

small side play, adjust it by fine polishing. If the combustion chamber has an excessive temperature, engine oil glues, or

the cylinder has a poor lubrication, then, the piston ring is prone to ablation. See Table 6 for the maintenance data for the

piston ring.

First one
Second one
First one
Second one
Oil ring
First one
Second one
Oil ring

Standard

Standard

Max

Gap of the piston ring slot

Opening gap of the piston ring
MR 479Q,MR479QA
(within 78.70)

MR481QA,JL481Q
(within 81)

Name

Maintenance data

Maintenance data for the piston ring

1.05mm

1.20mm

1.10mm

0.2-0.5mm

In the case of piston deformation, just measure the ellipticity of the skirt of the piston 18mm (MR479Q)/16mm

(MR479QA) /20mm (MR481QA,JL481Q) from the piston bottom, in a direction vertical to the pin hole). If the deviation-

from the standard value exceeds 0.04mm, replace the piston.

0.020-0.055mm

0.2-0.4mm

74

IV. Damage of the Connecting-rod

Common faults with the connecting-rod are its bending and twist. Check the straightness of the connecting-rod, as shown

in Fig. 184 and 185.

Max. twist: 0.06mm/100mm

Max. bending: 0.03mm/100mm

In case of the max. twist exceeding 0.06mm, replace the connecting-rod assy.;

In case of the max. bending exceeding 0.03mm, make correction by using the connecting-rod correcting instrument;

Check the connecting-rod bolt: Install the lock nut for the connecting-rod bolt. Check the lock nut by turning it to the end

position with hand. If the lock nut can not rotate flexibly, measure the external diameter of the bolt with a vernier calipers.

Standard outer diameter is 8.860-9.00mm and min. outer diameter is 8.6mm. If the outer diameter is smaller than the min.,

then replace the entire set of connecting-rod bolt and nut.

Fig. 184 Check twist of the connecting-rod Fig. 185 Check bending of the connecting-rod

75

Fig. 186 Drawing of Crankshaft Assembly

T

he role of crank mechanism is to create torque by turning the reciprocate inertial movement of piston connecting-rod

into the rotary movement on its own so as to drive all the accessory systems and mechanism of engines in proper running

while the flywheel exports the net power. Engine drives the valve train through toothed belt, drives water pump, generator

through “V” belt. Crankshaft is also used to directly drive the oil pump. The crank flywheel assy. of engine is shown as

Fig. 186.

Chapter 5 Crank Mechanism

1. Crankshaft

The function of crankshaft is to receive the force from a connecting-rod, thus creating the torque rotating around its own

axes. Engine crankshaft is made of nodular cast iron, installed entirely with support, which has enhanced the rigidity and

bending strength of crankshaft.

The diameter of MR479Q 5-main bearing

journal is 48mm, the diameter of 4-

connecting-rod journal is 40mm. The

diameter of JL481Q main bearing journal

is 48mm.,the diameter of

Section 1 Structural Characteristics of

Crank Mechanism

1. Key 2. Crankshaft 3. Bearing shell 4. Thrust washer 5. Bearing cap 6. Main bearing cap bolt 7. Rear oil seal gasket 8. Rear oil seal retainer 9. Rear oil
seal 10. Rear end plate 11. Flywheel 12. Flywheel retaining bolt 13. Signal disc 14. Cylindrical pin 15. Dowel pin

F4

M1-2

M3-4

4

23

1

F2

Fig. 187 Balance weight of crankshaft

F3

F1

76

JL481Q connecting-rod journal is 48mm. All the cranks circle around the central main bearing journal to form mirror
symmetry. One-reciprocating inertia is mutually balanced with one-inertia torque. And two-reciprocating inertia and torque
are very small, which are generally omitted. Because all the cranks are symmetrically arranged with 180°, rotary inertia and
rotary inertia torque are balanced as a whole. But the bending torque inside the crankshaft is so large that all the cranks
are locally affected by bending. In order to relieve the bending torque between the crankshaft and the cylinder block, a
group ignition sequence of 1.4-2.3 is adopted, and meanwhile, there are 8 counterweights made at the opposite directions
of 8 cranks (Fig. 187). The centrifugal forces F1 and F4 at the two connecting-rod journals of No. 1 and No. 4 are equiva­lent to the centrifugal forces F2 and F3 at the two connecting-rod journals, in opposite directions. F1 and F2 form moment
of couple M1-2 and F3. F4 forms moment of couple M3, also mutually balanced. But the two moments of couple have
provided bending load to the crankshaft while load on the main bearing shell is also increased so that main bearing journal
and main bearing shell are abraded slantingly. After counterweights are added, the load on main bearing shell is reduced
while the running stability of engine is improved.
In order to lubricate the connecting-rod journal, there is an oil hole with diameter of 5mm drilled from main bearing journal
to connecting-rod journal. The first main bearing journal oil hole is drilled through the first connecting-rod journal, the
second journal oil hole through the second connecting-rod journal; the fourth main bearing journal through the third
connecting-rod journal. The fifth journal oil hole is drilled through the fourth connecting-rod journal; the third main bearing
journal is without oil hole. The oil hole on the crank pin is provided at the area 220 in front of rotating crank plane, and at
the hole opening area is the low load area as far as the transition round angle of two journals. The oil hole of main bearing
journal is arrayed at the low load area. All the hole openings are polished and chamfered.
MR479Q Crankshaft stack-up degree ∆ = 9.5mm. Thickness of crank arm = 16.75mm. Width of crank arm =70mm.
MR479QA/MR481QA Crankshaft stack-up degree ∆ = 5.5mm. Thickness of crank arm = 16.75mm. Width of crank arm
=76mm. JL481Q Crankshaft stack-up degree ∆ = 5.25mm. Thickness of crank arm = 16.75mm. Width of crank arm
=76.5mm. Crank is good in rigidity and strength. The crank arm takes the shape of ellipse so that the stress is evenly
distributed, resulting in a good bending strength and torsion rigidity. Meanwhile, thickness of crank arm is transited through
the shoulder. In order to relieve the crankshaft’s weight and reduce the unbalanced properties of crankshaft rotating, the
shoulder of crankshaft adopts a big angle. In order to reduce the stress centralization between cranks and main bearing
journal and between crank and connecting-rod journal, R2 bevel is used for transition at the connecting area and roll-press
polishing treatment is provided. Crankshaft is nitridation treated in order to increase its abrasive resistance. In order to
avoid axial crankshaft displacement, two crankshaft thrust washers are placed on either side of the central main bearing.
Engine has a key slot in the front of crankshaft, through which peripheral locating and transmitting of the torque can be
carried out for crankshaft timing gear and crankshaft belt. In the forefront of crankshaft there is a hole of M12x1.25-6H and
32 in depth. Using the bolt, it can tighten the crankshaft pulley. The bearing shoulder on the side and in front of the first
main bearing journal is milled with 4 planes. The ridge among the planes can directly drive the oil pump. On the back end
of crankshaft there is a flange with diameter of 70. The end face is provided with 6 drilling holes of M10x1.25-6H, in which
the locating hole with diameter of 13 is used as a mounting mark for alignment with the locating hole on the flywheel.
For easier selection of bearing shell for assy., there are three groups separately arranged in terms of diameters of main
bearing journal and connecting-rod journal. Each group is separately marked with red, yellow and green. The mark of
crank pin is at the big chamfer of cranks, and the diameter mark for main bearing journal is at the w-type counterweight.

