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direction, i.e., the big end is eccentric to connecting rod body. Connecting rod can fit the crankshaft properly only

under following conditions: arrowhead mark on the top surface of piston points front; the marks (protuberated) on

connecting rods for cylinders No.1 and 3 face forward; and that for cylinders No. 2 and 4 face rearward. So, when

to reassemble the piston connecting rods, these for cylinders No. 1, 3 and for No. 2, 4 should be sorted and

reassembled respectively. The weight difference among groups should not be more than 5 g.

Figure 8-8 Upper/Lower Main Bearing Shell of Crankshaft

1-Upper main bearing shell; 2-Oil hole; 3-Locating protruded lip; 4-Lower main bearing shell

Before the piston connecting rod is installed into the cylinder liner, apply the clean oil on the outer surface of

piston, connecting rod small end and bearing shell surface. The openings of the first and second piston rings

should mutually stagger 180°, and avoid pointing to the direction of piston pin. The oil ring and the second ring

should stagger 90° (see Figure 8-5).

When the piston connecting rod is installed into the block, the piston head guide groove should face the

tappet side (injection pump side). After tightening the connecting rod bolt to the specified torque (55 – 65 N·m)

during assembly, check if the crankshaft rotates smoothly and if there is an axial clearance in the connecting rod

big end.

● Note: Replace the body and cap of the connecting rod in pair at the same time.

8.2.8 Assembly of Upper/Lower Bearing Shell of Crankshaft

The crankshaft journal of turbocharged diesel engine is supported on the block by the main bearing cap. The

upper bearing shell of crankshaft has the oil groove and hole (see Figure 8-8), and the upper and lower bearing

shells are not interchangeable.

When to press to mount the timing gear, the mark “X” on gear should face outward (see Figure 8-9).

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Figure 8-9 Gear Drive Mechanism

1-Injection pump gear, with Mark Y; 2-Idle gear, with marks Y, Y;

3-Camshaft gear, with marks X, X; 4-Crankshaft gear, with mark X

8.2.9 Assembly of Flywheel

The flywheel is installed by 6 bolts to ensure the reliable installation strength. During installation, tighten the

bolts clockwise three times with the tightening torque of 80 – 90 N·m.

Apply oil on bolts thread before mounting flywheel bolts.

8.2.10 Assembly of Timing Drive Mechanism

The turbocharged diesel engine’s gear drive mechanism includes: the injection pump drive gear, camshaft

gear, idle gear, crankshaft gear and other gears, as shown in Figure 8-9.

The open/close timing of the diesel engine’s intake/exhaust valves and fuel supply timing of injection pump

are strickly set in relation to the movement position of crankshaft. The camshaft gear, injection pump gear and

crankshaft gear are correlated via the timing idle gear. The crankshaft gear, camshaft gear, injection pump gear

and idle gear all have their own assembly marks.

A tilted convex rib is forged on the gear chamber cover, and there are the inscribed lines on the crankshaft

pulley (see Figure 8-10), which are used for the adjustment of top dead center.

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Figure 8-10 Crankshaft Pulley

Marks are inscribed on the surface of outer circle of the crankshaft pulley; 0-means the top dead center of piston;

6-means 6º before top dead center (crankshaft angle); 16-means 16º before top dead center (crankshaft angle)

When to mount timing gear drive mechanism, align these marks with each other to ensure the correct port

timing and fuel supply timing. Otherwise there would be some malfunctions happening such as engine fails to

start up, or its power goes down, oil consumption increases, or in worst case, the piston head could bump to valve

to cause damage.

After the installation of timing gear group, check the port timing.

If the complete gear drive mechanism is required to be replaced due to the unclear and invisible marks or

worn-out gear, please get to the professional service shop or the service stations authorized by Foton Motor

Company.

8.2.11 Assembly of Camshaft

The highlights on the assembly of the camshaft assy.:

(1) When pressing in the cam gear and idle gear, the gear marks “X, X” and “Y, Y” should face outwards

(see Figure 8-9).

(2) When to mount tappet into the tappet bore in cylinder block, apply the lubricating oil on them. Installed

tappet should be able to rotate by hand.

(3) After oil pump has been tightened, the camshaft should be able to rotate by hands.

8.2.12 Assembly of Intake / Exhaust Valve

The valve is used to control the open/close of the intake / exhaust passages.

