Mitsubishi 4DQ5 Repair Manual

INDEX
GENERAL
MAJOR DATA AND SPECIFICATIONS	5
DISASSEMBLY	8
INSPECTION AND REPAIR ..........................................	16
REASSEMBLY	37
LUBRICATING SYSTEM	49
COOLING SYSTEM	52
FUEL SYSTEM	56
ELECTRICAL SYSTEM ..............................................	71
BENCH TEST	87
MAINTENANCE STANDARDS	89
SEALANT APPLICATION DATA	102
TIGHTENING TORQUE .............................................	103
SPECIAL SERVICE TOOLS	105
TROUBLESHOOTING CHART	110

GENERAL

1. Major component parts

1-1 Left-hand side view

402500

1-Water pump	10-Fuel injection nozzle	19-Cran kcase
2-Fan	11-0il filler cap	20-Flywheel housing
3-Fan belt	12-Fuel injection pipe	21-0il pan
4-Fuel injection pump	13.Rocker cover	22-Drain plug
5-Fuel feed pump	14-lntake manifold	23-Control rack stopper
6-0il pipe	15-Fuel leak-off pipe	24-Governor
7-Fuel inlet connector	16-Cylinder head	25-Starter
8-Fuel feed pipe	17-Adjusting lever
9-Fuel filter	18-Hanger

- 1 -

1-2 Right-hand side view

402501

l-Cylinder head	9-0il filler cap	l7-Alternator bracket
2-Crankcase	10-Exhaust manifold	18-Timing gear case
3-1 ndicator switch	ll-Elbow	19-0il level gauge
4-Flywheel housing	l2-Screw plug	20	-0il pipe
5-Rocker cover	13-Water pump	21	-0il bypass alarm switch
6-0il filter	14-Fan	22	-0il pan
7-Breather	l5-Fan belt	23-0il pipe
8-0il filler	16-Alternator

- 2 -

1-3 Longitudinal sectional view

402502

1-Rocker cover	10-Connecting rod	19-Tappet
2-Thermostat case	11-Cran kshaft pu lIey	20-Camshaft
3-Thermostat	12-Crankshaft gear	21-Crankshaft
4-Exhaust valve	13-Timing gear case	22-Flywheel
5-lntake valve	14-Rocker shaft bracket	23-Flywheel housing
6-Water pump	15-Rocker shaft	24	-0il strainer
7-Piston	16-Valve push rod	25	-0il pan
8-Camshaft gear	17-Cylinder head	26-Drain plug
9-Fan	18-Cran kcase

- 3 -

1-4 Transverse sectional view

402503

1-Exhaust manifold	9-0il strainer	17-Cran kcase
2-Piston	10-Rocker arm	18-Fuel injection pump
3-Valve push rod	11-Rocker cover	19-Fuel feed pump
4-Connecting rod	12-Glow plug	20-Starter
5-Tappet	13-Fuel injection nozzle	21-Cra n kshaft
6-Camshaft	14-lntake manifold	22-0il pan
7-0il level gauge	15-Fuel injection pipe
8-0il pump	16-Cylinder head

-4-

MAJOR DATA AND SPECIFICATIONS

Engine model

40Q5

Type

Water-cooled, 4-stroke, swirl-combustion

chamber type diesel

No. of cylinders-arrangement

4-in line

Bore x stroke

mm (in.)

84 x 94 (3.307 x 3.701)

Piston displacement

cc(cuin.)

2084 (127.l)

Compression ratio

21 : 1

Compression pressure

kg/ cm 2 (p si)

26 (369.7), min (at 150 ~ 200 rpm)

Firing order

1 - 3 - 4 - 2

Direction of rotation

Counterclockwise as viewed from flywheel side

Burns (fuel)

Grade No. 2D diesel fuel (ASTM specification)

Engine oil

Class-CC or better (API service classification)

..a.I

Overall length

717.5 (28-1/4)

Dimensions

Overall width

mm (in.)

562 (22-1/8)

ca

=

Overall height

629.5 (24-3/4)

a.I

(.!)