II. Main Bearing

Main bearing of engine includes upper bearing harf and lower bearing harf. In order to achieve a reasonable oil clearance,
there are 5 groups in terms of the total thickness of bearing center.
Upper bearing half and lower bearing half are of the steel-backed—wear-reducing layer structure. The steel-backed mate­rial is 08F, wear-reducing layer is aluminum base alloy. The total central The steel-backed material is 08F, wear-reducing
layer is aluminum base alloy. The total central thickness is 2 ,in which aluminum base alloy is 0.3±0.1 in thickness
and bearing 20mm in width. Upper bearing has a filler hole of 6mm in diameter, and an oil reservoir of 4mm in width and
1mm in depth in the middle so that it is easy for the lubricant to enter the oil hole of main bearing journal. On the back of
upper bearing and lower bearing there is a locating recess punched. To avoid bearing bulging due to inner shrinkage during
assembly, there is a thinning area prepared on the inner sides of two ends of bearing.

+0.017
+0.002

77

III. Crankshaft Thrust Washer

The crankshaft axial positioning of MR479Q engine adopts the structural form of two-half-circle thrust washer. Crankshaft

thrust washer is also of a steel-backed-wear-reducing-layer structure. Steel-backed material is 08F, wear-reducing layer

material is of high-tin aluminum alloy. The crankshaft thrust washer is 2.5 thick. On the working faces of two thrust

washers, oil holes are milled respectively. Crankshaft thrust washer is positioned by way of locating tongue.

IV. Flywheel

The role of flywheel is to restrict the revolving unevenness with the flywheel, storing part of the energy done by the engine

so as to ensure that incoming air compression and exhaust stroke run smoothly and overcome the short time overload. The

start of the end face of engine can serve as an active friction face to export the power.

Engine flywheel is made from gray cast iron with 254mm in diameter. The flywheel is thick outside and thin inside to reduce

its weight. The outmost of the flywheel end face has 6 mounting holes for M8-6H clutch and 3 holes (?8 ) for dowel

pin holes. There are 5 mounting holes for flywheel and 1 hole for positioning the flywheel. Revolving-speed toothed disc

installed on the outer peripheral of flywheel is interference fit with the flywheel. The peripheral is positioned by dowel pin.

There are totally (60-2) teeth on revolving-speed toothed disc, and there is a “T” mark on the disc end face. The “T” mark

corresponds to the locating hole and crankshaft 1.4 crank plane. Counterclockwise, there is an absence of 2 teeth in the

part of 1320 in front of “T”. Because of the speed sensor installed in the centerline of cylinder block, when speed sensor

corresponds to the missing teeth, it has created a pulse signal of speed sensor to ECU . In the part of 1140 in front of “T”,

the falling edge of the teeth starts to trigger the controller to make the timer work.

1. Disassembly for Inspection

1. Detaching of flywheel

Before disassembly, use a dial gauge to check the slanting degree (as shown in Fig. 188). Disassemble the rotation speed

sensor and its support. Detach 6 bolts and the flywheel.

2. Disassembly of crankshaft

(1) Check the radial clearance of crankshaft

Section 2 Disassembly & Maintenance of

Crank Mechanism

Fig. 188 Check the Slanting Degree Fig. 189 Test the Radial clearance of Crankshaft

-0.03

-0.06

+0.015
0

78

Standard radial clearance: 0.06-0.22mm. The Max radial clearance: 0.30mm

In case that the radial clearance is larger than the maximum value, replace the whole set of thrust washers. The thickness

of thrust washer: 2.5 mm.