Replace any worn out valve.
● Caution: The valve spring locking plate should be correctly installed into the spring seat, otherwise

locking plate might fall off to cause the valve dropping into the cylinder.

8.2.13 Valve Clearance

The valve clearance means the gap between the back end of valve stem and the rocker arm measured when

valve closes near the top dead center of compression stroke.

Valve clearance should be appropriate. Too large clearance could cause impact among valve, valve seat and

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other components, which will shorten their service life. it may also delay the valve open timing and advance the

valve close timing, thus shorten compression and exhaust time to reduce engine power. While too small valve

clearance will shorten the time to warm up components, valve can’t fully close, that also reduces engine power.

During the combustion, it could lead to the high-temperature gas leakage from the gap, overheaing or even burn

out valves.

During the course of operation, all factors could ficilitate clearnance change including worn-out parts,

loosened adjusting screw, overhauled cylinder head or parts and retightening of cylinder head nuts. Therefore, it is

required to check and adjust the valve clearance regularly.

The intake / exhaust valve (cold state) clearance of a turbocharged diesel engine is 0.35 mm ± 0.05 mm. If it

changes during the practical use, check and adjust it in accordance with the following procedures.

(1) Turn crankshaft till 1

st

cylinder piston reaches TDC of compression stroke, saying pulley TDC mark “0”

aligns the pointer on gear cover, and intake/exhaust valves in 1

st

cylinder are both closed (see Figure 8-10).

Perform adjustment on 1,2,3,5 valves(see Figure 8-11).

Figure 8-11 Adjustment of Valves No. 1, 2, 3 and 5

(2) Insert a feeler into rocker arm and valve (see Figure 8-12), and loosen concerning rocker arm locking nut,

turn adjust screw with a screwdriver till feeler becomes snug. Then retighten the nut

Figure 8-12 Check the Valve Clearance Using a feeler

Front

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(3) After adjustment is done, turn crankshaft 360 degree. At the moment, 4

th

piston is at its TDC of

compression stroke. Perform same adjustments on remaining 4,5,7,8 valves.

8.2.14 Check the Turbocharger before Installation

Remover a new turbochanger’s external packaging to check if its rotor rotates freely. If there are impacting

sound or rotation lagging, find out the reasons and install it only after troubleshooting.

Check and clean the air filter element. Replace paper element in accordance with the technical requirements.

Check and clean compressor intake pipe and engine exhaust pipes. Keep any foreign objects off from

turbocharger.

Check the oil filter and replace contaminated and damaged.filter element

Check and clean turbocharger’s oil supply and return pipes to ensure it is clean without distortion. The shims

for oil supply and return pipes are not allowed to block off the oil supply / return holes in turbocharger.

Check oil and change diry or deteriorated oil.

8.2.15 Installation of Turbocharger

The turbocharger should be secured reliably. The tightening torque of the exhaust pipe nut connecting to the

turbocharger should be 28 – 35 Nm, and the oil inlet / return pipe should be connected reliably. When to install the

oil inlet/return pipe, do not apply the sealant on the joint to avoid the entrance of the sealant into the turbocharger

and thus prevent the parts and components from be damaged.

Secure the double-steel-wire clip used to fix turbocharger’s rubber connection hose, avoid air leakage which

causes the power down.

After a new turbocharger is installed on the diesel engine, refill the clean engine oil through the oil filler

opening, turn the rotor by hand to pre-lubricate the turbocharger.

8.2.16 Check and Adjust the Turbocharger

Adjust the relative angle of turbocharger housing:

(1) Unscrew the bolt securing the compressor casing (or turbine casing), keep oil return opening on the

intermediate casing downward vertically, and turn the compressor casing (or turbine casing).

● Caution: DO NOT fully unscrew the bolt to avoid the impeller contacts with the casing.

The torque of compressor casing bolts should be 5.7 N·m,

The torque of turbine casing bolt should be 11.3 N·m.

(2) If necessary, check the operating condition of the turbocharger rotor. Turn the rotor by hand, a normal

rotor can rotate by itself at least one turn. Dismantle to check faulty turbocharger. Rotor check needs absolute tidy

operating environment to keep foreign object from entering the turbocharger..

Use the special equipment and tools to disassemble and reassemble the turbocharger assembly. As only the

turbocharger manufacturer and service center (station) have these special equipment and tools, user is not

suggested to perform these operations by himself unless it has to.