Weight, dry

kg (lb)

200 (441)

Cylinder sleeves

Dry type made of special cast iron

or integral water-jacket type

No. of piston

Compression rings

2

rings

Oil ring

1 (w/spring expander)

Valve arrangement

Overhead

Intake valves

Open at:

30° BTDC

Valve

Close at:

50° ABDC

timing

Exhaust valves

Open at:

74° BBDC

Close at:

30° ATDC

Valve clearance (both intake and

mm (in.)

0.25 (0.0098)

exhaust valves) (cold)

Starter

Electric

Fuel feed pump

Model

ND-EP/KS22A

Cam lift

mm (in.)

6 (0.24)

Model

PES4A65B

5

Fuel injection

Plunger diam

mm (in.)

6.5 (0.256)

pump

"til

Plunger lead

Right

~

a:i

Cam lift

mm (in.)

8 (0.31)

::I

r-

Model

RUV (for prime power)

Governor

Type

Centrifugal flyweight, all-speed

Fuel injection

Type

Throttle

nozzles

Type of nozzle holders

Bosch CA 17SD

- 5 -

Engine model

4DQ5

Type of nozzle tips

Bosch ND-DNOSD21

~

Fuel injection

Spray hole diam

mm (in.)

1 (0.04)

~

nozzles

Spray angle

0°

~

'1:l

120 +18 (1706 +146)

=

Injection pressure

kg/cm 2

(psi)

""-

Fuel filter

Paper-element type

Type

Trochoid

Speed ratio to crankshaft

1/2

Oil pump

Capacity at oil temp.

50 ± 5°C (122 ± 9°F);

liter (cu in.)/

8.37 (510.8), min/lOOO (pump rpm)

pressure 3 kg/cm 2

min/rpm

e

(42.7 psi)

At duty run

3 -

4 (42.7 -

56.9)

III

Oil pressure

kg/cm

2

(psi)

>'".

At idling

1 -

2 (14.2 -

28.4)

~

'"

.sa

Oil filter

Paper-element type

=

~

..

'"

Type

Piston-valve

.~

3

Relief valve

Valve opening

kg/ cm2

(psi)

3 ± 0.2 (42.7 ± 2.8)

pressure

Refill capacity

Oil pan

liter

6.5 (1. 7)

Oil filter

(U.s. gal)

0.7 (0.18)

Oil bypass

Type

Piston-valve

Valve opening

valve

kg/ cm

2

(psi)

0.8 -

1.2 (11.4 - 17.1)

pressure

Type

Centrifugal type

Water pump

Speed ratio to crankshaft

1.3

Capacity

liter (cu in.)/

105 (6408)/3900 (pump rpm)

min/rpm

Type

Wax

e

Thermostat

Valve opening temperature

76.5 ± 2°C (169.7 ± 3.6°F)

III

Valve lift temperature

90 ± 2°C (194 ± 3.6°p)

>'".

~

'"

Type

Circular-arc pusher type

.Sf

'0

No. of blades

6

0

Fan

U

Outside diameter

mm (in.)

380 (15)

Ratio to crankshaft speed

1.3

Drive belt

Type

Low-edge cog B

No. of belts

1

Refill capacity (engine water jacket)

liter

4.5 (1.2)

(U.S. gal)

-6-

Engine model

4DQ5

Working voltage

volt

12

Polarity

Negative (-) ground

Type

Sheathed

Rated voltage -

volt -

10.5 - 8.3

Glow plugs

current

ampere

Resistance at normal

ohm

1.26

temperature

Model

M002T54172

....

Type

Totally enclosed, drip-proof, pinion-shift type

with overrunning clutch

=

cv

Manufacturer

Mitsubishi-Electric

S

.9-

Starter

i

Voltage-output

volt -

12 - 2

kilowatt

co

.l:t

...

No. of pinion teeth/

11/121

....

No. of ring gear teeth

<:J

~

Model

A001T25070

Type

3-phase AC type

Voltage-output

volt -

12 - 35

ampere

Alternator

Manufacturer

Mitsubishi-Electric

Rated speed

rpm

5000

Working speed

1000 ~ 13500

Speed ratio to crankshaft

1.68

Regulator

Type

IC type built in alternator

Regulated voltage

volt

14.4 ± 0.3

-7 -

DISASSEMBLY

(1)Drain the oil.

(2)Remove the fan belt and alternator as follows:

(a)Loosen bolt (1) securing fan belt adjusting plate and alternator, and remove fan belt (2).