(2) Disassemble the main bearing cap and check the oil clearance

a. Follow the procedure in the table, unscrew and take down the bolts with several operations (Fig. 190) starting from two

sides first and then in the middle.

b. Use the disassembled bolts to rock the main bearing cap with prying actions, and take down the main bearing cap, lower

bearing shell and thrust washer (Fig. 191);

c. Take out the crankshaft with lifting action (Fig.192);

d. Clean all the main bearing journals and main bearing shells;

e. Check whether all the main bearing journals and main bearing shells have dents and flaws on the surface (Fig. 193). In

case that the main bearing journal or main bearing shell are damaged, replace the bearing shell. When necessary, grind

the crankshaft.

f. Mount the crankshaft onto the cylinder block: pass the plastic clearance gauge through each journal to measure the oil

film clearance (Fig. 194).

g. Install the main bearing cap (Fig. 195) first in the middle and then two sides, and tighten evenly the bolts diagonally with

the torque of 60Nm(MR479Q,MR479QA)/70Nm(MR481QA)/80Nm(JL481Q)

Fig. 190 Detaching main bearing cap bolts

Fig. 192 Taking-out crankshaft

Fig.191 Detaching main bearing cap

Fig.193 Inspecting crankshaft

-0.03

-0.06

79

Fig. 194 Measuring Oil clearance Fig.195 Mounting main bearing cap

Fig.196 Measuring Oil Film Clearance

Fig.197 Illustration of Grouping Number of

Crankshaft Journal & Bearing Shell Dimensions

NO.1

1, 2, 3, 4 and 5

Plastic oil clearance gauge

NO.2

NO.3

NO.4 NO.5

NO.1 NO.2 NO.3 NO.4 NO.5

h. Take down the main bearing cap and measure the oil
clearance in the section of largest width.󰵪See Fig.196󰵫
Oil clearance:
Standard: 0.015-0.033mm
Enlarged size by 0.25: 0.016-0.056mm
Max. oil clearance: 0.10mm
If the oil clearance is larger than the maximum value, replace
the bearing shell. When necessary, grind or replace the
crankshaft. If the cylinder block parts are changed, the
standard clearance of bearing shell should be 0.015-

0.045mm.

If standard bearing shell is used, it is necessary to use those
with the same number. If the number of bearing shell cannot
be determined, it is possible to sum up the size numbers on
cylinder block and crankshaft and then choose the number of
bearing shell equivalent to the above sum, so as to ensure
accuracy of selection. Totally, there are 5 standard bearing
shell sizes, marked with “1”, “2”, “3”, “4” and “5” respectively
(Fig. 197, Table 7).

80

For example, cylinder block No.“2” + crankshaft No. “1” = total number “3”, i.e., use No. 3 bearing shell.

For standard bearing shell sizes, see Table 1.

(3) Detaching crankshaft

Take out crankshaft with lifting action: remove the main bearing shell and upper thrust washer from the cylinder block.

(4) Checking the radial run out of crankshaft

Place the crankshaft on the V-type block. Use micrometer to measure the radial jumping (Fig. 55) in the middle of journal.

Max. radial run out: 0.03mm.

If the radial run out is larger than the maximum value, replace the crankshaft.

(5) Checking main bearing journal and connecting rod bearing journal.

a. Measure the diameters of each main bearing journal and connecting rod bearing journal (Fig. 56);

If the diameters are not up to the standard, check the oil clearance. When necessary, grind or

replace the crankshaft.

b. Check the taper and degree of roundness of each main journal and connecting rod bearing journal;

Max. taper and degree of roundness: 0.02mm.

If the taper and degree of roundness is larger than the maximum value, replace the crankshaft.

II. Assembly

1. Installing Crankshaft

(1) Install the main bearing

a. Align the protrude portion of main bearing (upper harf) with the recess on the cylinder block

bearing seat while pushing 5 upper bearing shell through (Fig. 57, 58);

b. Align the protrude portion of lower bearing shell with the recess on the main bearing cap

while having 5 lower bearing shell pushed through (Fig. 59).

(2) Install thrust washer (Fig. 60)

Place two crankshaft thrust washers under the No. 3 journal of air cylinder block with oil groove facing outside.

(3) Put the crankshaft onto the cylinder block.

(4) Install Main bearing cap and thrust washer

a. Place 2 crankshaft thrust washers onto No. 3 main bearing cap to make the oil groove face

outside (Fig. 61);

b. Place 5 main bearing caps on the proper position (Pay attention to the front mark), (Fig.62);

c. Apply a thin layer of engine oil under the head of the main bearing bolts and at the thread;

tighten evenly 10 bolts diagonally from the middle to both ends.Torque:

(MR479Q,MR479QA)60N.m.(MR481QA)70Nm.(JL481Q)80Nm.

Finally, check the crankshaft radial clearance.

Table 7

123

1

4

2

5

0

3

2

4

1

3

0

2

2

3

1

2

0

1

Dimension Grouping

Cylinder

block

Crank-

shaft

Bore Diameter of
bearing seat

Diameter of Main
bearing journal

Bearing shell required

Grouping of Crankshaft Joumal & Bearing Shell Dimensions

81

III. Commonly-used Servicing Data (Table 8, 9 )

2. Install flywheel subassembly

Align the position sleeve hole on flywheel with the position sleeve hole on the back face of

crankshaft. Evenly tighten the bolts diagonally for several times. Torque: 78N.m.

How to select the connecting-rod bearing : When the connecting-rod big end bore, connecting-rod journal and connecting­rod bearing have the same color, it is ready for assembly.

Table 8

Table 9

Table 9 -1

Group Sizes (mm)

52.025-52.031

52.031-52.037

52.037-52.043

47.994-48.000

47.988-47.944

47.982-47.988

2.002-2.005

2.005-2.008

2.008-2.011

2.011-2.014

2.014-2.017

Mark

Red

Yellow

Blue

Mark

Red

Yellow

Blue

Wall thickness of connecting

-rod bearing (mm)

1.5

-0.010

-0.015

1.5

-0.005

-0.010

1.5

00000

-0.005

Connecting-rod

journal (mm)

?48

00000

-0.006

?48

-0.006

-0.012

?48

-0.012

-0.018

Connecting-rod

big end bore (mm)

?51

+0.006

0

?51

+0.012

+0.006

?51

+0.018

+0.012

Wall thickness of connecting

-rod bearing (mm)

1.5

-0.010

-0.014

1.5

-0.006

-0.010

1.5

-0.002

-0.006

Connecting-rod

journal (mm)

?40

-0.010

-0.015

?40

-0.010

-0.015

?40

-00000

-0.05

Connecting-rod

big end bore (mm)