(3) Disassemble the compressor casing and check for oil leakage. At the same time, clean the inside

chamber of compressor casing and the surface of compressor impeller. Special care should be taken to protect

impeller during cleaning.

8.2.17 Adjust Advance Angle of Fuel Injection Pump (Stationary State)

The optimal fuel supply advance angle of a diesel engine is preset by the manufacturer. The advance angle

of fuel injection pump should be 8º - 12º CA before top dead center (crankshaft angle)of compression stroke. In

winter, the angle can be adjusted up to its upper limit while down to its lower limit in summer.

The improper advance angle will influence engine’s power, fuel consumption and normal operation. Adjust

any improper advance angle as per following methods:

(1) Check the advance angle of fuel injection pump (stationary state)

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Loosen the No 1 cylinder’s high pressure fuel pipe nuts, turn the crankshaft counter-clockwise and stop

turning at the moment fuel drips from the piston in No 1 cylinder. In this case, the scale reading on crankshaft

pulley that aligns with pointer on gear chamber cover is the value of advance angle. The scale readings are 6º, 8º ,

10º, 12º, 14º and 16º respectively.

(2) Adjust advance angle of fuel injection pump (stationary state)

If the advance angle checked above doesn’t conform to the specified value, loosen three nuts on injection

pump, move the injection pump slightly inward or outward. Advance angle decreases as it moves inward while

advance angle increases as it goes outward. When the advance angle of fuel supply reaches its ideal position,

tighten the above mentioned three nuts, and finally, check again whether or not the adjusted advance angle of fuel

supply is proper.

● Caution: It is not allowed to dismantle the parts with lead seal on injection pump. Approach to

professional help. And if necessary, conduct the testing and adjustment on the special test stand.

8.2.18 Check Fuel Injector

The turbocharged diesel engine adopts the S series multi-orifice injectors, Model CKBEL87S069 or ZP22

(see Figure 8-13). It atomizes the fuel and sprays into combustion chamber where fuel mist mixes with the air and

become combustible mixture.

Figure 8-13 Fuel Injector Assembly

1-Injector; 2-O-ring; 3-Copper washer

Malfunction of a fuel injector will lead to uneven engine Rpm and black smoke emitting. In order to find

which injector is faulty, you should set throttle on a position where engine Rpm is most irregular, unscrew high

pressure pipe joint nuts on fuel injection pump top to shut off fuel supply to relevant cylinder. If the engine Rpm

does not change much at a cylinder whose fuel has been cut off while engine emits less smoke, injector in this

cylinder must be faulty and should be removed.

8.2.19 Replace Fuel Injector

● Caution: DO NOT let the contaminated material and dirt enter the fuel system. Before disconnect the

connector, thoroughly rinse the jointing area. Use appropriate goods to cover the connector that has been opened.

(1) Disassemble the fuel return pipe.

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(2) Disassemble the high pressure fuel pipe connecting nuts from the injector and injection pump. Do not

bend the fuel pipe, and if necessary, disassemble the return pipe clamp.

(3) Remove retaining screw, and detach the clip, injector, O-ring, injector washer. Install new O-ring and

injector washer on the new injector.

(4) Mount the new injector, O-ring and injector washer. Put on pipe clamps and retaining screw. Ensure the

injector does not tilt. Evenly and gradually tighten the retaining screws.

● Caution: Tighten high pressure pipe connecting nuts with specified tightening torque. If any leakage

occurs around nut, check whether the fuel pipe is correctly aligned with the inlet of injector. DO NOT over-

tighten the injector connecting nut, otherwise fuel pipe end will be crashed, thus fuel supply is affectd.

(5) Install the high pressure pipe and tighten the connecting nut.

(6) Replace the sealing gasket and install the fuel return pipe, tighten the blots.

(7) Start the diesel engine, and check for fuel and air leakages.

8.2.20 Check the fuel injection quality of the injector

Check injecting quality. Put a fuel injector on test stand to observe its spraying quality. Clean, adjust and

even replace injector in the events of poorly atomization, fuel spills, leakage and strange injecting sound (see

figure 8-14).

A normal injecting quality is identified with following conditions: fine fuel mist; a certain cone angle

(between 4-12°); clear sound of “pop, pop…”; clear and quick fuel shutoff; no dripping or leaking after injecting.