(b)Remove bolts (1) and (3) and remove alternator.

(3)Remove the starter as follows:

(a)Loosen attaching nuts (1).

(b)Remove starter from rear plate.

(4)Remove the fuel filter as follows:

(a)Disconnect fuel feed pipes (1) (2).

(b)Loosen attaching bolts (3) and remove fuel filter

(4).

- 8 -

(5)Remove the injection pipes and injection nozzles as follows:

(a)Loosen connectors (1) and disconnect injection pipes (2).

(b)Remove fuel return pipe (3) by loosening union nut.

(c)Loosen nuts (4) and remove fuel leak-off pipe (5).

(d)Remove nozzle assemblies.

(6) Remove the lube oil pipe from injection pump.

(7)Remove the water pump pulley and crankshaft pulley as follows:

(a)Loosen water pump shaft nut (1) and remove water pump pulley (2).

(b)Loosen crankshaft nut (3) and remove crankshaft pulley (4).

(8)Remove the timing gear case.

(9)Remove the rocker cover.

-9-

(10)Disconnect the water pump bypass hose and oil pipe. To disconnect bypass hose, displace thermostat elbow and water pump clamp.

(I 1) Remove the water pump as follows:

(a)Loosen attaching bolts (1).

(b)Remove water pump assembly (2).

(12)Remove the rocker shaft assembly as follows:

(a)Loosen union nut (1).

(b)Loosen short bolts (2) and long bolts (3).

(c)Remove rocker shaft assembly (4).

(d)Remove oil pipe (5) and "0" rings (2 pcs - to be replaced with new ones).

(e)Remove valve push rods and valve caps.

(f)Remove intake manifold.

(13)Remove the cylinder head assembly as follows:

(a)Loosen cylinder head bolts (1).

(b)Remove cylinder head and gasket.

-10-

(14)Remove the oil pan and oil pump assembly as follows:

(a)Loosen attaching bolts and remove oil pan (1) and gasket.

(b)Loosen attaching bolts and remove oil pump (2) assembly.

(15)Remove the timing gear train as follows:

(a)Loosen idler gear bolt (1).

(b)Remove thrust plate (2) and idler gear (3). (Draw idler gear while twisting it in the direction of its helix.)

(c)Loosen injection pump drive gear nut (4).

(d)Remove injection pump drive gear (5).

(16) Remove the camshaft assembly as follows:

Take out camshaft assembly (1) from crankcase.

[NOTE]

There are tappets in crankcase; this makes it !}ecessary to turn crankcase upside down when removing camshaft assembly.

(17) Remove the front plate and injection pump	•	..	... ~...... .
			@l . ,
assembly as follows:
(a) Loosen attaching bolts (1).
(b) Remove front plate and injection pump
assembly.

-11-

(18) Remove the flywheel and rear plate.

(19)Remove the connecting rod bearing caps and bearings (lower shells) by loosening attaching bolts.

(20) Remove the connecting rods and pistons.

(21)Remove the main bearing caps by loosening attaching bolts.

-12 -

(22) Remove the crankshaft.

(23) Remove the main bearing shells.

(24)Disassemble piston and connecting rod as follows:

(a)Remove compression rings (1) and oil ring (2) by using piston ring tool (A).

(b)Remove oil ring spring.

(c)Remove snap rings (3) by using snap ring tool

(B).

-13-

(d)Remove piston pin (4) by using drift (C).

(e)Remove piston pin bushing and connecting rod bearing (upper).

(25)Disassemble the rocker shaft assembly as follQws:

(a)Remove snap rings on both ends (1).

(b)Remove rocker assembly (2).

(c)Remove rocker bracket (3).

(d)Remove rocker assembly (4).

(e)Remove spring (5).

(26)Disassembly the cylinder head as follows:

(a)Remove nozzle holders.

(b)Remove glow plugs (l).

(c)Loosen bolts (2) securing exhaust and intake manifolds.

(d)Remove exhaust manifold (3).

(e)Loosen thermostat cover bolts and remove thermostat cover (4).

(f)Remove thermostat (5).

-14-

(g)Remove valve cotters (6).

(Depress valve spring by valve lifter.)

