SUPPORTED BY HUSTLER TURF EQUIPMENT AND EXCEL INDUSTRIES, INC.
FOREWORD
This workshop Manual includes repair and adjustment procedures required for the diesel engine models S7 73L, N843,
and N843L.
When servicing to keep the engine in the best condition, you will find this Manual very useful as a guidebook.
This Workshop Manual was prepared in Jul. 2008. Specifications contained in this Manual are subject to change without
notice for subsequent engineering changes.
This safety alert symbol is used to call attention to a
message intended to provide a reasonable degree of
PERSONAL SAFETY for operators and other persons
during the normal operation and servicing of this
equipment.
BEFORE BEGINNING SERVICE OR REPAIR
1. Read and understand all instructions and safety
warnings in this manual and on any decals on the
equipment.
2. Make sure engine and work area are clean.
3. Place engine or machine on stable, level work
area and/or use an approved engine stand.
4. Stop engine and remove ignition key.
5. Allow engine to cool before preforming service.
6. Disconnect negative (-) battery cable before preforming service or repair.
DANGER—denotes immediate hazards which WILL
result in severe personal injury or death.
WARNING—denotes a hazard or unsafe practice which
COULD result in severe personal injury or death.
▲ Provide adequate ventilation when charging
batteries.
▲ Do not smoke near battery.
▲ Never check fuel level with an open flame.
▲ Never use an open flame to look for leaks
anywhere on the equipment.
▲ Never use an open flame as light anywhe re on or
around the equipment.
▲ When preparing engine for storage, remember
that inhibitor is volatile and therefore dangerous.
Seal and tape openings after adding the inhibitor.
Keep container tightly closed when not in use.
▲ Inspect electrical wiring for worn or frayed
insulation. Install new wiring if wires are damaged.
PREPARE FOR EMERGENCIES
Be prepared if a fire starts.
▲
▲ Keep a first aid kit and fire extinguishers available.
▲ Keep emergency numbers for doctor, ambulance
service, hospital, and fire department near the
telephone.
ENGINE STARTING SAFETY
▲ Do not start engine by shorting across starter
terminals.
NOTE:—emphasizes general information worthy of
special attention.
All operators and mechanics should read this manual, and
be instructed about safe operating and maintenance
procedures. If the operators or mechanics cannot read
and understand English, it is the owner’s responsibility to
explain this material to them.
To reduce the potential for injury, comply with these safety
instructions and always pay attention to the safety alert
symbol, which means DANGER or WARNING—“personal
safety instructions.” Failure to comply with the instructions
may result in personal injury or death.
▲
AVOID FIRE HAZARDS
Be prepared if an accident or fire should occur.
▲
Know where the first aid kit and the fire
extinguishers are located and how to use them.
▲ Unauthorized modifications to the engine may
impair the function and/or safety and affect engine
life.
PREVENT BATTERY EXPLOSIONS
109823 2/091-1
▲
Battery gas can explode. Keep sparks and flames
away from batteries. Use a flashlight to check
battery electrolyte level.
▲ Never check battery charge by placing a metal
object across the posts. Use a voltmeter or
hydrometer.
▲ Always remove grounded (-) battery cable first
and replace it last.
leak under pressure, use a piec e of cardboard or
wood—never use your hands. Relieve all
pressure in the system before disconnecting or
working on hydraulic lines. To relieve pressure,
lower all attachments and shut off engine.
AVOID ACID BURNS
Sulfuric acid in battery electrolyte is poisonous. It
▲
is strong enough to burn skin, eat holes in clothing
and cause blindness if splashed in eyes.
Avoid the hazard by:
1. Filling batteries in a well-ventilated area.
2. Wearing eye protection and rubber gloves.
3. Avoiding breathing fumes when electrolyte is
added.
4. Avoiding spilling or dripped electrolyte.
If you spill acid on yourself:
1. Flush your skin with water.
2. Apply baking soda or lime to help neutralize the
acid.
3. Flush your eyes with water for 10-15 minutes. Get
medical attention immediately.
If acid is swallowed:
1. Drink large amounts of water or milk.
2. Then drink milk of magnesia, beaten eggs or vegetable oil.
3. Get medical attention immediately.
AVOID HIGH-PRESSURE FLUIDS
▲ Escaping fluid (fuel or hydraulic oil) under
pressure can penetrate skin causing serious
injury . Hydraulic oil may cause infection in a minor
cut or opening in the skin. If exposed to hydraulic
fluid, see a doctor at once.