Moisture at injector tip is allowed.

● Caution: Do not go on using an injector which fails to satisfy the technical requirements. Replace it with a

new one

8.2.21 Check the Injection Pressure of the Injector

All injectors in a new diesel engine has been checked and adjusted in the factory, users can directly use it

without readjustment. However, after the diesel engine has operated for a period of time, injector spring elastic

force will change, that makes injector pintle opening pressure changing. In addition, chenk ther pressure after

injector had been removed and cleaned.

Check the injection pressure of injector on a test bench: secure injector on the test bench, disassemble the

fuel pipes, at this momnet pressure gauge indictates “0” . Pump the fuel and observe pressure gauge indication.

Check whether pressure gauge indicates specified value (20 – 21 MPa).

Figure 8-14 Check the Injection Quality of an Injector Using a Test Bench

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8.2.22 Regulation of Injector Opening Pressure

The opening pressure of a injector in turbocharged diesel engine is regulated by increasing and decreasing

the thickness of the pressure regulating shim to injector body. Increase the thickness of shim to raise the opening

pressure; and decrease the shim thickness to reduce the opening pressure.

If it is required to regulate the injection pressure, operator should clean the outside of injector and unscrew

the tightening nuts. Note that the coupling parts, tappet, springs and original washer should not be discarded. Keep

all part and component clean.

8.2.23 Check the Thermostat

Thermostat automatically changes coolant flow in radiator according to engine temperature to maintain

engine in a proper operation temperature. (figure 8-15)

The temperature sensing element of the thermostat is a paraffin-type one. The thermostat is installed in the

thermostat casing at the water outlet on the cylinder head.

Figure 8-15 A Thermostat

Figure 8-16 Thermostat Test

1-Thermometer; 2-Water under Heating; 3-Thermostat

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A bypass valve under thermostat closes when thermostat valve opens, coolant then flows into radiator to

improve cooling. The thermostat valve closes when water temperature is low, and then the bypass valve opens to

cut off the passage from the water jacket to the radiator, and the coolant enters the water pump through the bypass

pipe and then is driven back to the water jacket. In this case, the coolant doesn’t go through the radiator, it

circulates only between the water jacket and water pump. This small circulation could help to warm up diesel

engine quickly. When coolant temperature is high, thermostat valve will fully open, the minor circulating bypass

valve is closed at the same time to let coolant flow into the radiator and conduct the major circulation to improve

heat dissipation.

Thermostat initial opening temperature is 76℃±2℃, full opening temperature is 90℃. Full opening travel

is no less than 8mm.

Test thermostat: remove thermostat, put it into a container with water to warm it up gradually. Observe

temperature with a thermometer. While water temperature is changing, check if valve closes or opens as

requirements (see figure 8-16). Otherwise replace thermostat.

Figure 8-17 Check and adjust water pump belt tension

8.2.24 Adjust Belt Tension

Fan belt tension should be proper. If it is too loose, the belt will slip over the belt pulley. This would decrease

fan speed to affect cooling system performance and speed up belt wear. While too tight belt would facilitate

bearing wear and increase power consumption.Check the belt tension regularly.

Install the belt into alternator and water pump belt pulley groove first, then into the crankshaft pulley

groove. To tighten the fan belt, turn the alternator outward, and tighten the fastening bolts.

Check fan belt tension after a diesel engine has operated up to 100h (vehicle milieage 4,000~ 5,000 km).

Hand press the belt (70 ~80 N ) at the spot between the water pump and alternator pulle. Its deflection should be

preferentially 6~8 mm (see Figure 8-17).

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Chapter 9

Diesel Engine Faults and Troubleshooting

During diesel engine operation, technical state of the parts could deteriorate gradually due to wearing,

distorting and improper maintenance. When some technical indices exceed the limits, the engine is faulty. The

common faults on a diesel engine are: hard start-up, rough operation, lack of power, abnormal sound during

operation, abnormal exhaust gas color, lower oil pressure and higher coolant temperature, etc.

Remove any engine faults whenever they happen. Engine operates with faults would reduce its power and

economy and deteriorate its operating performance. Moreover, it would accelerate parts wear or lead to accidental

damages.

● Notes:
（1）Diagnose an engine according to symptoms and by referring to diesel engine’s construction /operation

theories. Avoid missing a fault or dismantling blindly.