(h)Remove retainer (7).

(i)Remove valve spring (8).

G)Take out valve (9).

(k)Remove valve guide by using valve guide remover (A).

lO-Valve guide	A-Valve guide remover
ll-Cy Ii nder head

-15 -

INSPECTION AND REPAIR

Cylinder head

(1)Inspection

Check the gasketed surface of the cylinder head for flatness by using a straightedge and thickness gauge as in the case of checking the crankcase surfaces. This check is to be made with the precombustion chamber jets removed.

Use a surface grinder to reface the cylinder head, as necessary, to the specified flatness.

	Specifications		Unit: mm (in.)
	Item	Standard	Repair limit
	Warpage of gasketed	O.OS,max	0.20
	surface of cylinder
		(0.0020)	(0.0079)
	head

B-

L...::t=---.....--_....~ ...·F

I

o

Checking cylinder head gasketed surface for flatness

(2)Precombustion chamber jet replacement

Do not remove the jets unless they have to be replaced. To remove the jet as when cracks are noted in it, drive it out with a drift pin of about 6 mm

0/4 in.) diameter inserted through glow plug hole, as shown.

Removing precombustion chamber jet

A·lntake port	C·Jet	©
B-Exhaust port

Direction of precombustion chamber jet orifice in installed state

-16 -

Valve guides and valve seats

(1)Check each valve for carboning, burning, wear or other defect on head; also check cap end and stem for cracks. Replace the valve if damaged.

(2)Check each valve guide for wear. Remember, the guide wears down more rapidly at its both ends than at any other parts. Measure the inside diameter of the guide at its ends and at its middle part in two directions. Measure the outside diameter of each valve stem. If the measurement exceeds the repair limit in Table below, replace the valve guide.

(3)Valve face and valve seat

Check valve face and valve seat for wear and contact. If valve face is found excessively worn, reface it by using a valve refacer. To reface the valve, proceed as follows:

,(

,

,

,

) .

~: :~

Wear on valve guide

				Specifications					Unit: mm (in.)
		Item						Standard					Repair
													limit
	Clearance		Intake				0.055 -0.OS5					0.15
						(0.00217 -0.00335)						(0.0059)
	of valve
	stem in		Exhaust			0.070-0.105						0.20
	valve guide					(0.00276-0.00413)						(0.0079)
	Valve guide							18 ± 0.3
	length out-					(0.709 ± 0.012)
	side hole
								S -0.045				-0.10
								-0.060
			Intake			(0315 -0.00177)						(-0.0039)
	Valve stem					.		-0.00236
	diameter							8 -0.060				-0.15
								-0.080
			Exhaust
						(0315 -0.00236)						(-0.0059)
						.		-0.00315

Specifications

Unit: mm (in.)

Item

Nominal

Standard

Repair

Service limit

value

limit

Angle

30°

n

~

Valve

Sinkage

O.S (0.031)

±0.2

1.3

(±O.OOS)

(0.051)