UNDERSTAND CORRECT SERVICE
Be sure you understand a service procedure
▲
before you work on the machine.
▲ Unauthorized modifications to the machine may
impair the function and/or safety and affect
machine life.
▲ If it is necessary to make checks with the engine
running, always use two people - with the
operator at the controls, able to see the person
doing the checking. Use extra safety precautio ns.
▲ Use caution when running engines to avoid
moving and hot parts.
▲ Use the correct tool for the work. Do not use
makeshift tools or substitute parts.
GENERAL MAINTENANCE PRECAUTIONS
Do not perform work or service while under the
▲
influence of alcohol, medication, or other
substances, or when fatigued.
▲ Never run the engine in an enclos ed area unless
exhaust is vented to the outside. Exhaust gases
contain carbon monoxide which is odorless and
deadly poison.
▲ Before applying pressure to fuel or hydraulic
system, make sure all connections are tight and
all hoses and lines are in good condition. To find a
▲ Never remove radiator cap while the engine is
running. Allow engine to cool and remove cap
slowly to relieve pressure.
▲ Never attempt to make any adjust ment s or rep a irs
to the tractor drive system, mower deck or any
1-2109823 2/09
attachment while the tractor engine is ru nning or
deck clutch is engaged.
▲ Repairs or maintenance requiring engine power
should be performed by trained personnel only.
▲ Never work under the machine or attachment
unless it is safely supported with stands, blocks or
a hoist.
▲ Always transport machine in a safe manner.
FUEL HANDLING
Fuel is extremely flammable and explosive under
▲
certain conditions Do not smoke while you fill the
fuel tank, service fuel system or handle highly
flammable material.
▲ Do not remove fuel cap or add fuel t o tank when
engine is hot or running. Allow engine to cool for
several minutes.
▲ Do not use open pans of gasoline or diesel fuel
for cleaning parts. Use good commercial,
nonflammable solvents.
▲ Never refuel tractor while engine is running; never
refuel near an open flame or near devices which
can create a spark. Refuel outdoors preferably or
in well ventilated areas.
▲ Immediately clean up any spilled fuel.
▲ dispose of all fluids properly, and in an
environmently correct maner.
WEAR PROTECTIVE CLOTHING
▲
Wear fairly tight fitting clothing and safety
equipment.
▲ Always wear adequate eye protection when
servicing the hydraulic system and battery, or
when grinding mower blades and removing
accumulated debris.
▲ Prolonged exposure to loud noise can cause
impairment or loss of hearing. Always wear
adequate ear protection, such as earplugs, when
operating this equipment as prolonged exposure
to uncomfortable or loud noises can cause
impairment or loss of hearing. Do not wear radios
or music headphones while operating the
machinery. Safe operation requires your full
attention.
109823 2/091-3
1-4109823 2/09
SECTION 2: GENERAL
General Notes Before Service
1. Clean the exterior of the engine, drain oil, fuel and cooling water as necessary before disassembly.
2. Keep the service shop clean, free from dust, and with adequate lighting.
3. Remove oil and grease from disassembled parts, and place them in groups on a clean t abl e.
4. Be safety conscience; check equipment, tools and wear appropriate clothing.
5. Measurements are in the following format:
Type of measurementUnits
Lengthin(mm)
Torquelbf•ft(Nm){kgfm}
Weightoz(g)
Temperature°F(°C)
Pressure
Fundamental Instructions On Service
1. Keep the engine clean, disassemble only those components that need to be disassembled.
The engine is built to close tolerances and clearances.
2. Retain replaced parts for the customer.
3. Always use machine model, serial number, part number and parts name when ordering service parts.
4. Prelube all moving parts during reassembly.
5. Tighten bolts and nuts to specified torque with proper tools, unless otherwise instructed.
Note: Remove the bolts and plate before pulling the camshaft assembly.
27Front plate•Gasket
109823 2/092-8
28
29
30
31
33
32
33
IndexDescription
28Oil pan•Gasket•Suction filter•Suction pipe
29Fly wheel
30Rear plate or Flywheel cover
31Oil seal
32Piston and connecting rod assembly
NOTE:
1. Before extracting piston, remove the carbon deposit from the top of the
cylinder.