（2）Much complicated diagnosis or fault-removing procedures may need to use instrument or special

equipment, and be performed by technician.

The diesel engine faults and removing procedures in this chapter are for reference only.

9.1 Hard start-up

Symptoms and causes

Removing procedures

Wrong circuit connection or poor

contact

Check if connections are tight and reliable.

Weak battery

Charge battery

Poor contact between start brush

And commuter

Repair or replace brush. Polishing commuter surface with wooden

sandpaper and blow it clean

Stuck or failure starter solenoid

Adjust solenoid and replace if necessary

Electrical

system

Failure pre-heating system

Replace glow plug

Air in fuel system

Check if fuel supply connector is loose. Loosen vent screws on

injection pump and fuel filter, press hand pump till no bubble in

overflowed fuel. Retighten vent screws and hand pump.

Choked fuel pipe

Check if fuel pipe is clear.

Blocked fuel filter

Clean fuel filter or replace element.

Fuel pump failure or inconsistent

supply

Check fuel inlet pipe for air leaking and if screen net is blocked. If

there is no fuel supply after removing faults, check fuel inlet pipe

and fuel pump.

Less injection from injector. No

injection or non atomization

Check injector for its atomizing state, check to see if injector

plunger and oil outlet valve is worn-out or stuck, check and adjust

the injection pressure to specified range.

Fuel

system

No fuel supply from injection

pump

Check and repair.

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Symptoms and causes

Removing procedures

Worn-out piston compression

ring

Replace piston ring. And replace cylinder sleeve as per its wear

situation.

Mechanical

system

Leaked valve

Check valve and valve seat for air sealing. Repair or grind if

necessary.

9.2 Hard start-up at low temperature

Symptoms and causes

Removing procedures

Fuel

In winter or cold area, diesel becomes
turbid and frozen due to selection of
wrong fuel.

Use low-freezing diesel according to local ambient
temperature

Oil

In winter or cold area, selecting
wrong oil. Oil becomes too viscous,
which increase interior friction and
the resistance to start-up.

Use low-viscosity oil according to local temperature of the

diesel engine in order to decrease the starting power.

Battery

Select to use battery whose volume is
less than 100Ah in cold area or in
winter

Select to use low-temperature battery whose volume is
larger than 100Ah according to local temperature

9.3 Insufficient power

Insufficient diesel engine power means engine power does not reach the designed requirements. Engine is

“weak” and tends to stalling under heavy load or climbing a hill. The lack of power usually comes with hard start

up. They are related to each other, cross-reference diagnosing can be made thereupon.

Symptoms and causes

Removing procedures

（1）air in fuel pipe and fuel filter, or
they are blocked.

Bleed the system or replace fuel filter element, flush oil
pipes.

（ 2 ） insufficient fuel supply from
injection pump.

Check, repair or replace plunger sets.

Power and

Rpm do not

increase

after

depressing

gas pedal

Fuel injector atomization is poor or
injecting pressure is low and some fuel
injectors are stuck.

Check fuel injector atomization or adjust injecting
pressure. Check, repair or replace injector parts.

Blocked air filter

Remove dust on air filter element. Replace if necessary.

Bad exhaust

gas color

with higher

temperature

Exhaust pipe has longer connector or
connecting pipes, small turning radius
or to many elbows.

Remove carbon deposit inside the exhaust pipe, re-install
exhaust connecting pipes, use less than 3 elbows with
enough exhausting section.

Fuel supply advance angle and valve
timing are changed.

Check and adjust the static fuel supply advance angle and
valve timing.

Poor

performance

at each gear Valve clearance is changed.

Check and adjust the valve clearance.

Coolant temperature is too high.

Check cooling system, remove water scale; check belt
tension and adjust it if necessary; check thermostat.

Oil temperature is too high.

Check oil volume and add if necessary; if bearing and any
motion parts get hot, find out the cause and remove

Diesel

engine

overheating

Exhaust gas temperature is too high.

Check and correct static fuel supply advance angle and
fuel injector injecting pressure

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Symptoms and causes

Removing procedures

Leakage at contacting face between
cylinder head and block. Cylinder-head
bolt is loose or the cylinder-head gasket
is damaged.

Tighten cylinder head as per specified torques, or replace
cylinder-head gasket.