?43

+0.008

0

?43

+0.016

+0.008

?43

+0.024

+0.016

Name

Inner dia. of main bearing

journal of

cylinder block

Dia. of crankshaft main

journal

Central wall thickness of

standard

main journal & bearing

Group number

“1”

“2”

“3”

“0”

“1”

“2”

“1”

“2”

“3”

“4”

“5”

Grouping Data of Connecting-rod Journal and Bearing(JL481Q)

Servicing Data of Main Bearing Journal and Bearing shell

Grouping Data of Connecting-rod Journal and

Bearing(MR479QA,MR479Q,MR481QA)

82

1. Cracking & Fracture of Crankshaft

To check the cracking of crankshaft: by oil-soaked knocking, that is to immerse the crankshaft in the kerosene for a while

and then take out and wipe it dry. Spread some white powder onto the crankshaft and hammer its non-working face. After

vibrating, if oil stain appears, it proves the existence of cracking. Magnetic inspection: magnetize the parts through

magnetic inspector. If the parts are cracked, the magnetic pole will appear in cracked area. If you spray some pulverized

irons on the parts, the iron powder would be absorbed on the cracked area. So that the crack becomes easily visible. But

after the magnetic inspection, it is necessary to demagnetize it.

Once the crankshaft is cracked, have it replaced. If bending deformation appears in the crankshaft, apply a cold press

rectification or cylinder block rectification to repair it.

II. Wear of Flywheel Working Face and Damages to Gear Ring

1. Normally, when starting the engine, the flywheel gear ring and starter pinion easily collide with each other or have poor

engagement between the two teeth, thus easily leading to wear and damages to the teeth.

a. When the teeth of gear ring are worn on one side, turn it over for further use. The gear ring detaching or assemble needs

heating. After it is repaired and assembled, it is necessary to provide interference for the flywheel gear ring.

b. If any single tooth is damaged, use oil stone to repair and grind it. If serious wear or teeth damages take place on both

sides of gearing ring, it is possible to repaire by stack welding.

2. If the working face of flywheel wears or is grooved with depth over 0.5mm, it is proper to apply polishing or polishing after

finish-machining. If the wave depth is not over 0.5mm, it is allowed to have two ring grooves. After machining, the thickness

of gear should not be less than new flywheel teeth for over 2mm.

Section 3 Disassembly & Maintenance of

Crank Mechanism

83

Engine valve train is made up of camshaft timing drive and valve mechanism. The camshaft timing drive mainly includes

crankshaft timing pulley, guide wheel, crankshaft timing belt, camshaft timing belt, driving gear, sub gear, gear spring, drive

gear, intake and exhaust camshaft, and valve tappet, etc. The valve mechanism mainly includes valve seat insert, valve,

valve guide, spring retainer, and keeper, etc. Make-up of valve train is shown in Fig. 198

Chapter 6 Valve Train

I. Make-up of Valve Train

Section 1 Make-up of Valve Train & its

Design Features

Fig. 198 Schematic Diagram of Valve Train Assy

1. Filling adjusting shim 2. Valve tappet 3. Spring retainer 4. Valve spring 5. spring seat 6. Valve guide bushing 7. Valve 8. Exhaust camshaft 9. Tension

spring 10. Tensioner 11. Crankshaft timing pulley 12. Pulley 13. Camshaft timing belt 14. Snap ring 15. Wave washer 16. Camshaft sub gear 17. Camshaft

gear spring 18. Driving gear 19. Drive gear 20. Intake camshaft 21. Oil seal 22. Keeper 23. Timing belt

84

II. Characteristics of Valve Train

Each cylinder has 4 valves, laid in two columns. The intake path takes up a relatively large area and as a result, this

increases the rotation speed at maximum power, rotation speed atmaximum torque and its litre power, and decreases the

thermal load of the exhaust gas.

The DOHC (Double Overhead Camshaft Valve train) construction reduces the height of the cylinder head, and facilitates

the installation of the intake pipes. It also features low motion mass, high rigidity, high natural frequency and good high-

speed property.

The transmit mechanism adopts serrated belt transmit and helical gear with the auxiliary gears, featuring longer transmis-

sion distance, smooth movement, low noise level and cost.

Its excellent cam shape and motion pattern elevate inflation efficiency, and assures a reliable and low-noise level opera-

tion at high speed.

1. General

Valve timing refers to the rotated angle of crankshaft corresponding to the top and bottom dead centers at the moment of

opening and closing the valves of intake and exhaust in each engine cylinder. Generally, it is illustrated with a loop diagram.

In theory, the intake valve should be opened at the moment that the piston reaches the top dead center and closed at the

moment that the crank reaches the bottom dead center, and the exhaust valve follows a reverse pattern. However, due to

the high rotation speed of engine, each stroke of piston is completed in such a short time that makes it impossible to get

adequate air intake, clean exhaust, and hence leads to lower power. Therefore, the actual moments of opening and closing

of valves do not correspond to the top and bottom dead centers, but in an earlier time for opening and a later time for

closing.

In general, different engines have different timing. The best one is chosen according to the experiment results. Once the

timing is chosen, the angle between the intake cam and the exhaust cam of the same cylinder and the marks of meshing

engagement for each timing gear can be determined. Then, assemble the timing gears according to the marks to achieve

the selected timing.

For the transmit gear and the sub gear of the engine, there are two marks respectively on their front sides. One is the timing

mark. When two timing marks overlap, it indicates that the piston is in the top dead center of its compression stroke.

Another is installation mark, vertical to the timing mark. For the transmit gear, the installation mark comes first clockwise

and is nearly right above the camshaft fixing pin. For the sub gear, the installation mark comes first counterclockwise.

II.Valve Timing Diagram

The valve timing diagram for engine is shown as Fig. 199. The intake valve is opened before reaching top dead center to

assure that the intake valve has been opened fully in the beginning of the intake stroke, thus the combustible gas mixture

can enter into cylinder smoothly. The intake valve is closed sometime after reaching BDC so that the combustible gas

mixture may continue to enter into the cylinder in the early compression stroke by making use of inertia and pressure differ-

ence. The exhaust valve is opened before reaching the BDC (late power stroke). High pressure in the cylinder forces out

the exhaust gas and thus prevents engine from overheating. After reaching TDC, the exhaust gas can still be drained by

making use of inertia of exhaust gas.