2. Keep pistons, connecting rods, caps and bearings grouped by cylinder
number and reassemble to their original locations.
33Crank shaft and bearing holder assembly
Note: Remove the bolts for bearing holders, and remove the crankshaft and bearing
holder assembly as an assembly.
109823 2/092-9
2-10109823 2/09
SECTION 3: DISASSEMBLY AND INSPECTION OF ENGINE
Fig. 3-1
1. Screw
2. Rocker arm shaft
3. Rocker arm
4. Spring
5. Shim
3
5
1
2
4
Fig. 3-2
Fig. 3-3
Clearance
Caution: before starting disassembly
1. Check the cylinder block and cylinder head for wear, leakage or damage.
2. Clean oil passages with compressed air and check for clogging.
3. Thoroughly clean parts to remove dust, contaminated oil, carbon, and other foreign material.
4. Remove carbon deposits on the piston, cylinder head, valves, etc. being careful not to damage parts. (Especially for aluminum alloy parts.)
5. Valves, pistons, connecting rods, bearings and other parts, should be marked indicating
cylinder number and reassembled to the original cylinder location.
Rocker arm assembly
Disassembly
1. Screw in an M8 bolt at the front en d of the rocker arm
shaft and extract the rocker arm shaft.
2. Take out the spring, shim and rocker arm from the
rocker arm bracket.
Inspection and service
1. Using a micrometer, check outside diameter of the
rocker arm shaft. If the shaft is worn beyond the
service limit, replace the part.
Wear of rocker arm shaft ø in(mm)
Standard assembling valueService limit
0.4587-0.4594(11.65-11.67)Less than 0.4555(11.57)
2. Measure the inside diameter of the rocker arm.
Check the clearance between the rocker arm and
rocker arm shaft. If the clearance is beyond the
service limit, replace the part.
Clearance between rocker arm and rocker arm shaft
Standard assembling valueService limit
0.0013-0.0027(0.032–0.068)More than .008(0.2)
109823 2/093-1
in(mm)
3. Check the valve cap-contact surface for uneven
Fig. 3-4
1. Valve guide seal
2. Spring
3. Retainer
4. Valve
5. Valve cotter
1
2
5
3
4
Fig. 3-5
Fig. 3-6
Fig. 3-7
III III
Stem End
Head End
Thickness
wear and streaks. If wear is insignificant, grind flat
with oilstone or grinder, otherwise, re place.
Cylinder head assembly
Disassembly
1. Using a valve spring compressor, compress the
valve spring to remove the valve cotter, retainer,
spring and valve.
2. Remove the valve guide seal.
Inspection and service
1. Check for distortion of cylinder head bottom surface
by using a straight edge. Using Fig. 3-5 as a guide,
and a feeler gage, check for distortion at the six
positions—A through F. If distortion exceeds the
repair value, correct using a surface grinder.
Distortion at cylinder head bottom surface in(mm)
Standard assembling valueRepair value
Less than 0.0020(0.05)More than 0.0047(0.12)
2. Valve guide and valve stem
a. Check the head and stem of each valve and
replace if burned, worn, or deformation is
excessive.
b. Measure the out side diameter at positions I, II, and
III on the valve stem with a micrometer and
replace if less than the service limit.
Wear of valve stem ø in(mm)
Intake valveExhaust valve
Standard
assembling
value
0.274-0.2744
(6.955–6.97)
c. Replace a valve if its head thickness is less than
service limit.
Service limitStandard
assembling
value
Less than
0.2712(6.89)
0.273-0.274
(6.94–6.955)
Service limit
Less than
0.269(6.84)
Valve head thickness in(mm)
Standard assembling valueService limit
0.0305-0.0423(0.775–1.075)Less than 0.0197(0.5)
3-2109823 2/09
d. Replace the valve if the clearance between the
Fig. 3-8
Clearance
Fig. 3-9
150°
90°
30°
Contact
Width
Fig. 3-10
Fig. 3-11
Recess
Valve
Lapper
stem and guide exceeds the service limit.