Leakage at intake/exhaust valves

Disassemble and check intake/exhaust valves, grind
contacting face between valve and valve seat. Replace
parts if necessary.

Valve clearance is not correct.

Adjust valve clearance to standard.

Lack of

power,

performance

deteriorates,

leakage,

black smoke

and

abnormal

slapping.

Leakage at injector hole, or copper
washer is damaged

Remove to check injector. Clean injector hole and replace
damaged parts.

9.4 Abnormal noise during operation

First of all, operator should recognize what a abnormal sound is like: either a knock due to an abnormal

breaking-out or clashing noise due to parts’ abnormal motion. Diagnose to locate sound source according to its

acoustic feature together with parts construction theory.

●Cautions: It is strictly prohibited to keep a diesel engine operating with abnormal noise. Once hearing an

abnormal noise, you should stop vehicle immediately to check and remove the fault to avoid accident.

Symptoms and causes

Removing procedures

Early injecting or fuel injector is stuck, there is clear

metal-beating noise in the cylinder.

Adjust static fuel supply advance angle, and check fuel

injector for injecting.

Excessive clearance between piston pin and connecting

rod small end bushing hole, which makes light and

sharp noise. The noise is clearer during idle running,

and turns sharper when throttle is opened wider

suddenly.

Replace connecting rod small end bushing to make its

clearance reaching the standards

Excessive clearance between piston and cylinder

sleeve, and clashing noise can be heard from engine

outside. The noise gets louder with rising of engine

Rpm.

Replace piston, piston ring. Or replace cylinder sleeve

depending on its wear.

Excessive clearance between connecting rod bearing

and main bearing due to wear. Clashing noise among

engine parts can be heard at crankcase during

operation. And heavy and strong knocking can be heard

when engine Rpm is slowed down suddenly.

Disassemble to check bearing. Replace it if necessary.

And keep specified fitting clearance.

Valve knocks piston. Heavy, even and rhythmical

beating noise can be heard at cylinder head.

Find out knocking cause, check valve timing, and

adjust valve clearance.

Drive gear is worn-out or with excessive clearance.

Abnormal noise comes out from gear chamber. And

knocking noise can be heard at sudden deceleration.

Check driving gear clearance and replace gear if

necessary.

Excessive clearance at intake/exhaust valves. Louder

and rhythmical sound can be heard at cylinder head.

Re-adjust valve clearance.

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9.5 Abnormal exhaust gas color

The color of exhaust gas under normal load is light gray, and deep gray for the most under short heavy load.

Blue, white or black gas indicates faults are occurring. Blue indicates oil burning; white indicates that atomized

diesel have not burnt in cylinder or there is water in the fuel; and black indicates the injected fuel is excessive,

which has not burnt completely.

Symptoms and causes

Removing procedures

Diesel operates under overload.

Reduce diesel engine load to specified range.

Uneven fuel supply among cylinders

Adjust fuel supply to each cylinder from injection

pump.

Incorrect valve clearance, poor valve

sealing (exhaust valve is leaking)

Adjust valve clearance and check sealing cone.

Smaller fuel injecting angle, injecting

delay causes part fuel burning in exhaust

pipe.

Adjust static fuel supply advance angle.

Insufficient air intake, air filter or intake

pipe is blocked.

Remove dust and dirt, and replace air filter element if

necessary.

Worn-out cylinder sleeve and piston ring. Replace parts.

Black

exhaust

gas

Damaged EGR system solenoid (for

diesel engine with EGR system only)

Disconnect the hose (from solenoid) from EGR valve

end, if black smoke stops, it shows solenoid has

damaged and needs to be replaced.

There is water in cylinder or in diesel.

Locate the cause and remove.

White

exhaust

gas

Engine is too cold at cranking, no

combustion in certain cylinder (especially

in winter).

Increase moderately engine Rpm and load and let it

run longer.

Piston ring is stuck or worn-out, and its

elasticity becomes poor. Oil enters

combustion chamber as second piston ring

has been mounted on wrong side.

Disassemble and check piston ring, or replace it if

necessary.

Engine operates on low load for a long

period, clearance between piston and

cylinder sleeve becomes larger, oil enters

combustion chamber.

Increase moderately engine load or disassemble to

check or replace piston ring, piston and cylinder

sleeve.

Blue

exhaust

gas

Excessive oil in oil pan.