seat

~~~ ~I~am

Width

1.4 (0.055)

±0.14

1.6

C:J~

~

Face i

(±0.005S)

(0.063)

Valve seat~ tValve sinkage 1

Reface up to

Valve margin

1.7 (0.067)

1.2

angle

l

Counterbore

Valve margin

(0.047)

-17 -

Valve refacer

(a)Set a valve refacer to an angle of 45 degrees.

(b)Grind the valve stock to a minimum and, if the margin is less than 1.2 mm (0.047 in.), replace the valve.

Valve seat cutter

Repair an excessively worn valve seat by using a valve seat grinder or valve seat cutter.

(c)When using a valve seat cutter, exercise care so as to apply a uniform pressure to valve seat to prevent uneven cutting. After cutting, reface the seat by rotating the cutter with No. 400 sandpaper put between the cutter and seat.

(d)If valve seat width is overcut, repair it using a 30-degree cutter. If valve seat width exceeds

1.6mm (0.063 in.) due to wear, rep.lace the seat. Also replace the seat when valve sinkage exceeds 1.3 mm (0.051 in.).

Valve seat installation

Chill the valve seat inserts in ether or alcohol containing dry ice. Heat the cylinder head to a temperature of 80°C to 100°C (176°p to 212°p). Press the inserts in the cylinder head by using the insert calking tools (3069102700 for intake valve, 30691-02800 for exhaust valve). Leave the cylinder head and the inserts in the air until shrinkage-expansion fit is obtained between the two. Calk around the inserts with the insert calking tool to machine the seat width.

(NOTE]

The insert calking tool may be used both for pressing and calking the valve seat inserts by reversing the calking ring.

-18 -

'Valve springs

Inspect each spring for cracks, and check it for squareness, free length and as-installed length against these specifications:

Specifications		Unit: mm (in.)
Item	Standard		Repair
			limit
Valve spring free length	48.85		47.6
	(·1.9232)		(1.874)
Valve spring squareness	1.5°, max
Load compress spring to	19 ± 1		15
initial working lenfth
[43 mm (1.69 in.)	(41.9 ± 2.21)		(33.08)
kg(lb)

Checking valve spring

Checking valve spring for squareness

Exhaust manifold

If the flange faces are warped by more than 0.2 mm (0.0079 in.) when checke<;l as shown, grind them smooth and flat. If any flange is found cracked, replace the manifold_

Checking exhaust manifold flange surface for flatness

-19 -

Cylinder sleeves

(1)Using a cylinder gauge, take ID measurements in two directions (parallel and transverse to crankshaft axis) on each cylinder sleeve, at three places indicated below.

If wear reaches the repair limit, rebore the sleeve to the next specifted oversize.

		Specifications	Unit: mm (in.)
	Item	Standard	Repair	Service
			limit	limit
		84 +0.035
		0	+0.20	0.70
	Cylinder sleeve ID (3.307 +g.00138)		(+0.008)	(0.0276)

Out of	0.1
roundness	(0.004),
	max
	0.015
Taper	(0.0006),
	max

I

Taking ID measurements on cylinder sleeves

Crlnkcase gaske,ed surfKe

	oJ,
	0111	(0.43i		1		.:)
	~~'	r 2
				3

'.

Positions for checking sleeve bore diameter

(2)There are three oversizes for cylinder sleeves, namely, +0.25 mm (0.0098 in.), +0.50 mm (0.0197 in.) and +0.75 mm (0.0295 in.). The tolerance to which the sleeves should be refinished by boring is 0 - 0.035 mm (0.0014 in.). When the sleeves are rebored, oversize pistons and piston rings should be used.

(3)An oversize to which any sleeve worn taper and/or out of round is to be rebored should be determined by relying on the most worn part of the sleeve. A cylinder sleeve whose abnormal wear is 0.4 mm (0.0157 in.) should be rebored to 1 mm (0.0394 in.) oversize, for example.

(NOTE]

Removing ridge with ridge reamer

a)All cylinders should be rebored to one and the same oversize.

b)When the sleeves are not worn beyond the repair limit, but the piston rings have to be renewed, correct stepped wear on the top part of the sleeve by using a ridge reamer and, if necessary, refinish the sleeves by honing.

-20 -

(4)When the sleeves are worn beyond the service limit, or when any cylinder bore is found to be defective, the sleeve should be replaced with a new one.

When the inside surfaces of one of more cylinder bores in the crankcase are found to be defective, it is necessary to refinish the bores by boring. In this case, too, the liners should be replaced with new ones. To replace, proceed as follows:

(a) Removal

eFix a boring machine to the crankcase in alignment with the cylinder bore from which a sleeve is to be removed. Aligning should be made at the bottom part of the liner where less abnormal wear has occurred.