Section 2 Valve Timing

85

Intake

Exhaust

IO

IO

BDC

TDC

EC

EC

1. Make-up of Valve Train Assy. and its Features

The assembly is designed to open and close the intake and exhaust valve according to the planned time and ensure that

they have enough lift stroke and follow the stipulated rules.

1. Crankshaft timing pulley

Crankshaft timing pulley is made from die-casting of powder metallurgy: tooth form, hole and keyway are made at the same

time without the requirement of machining. On the parts there is “V” type timing mark. When assembling and calibrating

valve-timing diagram, it is necessary to align it with the timing mark on the housing of oil pump. There are a total of 24 teeth

on crankshaft timing pulley.

2. Camshaft timing pulley

Section 3 Make-up of Valve train

Assembly and its Features

Fig. 199 MR479Q Engine valve-timing diagram

86

Camshaft timing pulley is also made from die-casting of powder metallurgy with 48 teeth in total. Two dowel pin slots.

During assembly, it is proper to encase the dowel pin slot on the side with “K” mark into the camshaft dowel pin. The

round-hole made in the center of lateral rib with “K” mark should be aligned with the “U” marking on the camshaft bearing

cap when calibrating valve-timing with the camshaft timing belt pulley axially fastened by bolts.

3. Timing belt

With 3-layer structure and 117 teeth in total, the belt is made of butadiene styrene rubber, the mid-layer being polyester

thread with low-expansion and low amount of distortion, and the canvas layer being the synthesis of cotton and synthetic

fiber. It has good heat resistance and abrasive resistance. With low transmit torque, the timing belt has a long life.Normally,

the timing belt shall be replaced after 120, 000 km of use. Meanwhile, in order to avoid teeth run-out in driving, there is a

tensioner on the back of the loosened part of the belt, which can provide a certain pre-tension to the belt. When adjusting

the deflection of toothed belt, it is possible to alter the pre-tension of tension spring by changing the position of tensioner

relative to tightening bolt. After adjustment, fasten the bolts.

4. Camshaft

Engine camshaft is made of the chilling alloy cast iron with an nitrogenized surface. It has high strength and good abrasion

resistance. The split bearing seat without lining is of full supporting structure, featuring good rigidity. On the intake and

exhaust camshaft there are 8 cams and 5 journals. The center to center spacing of intake and exhaust camshaft for each

cylinder is respectively 34mm and 36mm. Axially, It is positioned through single directional shoulder. As driven by bevel

gear, the exhaust camshaft is forced back and the intake camshaft is forced forward. The two forces are equal. The curve

in the section of cam lift consists of buffer and working section, in which wrap angle of exhaust cam buffer section is a little

larger than wrap angle of intake cam buffer, and the wrap angle of exhaust cam working section a little bigger than wrap

angle of intake cam working section. The MR479Q/MR479QA cam base circle is 34mm in diameter, intake cam lift is

7.81mm and exhaust cam lift 8.06mm. The center of camshaft is a main oil passage. Each journal has small holes leading

to the main oil passage so as to lubricate each camshaft journal and bearing seat. There is a groove on the back end of

exhaust camshaft, into which driveshaft of valve timing sensor can be inserted. It thus produces the signal for judgment of

cylinders and sends to ECU so as to carry out identification and control of two different TDC . The structure is simple and

reliable,.

II. Make-up of Valve Train Assembly and its Features

Valve train assy. is used to ensure the cylinder be well sealed.

1. Valve

Valve is one of the important elements to ensure the power, economy, reliability and durability of the engine. Intake valve

is of martensitic steel 4Cr9Si2, with good techniques, abrasion proof, anticorrosion and small expansion coefficient.

Exhaust valve is of austenite steel 5Cr21Mn98Ni4N, with good heat resistance. Its intake and exhaust valves are all

azotized. The intake and exhaust valve are shown as Fig. 200. The big end of intake valve head is 31mm in diameter and

the small end 27.372mm in diameter. The big end of exhaust valve head is 24.5mm in diameter and the small end

21.372mm in diameter. The ntake and exhaust valve employs a bigger Valve cone(45°) to provide a good airtightness. The

intake, valve neck bevel is 10°, with an arc of R6.5 for a transition. It has low intake resistance. Exhaust valve neck bevel

is 25°, and there is a big arc at the valve head and stem tip for a transition. It has a high rigidity.

The intake valve lift/diameter ratio is 0.252, the exhaust valve lift/diameter ratio is 0.329. The bottom of valve is flat and

valve stem is 6mm in diameter. The lateral force is large. The intake valve has a full length of 87.5±0.1mm and exhaust

valve has a full length of 87.5±0.15mm. Lock groove sinks in the form of arc. During assembly, keeper is embedded in form

of being raised on the stem lock groove. It can reliably lock the valve spring.

87

2. Valve seat insert

As shown in fig. 201, valve seat insert is used to

seal the cylinder by the close contact of its

internal conic surface with the valve conic

surface. Valve seat insert applies the powder

metallurgy steel, which has good cutting perfor-

mance and small thermal deformation. Valve seat

face is pressed into the cylinder head seat

through contraction. Its seal cone is processed

together with valve guide hole.

3. Valve tappet

Engine valve tappet adopts a short-cup form. It features good rigidity, light weight, large cam contact area, good lubrication

and reliability. Meanwhile, it facilitates the adjustment of the valve clearance. The material used for tappet is low-carbon

alloy steel.