Drain excess oil by referring to dipstick hole.

9.6 Low oil pressure

Each diesel engine’s high-speed moving sets should get enough lubricant to reduce wearing and taking heat

away. This will help to avoid parts from stuck and early worn-out. Moreover, lubricating oil can fill up the tiny

clearance in parts (e.g. the one between piston and inner wall of cylinder sleeve), which will improve sealing and

prevent high-pressure air leak, making start-up easy and keeping engine’s original power. Therefore, lubricating

oil should have certain pressure and flow, and should be clean as well.

●Cautions: Engine oil pressure lower than specified value indicates there is fault in lubricating system.

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Never run diesel engine without oil pressure or under lower oil pressure. In those cases, one should shut off engine

to check and remove faults.

Symptoms and causes

Removing procedures

Oil pressure meter indication does not match sensor

output.

Replace them in pair with mated ones from same

manufacturer.

Oil amount in oil pan is not enough.

Add oil to specified level.

Oil strainer or filter is blocked, or filter pressure

adjusting valve is failure.

Clean oil strainer, replace oil filter element, and adjust

or replace pressure-adjusting valve.

Oil pump pressure limiting valve is failure.

Adjust or replace oil pump pressure limiting valve.

Fitting clearances at connecting rod bearing,

crankshaft bearing and camshaft bearing are

excessive.

Replace with new bearing.

Oil pump is worn-out severely or there is other fault

inside.

Check, adjust or replace relevant parts.

Oil viscosity is much low.

Change with specified oil.

9.7 Abnormal coolant temperature or coolant short

Symptoms and causes

Removing procedures

Diesel engine

overheating

（1）Coolant level is too low
（2）Fan belt is loose or broken
（3）Thermostat main valve stuck
（4）Faulty water pump and fan

clutch
（5）Incorrect fuel supply timing
（6）Chocked radiator core

（1）Replenish coolant, check for leak, repair if necessary
（2）Adjust fan belt tension or replace fan belt
（3）Replace thermostat assembly
（4）Replace water pump and fan clutch

（5）Correct fuel supply timing
（6）Clean radiator

Diesel engine

is too cold

（1）Thermostat valve is ajar
（2）Coolant temperature meter is

failure

（1）Replace thermostat
（ 2 ） Measure coolant temperature, replace coolant

temperature meter

Short coolant

often

（1）Radiator is leaking
（2）Radiator hose connector is

loose or hose is damaged
（3）Water pump is leaking

（1）Repair or replace radiator
（2）Tighten clamp or replace hose

（3）Replace water pump assembly

●Notes:

（1）Once a diesel engine gets overheated, it is not allowed to shut down engine or add coolant immediately.

Run engine under no-load at mid-large throttle opening till coolant temperature drops. Then stop engine to

perform checks.

（2）Do not remove radiator cap while engine is still hot to avoid scalding. Use caution when adding coolant.
（3）In the event the cause of overheating cannot be found, contact service station or repairing garage

immediately to prevent other parts from damaged.

OPERATION AND MAINTENANCE MANUAL FOR FOTON VIEW SERIES LIGHT BUS

·150·

9.8 Supercharging system faults

Symptoms and causes

Removing procedures

Lack of

power

(1) Impurity deposits at sealing location on turbine side

(2) Higher oil temperature, insufficient fuel supply and

floating bearing is burnt

(3) Oil leaks from turbine and compressor shaft end due to

blocked or distort oil return pipe.

(4) Supercharger sealing ring is failure due to damage
(5) Turbine rotor lost balance

(6) Turbine and compressor impellers are worn-out and

damaged.

(7) Air filter is blocked (dirty).
(8) Boost compensator breaks air pipe
(9) Dirty intake/exhaust pipes or connectors are leaking.
(10)Supercharger cannot operate well or is damaged.

(1) Change

oil

and

service

supercharger.

(2) Check fuel supply system,

service supercharger.

(3) Service and replace fuel

return pipe.

(4) Replace sealing ring.
(5) Repair and replace turbine

shaft rotor

(6) Check and service.
(7) Service air filter and replace

element

(8) Check

or

replace

air-conducting pipe.