•Bore the sleeve until it reaches 0.5 mm (0.0197 in.) in stock thickness.

•Break the sleeve, exercising care not to damage the inside surface of the cylinder bore.

(b) Installation

It Visually check the inside surfaces of the cylinder bores for condition. It is necessary to rebore the bores if they are damaged.

eWhen it is unnecessary to reb ore the cylinder bores, proceed as in steps below.

•Measure. the diameter of cylinder bore and the outside diameter of sleeve. Select oversize sleeve so that the clearance between the sleeve and the bore is 0.08 mm (0.0031 in.) to 0.145 mm (0.0057 in.).

Heat the crankcase to about 300°C (572°F). Press the sleeve into the bores in the crankcase by using a hydraulic press in such a manner to make the top of sleeve protrude by 0.3 to 0.5 mm (0.012 to 0.020 in.) from the crankcase. Then, finish them to be flush with the crankcase.

After pressing the sleeves, rebore and hone them to

th	em	t	a	84 +0.035	(3307 +0.0014. )
				0	mm.	0	tn ..

Pressing sleeve

•When it is necessary to rebore the cylinder bores, press the sleeves into position as in b above, and proceed as follows:

Prepare 0.5 mm (0.0197 in.) oversize cylinder sleeves.

Rebore the cylinder bores so that the clearance between the sleeve and the bore is 0.08 mm

(0.0031 in.) to 0.145 mm (0.0057 in.).

After pressing the sleeves, rebore and hone them to

	th	em	t	a	84 +0.035				(3307 +0.0014.				)
					0			mm.			0	m..
							Specifications					Unit· mm (in )
	Cylinder sleeve									Sleeve
								boring dimension
	Standard						87 -0.010 (3 425 -0.0004)
								-0.045			.	-0.0018
	0.5 -oversize						875-0.010				(3 445 -0.0004)
								. -0.045			.	-0.0018
	When replacing the sleeves, use the sleeves of the
	following part numbers.
							Specifications					Unit: mm (in.)
	Part No.					0.0.					1.0.			Remarks
					87+0 .10					83.5		0
30607-50301						+0.07						-0.2		Standard
					(3 425 +0.0004)					(3.287_0.
													)
					.	+0.0028						0 008
					875+0.10							0
30607-50401					.	+0.07				83.5 -0.2				Oversize
					(3445 +0.0004)							0
										(3.287 -0.008)
					.	+0.0028

-21-

Pistons and piston rings

(1)Pistons

Inspect each piston for any abnormal wear of its sliding surface, for cracks at the crown and for evidence of melting or fusion. Examine the ring grooves for stepped wear and sloped wear. Replace pistons found in bad condition.

(2)Measure the outside diameter of piston in two directions perpendicular to each other. If the diameter exceeds the service limit, replace the piston.

			Specifications					Unit: mm (in.)
	Item					Standard				Service
										limit
	Standard			83.90 (3.3031)
	0.25 (0.0098)			84.15 (3.3130)
Diameter	oversize
										-0.2
(at skirt)	0.50 (0.0197)			84.40			(3.3228)		(-0.008)
	oversize
	0.75 (0.0295)			84.65 (3.3327)
	oversize

-22-

(3)Replacing pistons

Replace the piston with a new one if the measurement exceeds the service limit. Where any pistons have to be replaced, the variance in weight among the pistons must not exceed the limit. It is recommended that cylinder number be stamped on a piston selected to be used in a particular cylinder for convenience.

When the cylinder sleeves are bored to the oversize, pistons and piston rings of the same oversize

should be used. There are three oversizes for pistons and piston rings, namely, +0.25 mm (0.00984 in.), +0.50 mm (0.01969 in.) and 0.75 mm (0.0295 in.). The variance in weight among the pistons per engine should be ±5 grams (±0.18 oz), max.

(4)Piston riD& gaps

Check the ring gap with a thickness gauge by placing the ring in a new cylinder sleeve, and pushing the pistOll true and square in the bore.

Front of engine

t

Pilton _ight

Piston weight marking

Piston ring

Gap

Checking piston ring gap

	Specifications			Unit: mm (in.)
Item				Standard	Service
					limit
Piston ring gap				0.30 ~0.50	1.5
		(0.0118 ~ 0.0197)			(0.059)

(5) Piston ring grooves

Insert the compreuion and oil rings of known thicknesses into the grooves, and measure the side clearance with a straightedge and thickness gauge@.

				Measuring piston ring groove
			Specifications
				Unit· mm (in )
		Item		Standard	Repair
					limit
Fit in ring		No.1 compression		0.050 ~ 0.085	0.20
		ring		(0.00197 ~ 0.00335	(0.0079)
grooves
		No.2 compression ring		0.025 ~ 0.060	0.15
		Oil ring		(0.00098 ~ 0.00236)	(0.0059)