4. Valve spring

Engine uses a single spring, cylindrical helical spring. The spring is 3.2mm in diameter with a central diameter of

21±0.1mm, and coiling wraparound ratio C = 6.56. The precompression quantity of intake valve spring is 7.8mm and that

of exhaust valve spring 7.5mm. To keep the spring in straight position under pressure, the two ends of the spring are

leveled in a range of 288 . It has 4.8 effective circles. The spring steel wire is made of 60SiCrVA, with good temperature

flexibility. The spring is processed with shot blast. In a free state, the total height of the spring is 39±0.3mm.

Fig. 201Seat Insert of Intake and Exhaust Valve

Fig. 200 Intake and Exhaust Valve

88

1. Valve tappet (see Section 2 of Chapter 3 for reference)

Measure the tappet bore of cylinder head with a caliper and its diameter with a micrometer caliper. The actual oil film clear-

ance is deduced by subtracting the tappet diameter from the tappet bore. If the oil film clearance is bigger than the

maximum value, the tappet shall be replaced. When necessary, replace the cylinder head.

III. Valve Train Assy.

1. Check the valve stem and guide

2. Check and grind the valve

3. Check and clean the valve seat

4. Check the valve spring

IV. Service of Timing Gear, Belt and Tensioner

1. Timing belt

While servicing the timing belt, be sure not to bend, twist

or upturn it. Keep the belt away from engine oil, water or

steam. Do not make use of the belt tension when

detaching the bolts of timing pulley of camshaft.

Pay attention to direction and position when reinstalling a

timing belt undertaking detaching.Therefore, you need to

make a mark during detaching . See Fig. 202.

II. Camshaft and bearing seat

1. Check the run-out of camshaft. If the radial run-out is larger than the maximum, replace the camshaft.

2. Check the peach tip height of cam, and if not up to the standard, replace the camshaft.

3. Check the camshaft journal. If the diameter is not up to the standard, check the oil film clearance.

4. Check the cam bearing for peeling-off or scorching. If damaged, it is necessary to replace the complete set of bearing

and cylinder head.

5. Check camshaft gear spring. If the free length is not up to the standard, have the gear spring replaced.

6. Check the oil film clearance of camshaft journal, and if it is larger than the maximum value, replace camshaft. If neces-

sary, replace the complete set of bearing and cylinder head.

7. Check the axial clearance of camshaft. If it is larger than the maximum, replace the camshaft. If necessary, replace the

cylinder head.

8. Check the camshaft gear clearance. If it is larger than the maximum, replace the camshaft.

Section 4 Service of Valve Train

Fig. 202 Alignment of compression TDC mark

89

V. Positioning and Installation of Valve Train

1. The installation of intake camshaft relative to the exhaust camshaft (shown as Fig. Assembly of cylinder head, Section

2, Chapter 3).

2. Installing belt tensioner tension spring

Install belt tensioner by bolts without tightening the bolts. After the tension spring is installed, push the pulley towards the

left as much as possible and then tighten the bolts (Fig. 203).

3. Installation of the exhaust camshaft relative to the crankshaft

Finding the position of TDC: to install crankshaft timing pulley, align the “V” mark on the pulley with the mark “ ” on the oil

pump body (Fig. 204)

Finding compression TDC position: align the dowel pin of camshaft with the dowel pin groove near the “K” mark of the

pulley before pushing in the timing pulley (Fig. 141). Use a spanner to fasten the hexagon head of camshaft and fasten the

retaining bolt with the torque of: 59N.m. Rotate the hexagon head of camshaft, so that the small hole near the “K” mark on

camshaft timing belt is aligned with the “U” mark on the No.1 bearing cap. (Fig. 205)

4. Installing timing belt

2. Tensioner

To check whether the belt tension pulley runs smoothly and flexibly. When necessary, replace it. Measure the free length

of tension spring. Free length: 36.9mm. Measure the tension of the spring with the specified length. The installing tension

(Length: 43.6mm): 34-38N. If the tension is not up to the standard, you need to replace the tension spring.

3. Timing gear

Check the tooth clearance. Check whether the tooth surface has point-corrosion and hard spots, etc.

Common Troubles:

If the timing belt breaks away too early, you should check whether it is properly installed and whether the deflection of belt

is proper. If the belt tooth is fractured or damaged, you need to check whether the camshaft or water pump is blocked. If

the belt is worn or damaged only on one side, you need to check the belt guide wheel and the positioning of all belt pulleys.

If the surface of the belt is apparently and abnormally worn or cracked, you should check whether the pin on tension pulley

is cracked on one side.

Fig. 203 Installing belt tensioner Fig. 204 Alignment of TDC mark

90

Check whether the mark on the timing belt placed during detaching is

properly aligned with the matching mark on the crankshaft pulley. If not,

you need to move the mesh portion on the timing pulley until it is

precisely aligned. Align the timing belt with the matching mark of crank-

shaft timing pulley. For details, see Fig. 143.

5. Check Valve Timing

Loosen the bolts of belt tensioner (see Fig. 144) and rotate crankshaft

clockwise. Check whether each pulley is aligned with the timing mark

(Fig. 206). Otherwise, you need to reinstall it. Adjust the deflection of

timing belt (fig. 148), and tighten the bolts of belt tensioner with the

torque of 37N.m (Fig. 207).

Fig. 205 Aligning Compression TDC Mark

Fig. 207 Fasten tensioner Fig. 206 Check timing mark

Table 10

V1. Common Servicing Data

Servicing Data

6.000-6.018mm

11.000-11.027mm

11.050-11.077mm

87.5±0.10mm

87.8±0.15mm

86.95mm

87.35mm

44.5°±15’

5.975-5.960mm

Standard

Enlarged size: 0.25

Intake

Exhaust

Intake

Exhaust

Intake

Exhaust

Inner diameter

Outer diameter (for servicing use)

Total length of valve

Valve cone angle

Valve stem diameter

Standard

Minimum

Valve guide

Valve

Servicing Data of Valve Train

Items

91

0.025-0.058mm

0.08mm

0.10mm

0.8-1.2mm

0.5mm

?1.2

39±0.3mm MR481QA,JL481Q

152-168N 176.8±10

31.000-31.025mm

30.970-30.985mm

0.015-0.055mm

0.07mm

0.032-0.085mm

0.040-0.095mm

0.11mm

0.035-0.072mm

0.10mm

24.949-24.965mm

22.949-22.965mm

0.03mm

41.72-41.80mm

41.97-42.05mm

42.645-42.685mm

41.99-42.030mm

0.020-0.200mm

0.30mm

17.02-17.10mm

Verticality deviation

Free length

Installing tension force when L is 31.7mm

Tappet bore diameter

Tappet diameter

Oil film clearance

axial clearance

Journal oil film clearance

Journal dia.