(9) Clean,

check,

repair

or

replace air intake/exhaust
pipes

(10)

Check, repair or replace

supercharger

Higher fuel

consumption

（1）Dirty intake/exhaust pipes or air leak at connections.
（2）Poor supercharger performance

（1）Check or replace part.
（2）Clean, adjust or replace.

Higher oil

consumption

(1)

Supercharger sealing ring is worn out.

(2)

Oil leakage at compressor impeller end.

(3)

Screws at joints of oil intake / return pipe are loose

washers are damaged.

(4)

Oil is of poor quality.

(1) Replace sealing ring.

(2) Check and repair.

(3) Check,

repair

or

replace

washers.

(4)Change

oil

according

to

requirements.

Abnormal

noise

(1) There is too much oil dirt in gas passage on turbine

end, which narrows the passage.

(2) There is too much oil dirt in gas passage on

compressor end, which narrows passage.

（3）Excessive wear on floating bearing, rubbing between
turbine/compressor impeller and case.

(1) Clean or replace.

(2) Clean or replace.

(3) Replace floating bearing.

Vibration due

to rubbing

between

turbine, air

compressor

impeller

(1) Foreign matter enters.

(2) Floating bearing is excessively worn out.

(3) Poor turbine shaft dynamic balance.

（1）Clean or replace.
（2）Replace floating bearing.
（3）Check, repair or replace.

● Cautions:

（1）Be ware of any foreign matters entering intake/exhaust system during fault removing and assembling /

disassembling a diesel engine. Supercharger rotor rotates at a very high speed, its clearance to case is narrow, any

foreign matters either big /small or soft / hard would adversely affect rotor performance and damage its impellers.

Chapter 9 Diesel Engine Faults and Troubleshooting

·151·

The supercharger may subject to abnormal vibration and noise once the impellers are damaged. Shut off engine

immediately when this happens, perform check and repair on supercharger.

（2）Oil leak on supercharger does not warrant that it must be replaced as long as impeller does not rub case

and impeller shaft can rotate freely. Supercharge in this case can be used after oil leak has been removed.

9.9 Starter does not run, weak startup and noise

Symptoms and causes

Removing procedures

Starter motor does

not run

(1) Starter switch and other control circuit are

disconnected.

(2) Poor

contact

between

brush

and

commutator

(3) Starter motor internal disconnected

(1) Check circuit, make connections

reliable.

(2) Adjust brush spring pressure, clean

the commutator.

(3) Check and repair starter.

Weak starter,

cannot startup

diesel engine

(1) Lower battery volume

(2) Poor lead contacting

(3) Burnt damage or oil dirt on commutator

surface.

(4) Worn-out brush or weak brush spring leads

to poor brush contacting with commutator

(5) Poor contacting due to burnt electro-

magnetic switch main contacts,

(6) Worn-out bearing, armature rubs case

(1)Charge

battery

according

to

specifications.

(2)Tighten lead connections.

(3)Polish the commutator surface or

remove the oil filth.

(4)Replace carbon brush or adjust carbon

brush spring.

(5)Polish with grade “0” non-metallic

sandpaper.

(6)Replace bearing.

Engine started

up, while starter

goes on running

with sharp

noise

(1) Bronze contact disk sticks to two contacts

inside starter clutch

(2) Starter motor armature shaft is bent.

(3) Tooth face is scratched to be stuck.

(4) Starter overriding clutch is damaged.

(1)Cut off power immediately, check

circuit and repair contacts.

(2)Cut off power immediately, replace

starter

(3)Cut off power immediately, repair

tooth face.

(4)Cut off power immediately, repair or

replace clutch.

9.10 Alternator does not work, lower/higher charging current

Symptoms and causes

Removing procedures

Alternator does not

work

(1)Wrong circuit connection, disconnected

circuit or poor contacting.

(2)Rotor coil is disconnected.

(3)Commutator diode is damaged.

(4)Poor contacting on carbon brush.

(5)Regulator is damaged.

(1)Check and repair circuit.

(2)Check repair or replace alternator

assembly

(3)Replace commutator diode.

(4)Remove dirt on brush or replace brush.

(5)Repair or replace regulator.

Lower charging

current

(1)Driving belt is loose.

(2)Regulated voltage is too low.

(3)Battery fluid is insufficient or the battery

plates are severely sulphurized.

(1)Adjust belt tension.

(2)Replace regulator.

(3)Add battery fluid to specified level.

Replace battery with severely sulphurized

plates.