-23 -

(6)Replacing piston riDp

If the rings are replaced, the gap width will exceed the standard value, but this is not a matter of concern, provided that the service limit is not exceeded.

(7)Piston pin bosses

Check the piston pin bosses by referring to the topic, Piston pins, piston pin bosses and piston pin bushings, which follows.

Piston pins, piston pin bosses and piston pin bushings

(1)Check the pin clearance in the pin boss of the piston by computing the difference between the two diameter readings, one taken on the pin and the other in the boss. If the computed difference (clearance) exceeds the repair limit, replace the piston pin with a new one.

	Specifications		Unit: mm (in)
Item		Standard		Repair
				limit
Piston pin		0
		25 -0.006
diameter		(0.984_8.00024 )

(2)('heck the clearance of the pin in the bushing fitted to the small end of the connecting rod by computing the difference between the two dia· meter readings. If the computed difference (clearance) exceeds the repair limit, replace the pin or the bushing whichever is badly worn.

	Specifications
				Unit· mm (in		)
	Item			Standard	Repair
					limit
	Piston pin boss		25 -8.006
	ID		(0.984 -8.00024)
	Piston pin clear-		0-0.016		0.05
	ance in piston
			(0 - 0.00063)		(0.0020)
	pin boss
	Piston pin		25 +0.020
			·+0.045
	bushingID		+0.00079
			(0.984 +0.00177 )
	Piston pin clearance		0.020 - 0.051		0.08
			(0.00079 -
	in piston pin bushing				(0.0031)
			0.00201)

Miking piston pin bushing and piston pin

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Connecting rod alignment and bearings

(l)Check the connecting rod for evidence of cracks, especially cracks in the fillets of its small and big ends. Replace the rod if any cral:k is noted in the fillets.

(2)Mount each connecting rod in the connecting rod aligner and check for bend and twist as shown

below. In a twisted connecting rod, the bearing is not trued to the small end bushing. Such a rod must be corrected with the use of a press.

(3)If the connecting rod aligner is not available, the rod may be checked as follows:

(a)To check the rod for bend, measure "c" and

"2" as shown in the figur~ "a." If the measurement at "c" is larger than 0.05 mm per 100 mm

(0.00197 in. per 3.937 in.) of" 2," straighten the rod with the use of a press.

(b)To check the rod for twist, measure "c" as shown in the figure "b." If the measurement at "C" is larger than 0.05 mm per 100 mm (0.00197 in. per 3.937 in.) of "2," correct the rod.

f <0.05 t 100

a. Checking the connect·	b. Checking the connect·
ing rod for bend	ing rod for twist

Checking connecting rod

Checking connecting rod for bend

Checking connecting rod for twist

-25 -

(4) To	~he.:k the	rod with a piston, pla~e the rod on
the	surfa~e	plate as shown below, insert a
round bar of the ~rankpin diameter into and
through its big end bore, and take measurement
at "A" and "B." The differen.:e between the two
measurements		tel1s the straighteness of the rod.

When one or more, or all connecting rods are to be repla~ed, sele~t new rods so that the variance in weight among the rods is within the value given in the spedfication.

Specification

Unit: gram (oz)

Variance in weight among connecting rods

A

B

//

/

Checking connecting rod on surface plate

(5)Check the connecting rod end playas follows:

Check each connecting rod for end play in the manner illustrated, with the cap bolts tightened to 5.5 kg-m (39.8 lb-ft). Use a thickness gauge to measure the end play (which is the clearance between big end and crank arm). If the clearance measured exceeds the service limit, replace the connecting rod or bearing.

	Specifications	Unit: mm (in.)
Item	Standard		Service
			limit
				Checking end play of connecting rod
Connecting rod	0.15 -- 0.35		0.50
end play	(0.0059"" 0.0138)		(0.0197)

(6)Check the bearings as follows:

(a)Inspect each bearing for evidence of wiping or fatigue failure, for scratches by dirt particles imbedded in and for improper seating on the bore. Determine whether the bearing should be re-used or replaced on the basis of fmdings.

(b)Check the radial clearance between crankpin and bearing; if the repair limit speCified below is exceeded by the checked clearance, replace the bearing. Where the crankpin is to be ground to the next undersize, use a replacement bearing of that undersize.

The two bearing undersizes are 0.25 mm (0.00984 in.) and 0.50 mm (0.01969 in.).

-26-