Circle run-out & eccentricity

Camshaft peach

tip height

(Base circle + lift )

Camshaft gear tooth clearance

Camshaft gear snap ring Free distance at end

Standard

Max.

Intake

Exhaust

Max.

Standard

Max.

No. 1 exhaust

Others

Max.

Standard

Intake

Exhaust

Standard

Intake

Exhaust

Standard

Max.

Intake

Exhaust

Intake

Exhaust

Standard

Min.

MR479Q MR479QA

MR481QA JL481Q

Valve

Valve spring

Valve tappet

Camshaft

Standard

Max.

Oil film clearance

Oil film clearance

Edge thickness

92

I. Valve leakage

It is possibly caused by:

(1) Wearing, scorching or leakage caused by rough surface (due to corrosion) at the interface between valve and valve

seat. If the working face seal belt of valve seat is worn to be wider than 1.4mm and has spots and pits, it is necessary to

ream and smoothly grind it. If the working face of valve is worn or scotched, you need to grind the working face. If the edge

thickness is less than 0.5mm, you need to replace valve. Whether valve is sealed tight or not can be examined by ways of

light or gas leakage, etc

(2) The valve clearance is too small and disappears after heating. Adjustment of clearance is required.

(3) Carbon deposits too much at the valve seat so that the valve seat is not tightly closed. Cleaning of the valve seat is

required.

(4) In case of bending and deformed valve stem or warped valve head, replace the valve. If the bending of valve stem is

within its allowance, correct it with a manual presser.

(5) If the valve becomes stagnant when moving up and down in the guide or sways inside the valve guide, replace with a

new valve guide. During the replacement, heat the cylinder head uniformly to 80°C to 100°C. Apply engine oil on the exter-

nal wall of the new guide before pressing it into the cylinder head. Meanwhile, it is required to check whether the inner

diameter of valve guide is proper or not. If not, ream it.

(6) If the valve can’t be closed tight due to deformation, replace valve seat ring.

(7) If valve spring breaks or losses elasticity, it shall be replaced.

III. Valve Seat Damage

Common troubles of valve seat are scorching, wearing and deformation. Once any scorching, spots, pits or obvious wear-

ing signs are found in the valve seat, it is necessary to ream or grind it. if it can’t be repaired, replace the cylinder head.

IV. Invalid Valve Spring

A shortened or inelastic valve spring may harm tightness. If the valve spring is not much shortened, it is possible to add

washers on the spring to recover its original length. If it is shortened excessively, replace it. If the spring nearly losses its

elasticity or deviates from upright position for over ?1.2, replace it.

II. Valve Sticking or Scorching

It is mainly caused by extended overload operation of the engine, and insufficient cooling, which wears the valve and

deforms the cylinder head, valve seat and valve guide, thus hampering heat dissipation. Moreover, the high temperature

of the engine leads to the oxidation polymerization and decomposition of lubricant and fuel, which forms gelatinous precipi-

tate at the valve head and valve stem, thus eroding the sealing face of valve. Therefore, leakage and scorching occurs. In

order to avoid this, it is necessary to prevent the engine from extended overload operation. It is also required to clean the

carbon deposit on the valve in the course of servicing.

Section 5 Common Troubleshooting of Valve train

93

Chapter 7 Fuel Supply System

1. Mixture quality not to be influenced by air density

This system atomizes gasoline by using an injector based on pressure atomization, which atomizes fuel mainly by means

of the pressure difference between its interior and exterior.When injection happens at fuel inlet bypath, the high tempera-

ture here can be helpful to atomize fuel. So, mixture quality will not be influenced by air density

2. The influence of air density on air-fuel ratio

Because the injector has no venturi, its injection rate is not determined by vacuum degree within venturi. So it is unlike this

system that the air-fuel ratio of the mixture is inversely proportional to the square root of air density, which exists in carbure-

tor. This feature enables it to provide more accurate correction to the influence of air density on air-fuel ratio than carbure-

tor.

3. Mixture well distributed into multiple cylinders when multiport injection applied

For multiport injection, fuel either enters into cylinders or arrives at inlets. So airflows through intake manifolds contain no

fuel and no fuel film adheres to intake manifold wall. This eliminates the problem of bad mixture distribution into multiple

cylinders when carburetor applied.

4. No additional fuel consumption or deteriorated emission caused by load variation when
multiport injection applied

When multiport injection applied, it is pure air that flows through intake manifold. Therefore there will not be additional fuel

entering from fuel film on cylinder wall into the airflow when the pressure therein drops because the throttle is adjusted to

decrease its flow rate.

5. Improved performance under transition working conditions when multiport injection
applied

Multiport injection eliminates the interference from fuel films on intake manifold walls with control of air-fuel ratio, so the

performance under transition working conditions will be improved.

6. Increased volume efficiency

Firstly, gasoline injection eliminates carburetor and venturi, therefore removing the bottleneck of the inlet passage.

Secondly, the absence of fuel film on intake manifolds eliminates the need to heat the intake pipe with exhausted gas, and

therefore intake and exhaust manifolds can be placed respectively on both sides of the engine to form the so-called "Trans-

verse flow scavenging", improving the charge exchange. As a result, the two points leads to increased volume efficiency

and decreased tendency toward knocking.