Clearance between valve stem and valve guide in(mm)
Intake valveExhaust valve
Standard
assembling
value
0.0012-
0.0024
(0.03–0.06)
Service limitStandard
assembling
value
More than
0.0079(0.2)
0.0016-
0.0030
(0.04-0.075)
Service limit
More than
0.0100
(0.25)
3. Valve seat
a. Since the valve seat is corrected according to the
valve guide, be sure to check the valve guide for
wear condition first before correcting the seat.
Valve seat contact width in(mm)
Standard assembling valueRepair value
In0.059-0.083
(1.50-2.10)
Exhaust0.063-0.071
(1.59-1.80)
More than
0.098(2.5)
More than
0.098(2.5)
b. Correct the seat to the standard assembling values
of the contact width and recess using seat cutters
of 15°, 45° and 75°.
c. When the seat recess exceeds the service limit,
replace the cylinder head.
Valve seat recess in(mm)
Standard assembling valueService limit
In,Ex0.0335-0.0453
(0.85–1.15)
More than
0.0709(1.8)
d. Coat the valve seat surface with compound and
lap the contact surface turning the valve.
e. Check that the valve contact surface is within the
standard value and the contact position is even.
f. When the cylinder head is replaced with a new
head, adjust the seat contact width and seat
recess to the specified values with a seat cutter
before lapping.
109823 2/093-3
4. Valve spring
Fig. 3-12
Fig. 3-13
Squareness
Free Length
Replace with long block assembly
AB
Front
1
Ring Sliding Range
a. Check the valve spring visually for damage.
b. Measure the squareness of the spring using a
square on a surface plate and replace if the
service limit is exceeded.
c. Check the free length and spring force with a
spring tester and replace if the service limit is
exceeded.
Standard
Service limit
assembling
value
Squareness in(mm)0.047(1.2)More than
0.079(2)
Free length in(mm)1.38(35)Less than
1.3(33.5)
Spring force (when
compressed to
1.20(30.4) in(mm))
17.9 lb
(79.8
f
N){8.1 kgfp}
Less than
15.4 lb
f
N){7 kgf}
(68.6
Reassembly
Reassemble components in the reverse order of
disassembly. When assembling the valve spring, retainer
and cotter, be especially careful not to damage the valve
guide seal. Tighten the glow plu g to the proper to rque—5.6-
10.5 lb
•ft(8-15 Nm) {0.8~1.5 kgf•m}.
f
Cylinder block
Inspection and service
1. Check for cracks, damage and distortion on the top
of the block in the same way as the cylinder head.
2. Measurement of cylinder bore
a. There should be no scratches, rust, corrosion, etc.
on the cylinder bore when checked visually.
b. Measure the cylinder bore at the top, center and
bottom respectively in the crankshaft directio n (A)
and the direction at right angle to it (B). If the
repair value is exceeded, replace engine with long
block.
Distortion on cylinder block top surface in(mm)
Standard assembling valueRepair value
Less than 0.0020(0.05)More than 0.0047(0.12)
Cylinder bore dia. ø in(mm)
3.0315-3.0322
More than 3.0394(77.2)
(77-77.019)
3-4109823 2/09
Piston and piston ring
Fig. 3-14
Fig. 3-15
Snap
Ring
Piston
Pin
1
1
Fig. 3-16
Disassembly
1. Remove the piston ring using a piston ring tool.
2. Remove the snap ring and extract the piston pin.
Inspection
1. Piston
a. Check the piston for cracks, streaking and burnout
on the outside surface and replace if excessive.
b. Measure the longer diameter at 0.39in.(10 mm)
above the lower end of th e piston skirt and bore of
the cylinder in the thrust direction, calculate the
clearance, and replace if the repair value is
exceeded.
Piston skirt bottom longer dia .ø in(mm)
Standard assembling valueService limit
3.0288-3.0298
(76.9325-76.9575)
Clearance between cylinder and piston in(mm)
Standard assembling valueService limit
0.0023-0.0034
(0.0575–0.0865)
Less than
3.0197(76.7)
More than
0.0098(0.25)
c. Measure the piston pin hole diameter and piston
pin outside diameter and replace if the clearance
exceeds the service limit.
Clearance between piston pin hole and piston pin
in(mm)
Standard assembling valueService limit
-0.0000~+0.0003
(-0.000~+0.008)
More than
0.0008(0.02)
109823 2/093-5
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