7. No risk of mixture generation system freezing up

With a high temperature, the injector for multiport injection system cannot freeze up.

8. Operation of gasoline injection system not to be influenced by the engine placement

For gasoline injection system, its operation will not be influenced by the engine placement because the former has nothing

to do with its gravity.

Section 1 Makeup and Features of Fuel Supply

System for Electronic Fuel Injection Engine

I. Excellent Features of Fuel Supply System

for Electronic Fuel Injection Engine

As a control mode, fuel supply system for electronic fuel injection engine is used to electronically control gasoline engine.

It has a lot of excellent features compare with carburetor engine lacks.

94

In engine fuel system, the core of electronic control lies in the electronic control of fuel rate quantity, that is in fact,
electronic control of the excessive air coefficient?.Because intake air amount of gasoline engine is determined through
throttle control by the driver, the fuel rate quantity can be determined through determination of?.
Fuel supply system is composed of the following parts: fuel tank, fuel pump, fuel filter, pressure regulator, fuel injector,
gasoline vapor absorption device etc.
ECU controls fuel feed according to actual engine working condition. Fuel goes through filter to pressure regulator, which
will then keep the fuel pressure within injector constant. Electronic fuel pump immersed in fuel tank continuously supplies
fuel into fuel pipe, and redundant fuel flows through fuel return pipe back into fuel tank.

Engines based on closed-loop control shall use unleaded gasoline.

1. System makeup (See Fig. 208)

2. Fuel pump

II. Structural Characteristics of Piston, Piston Pins and Piston Rings

9. Convenient to cut off fuel supply

Measurement of fuel quantity does not depend on vacuum degree within venturi, so it is still possible to cut off fuel supply
even if the engine is running during intake stroke. This provides convenience for cutting off fuel supply in the event of
overspeed and employing the engine to brake down a long slope.

10. Reduced temperature inside cylinder

Because fuel enters directly into cylinder or arrives at inlet (in this case injection time will overlap the inlet open time), some
fuel will absorb heat and be vaporized, resulting in reduced temperature within cylinder. This can not only increase volume
efficiency thereby enhancing torque and power, but also decrease tendency toward knocking. The latter enables it feasible
to increase ignition advance angle or raise compression ratio by from 0.5 to 1.5 when keeping fuel octane number constant,
thus lowering fuel consumption, or lower requirment for octane number and boiling range for the used fuel when keeping
compression ratio unchanged.

11. Accurate measurement of fuel rate

Carburetor shall carry out quantitative control of fuel rate in addition to various processing functions including atomization,
vaporization, diffusion, and mixing. Its control accuracy is difficult to guarantee. In gasoline injection system, fuel pump and
injector carry out fuel delivery while ECU dynamically controls fuel rate quantity, thus enabling higher control accuracy. For
example, determination of fuel rate quantity in gasoline injection system can take into consideration instant coolant
temperature, inlet temperature and pressure, etc., which cannot be realized by carburetor.

12. Reduced fuel consumption and extended work life

Multiport injection system can realize instant control of mixture according to particular driving conditions and circum­stances.
At the same power level, reduced fuel consumption means lighter heat load, which is helpful for extending work life of such
parts as valve, valve seat ring , cylinder head, and piston.

13. Large speed range for stable running

Gasoline injection engine can work stably within the entire speed range with full load imposed on it, where the ratio of the
highest speed to the lowest speed can reach 10:1 to 12:1. This is because gasoline injection system can accurately control
the air-fuel ratio at any speed, while carburetor is incapable of doing so.

14. Shortened engine height

Elimination of carburetor enables lowered air filter, which will shorten the total engine height so as to make it more conve­nient to arrange the engine in car.
Compared to carburetor, gasoline injection system has the following defects: complicated, costly, difficult to service, and
demanding higher fuel cleanliness and control of gel content in fuel. No or bad control of gel content in fuel will easily lead
to clog of the injector, causing carbon deposit to occur on the back of intake valve. Especially for domestic gasoline based
on the catalyzed cracking process where there is always more than 3% alkene content, some cleanser shall be used.
However, excessive cleanser may lead to deposits occurring within the combustion chamber.

95

Electronic fuel pump, immersed in fuel tank levelly, is fed electricity to through fuel pump relay by battery. This relay’s

switch-on/off is controlled by ECU. When the key in ignition switch is turned to the "Ignition" position, the electronic fuel

pump may not be always powered on. When the key is turned to the "Start" position, ECU will switch on the fuel pump relay,

and the electronic fuel pump will immediately start to continuously supply fuel. When the key is turned from the "Start"

position to the "Ignition" position, it will continue its running. At the moment, it is not the same as the previous case that the

key is placed to the "Ignition" position before its start. This is because ECU can make the fuel pump relay switch on only if

the engine is running. Once the engine stops, the fuel pump will immediately stop its fuel supply.

Electronic fuel pump is made up of pump, electric motor and pump cover (See Fig. 209).

Electric motor consists of a permanent magnet and an armature. On pump cover there are electric contact, connector for

outlet pipe and check valve. Check valve is used to keep some residual pressure within the fuel system after the electric

fuel pump stops running so that it restarts. Without check valve, the positive-pressure fuel will flow back into the fuel pump

and fuel tank resulting in system decompression, so the fuel within the fuel system will be easily vaporized due to high

temperature to produce vapor bubbles and then cause vapor lock. This is a structural fault that is necessarily avoided within

fuel system.

In the fuel pump case, both pump and electric motor are always surrounded by fuel therein. This can satisfy lubrication

requirements of parts and heat emission requirements of electric motor, along with improvement of electric motor

efficiency. In addition, no complex sealing device is required between pump and electric motor.

Fig. 208 Fuel supply system based on multiport injection

1. Fuel tank 2. Electronic fuel pump 3. Fuel filter 4. Fuel deliver pipe (fuel rail) 5. Fuel injector 6. Fuel-pressure regulator

Negative pressure in ntake pipe

96