Chery Tiggo 5 (T21). Service manual — part 108

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Engine Service Platform

RCH0000057

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DIAGNOSIS & TESTING

Engine Performance Diagnosis

HINT:

 Use the table below to help determine the cause of the problem. Check each suspected area in sequence.

 Repair or replace the faulty components, or adjust as necessary.

Symptom

Suspected Area

See page

Valve mechanism noise

Engine oil (oil level high or low, oil lean or
rich)

13-11

Cam

07-49

Valve spring seat (excessive runout)

07-57

Valve (excessive clearance between valve
and guide)

07-60

Connecting rod noise

Engine oil (low pressure)

13-10

Engine oil (lean)

13-11

Connecting rod bearing cap (loose fixing
nut)

07-98

Connecting rod (misaligned)

07-97

Connecting rod bearing shell (excessive
radial clearance)

07-91

Connecting rod journal (out-of roundness)

07-91

Main bearing noise

Engine oil (low pressure)

13-10

Engine oil (lean)

13-11

Main bearing shell (excessive clearance)

07-90

Crankshaft axial clearance (excessive)

07-90

Crankshaft journal (out-of roundness or
worn)

07-89

Flywheel or clutch (loose)

07-42

Oil loss or spark plug blockage

Piston ring (worn, scratched or damaged)

07-84

Piston ring groove (fouled)

07-87

Valve oil seal (worn or damaged)

07-57

Valve (excessive clearance between valve
and guide)

07-60

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Inspection

1. Check coolant (

See page 12-12

).

2. Check engine oil (

See page 13-9

).

3. Check battery (

See page 16-7

).

4. Check air filter.

a. Remove the air filter element.
b. Visually check that there is no dirt, blockage or damage in the air filter element.

HINT:

 If there is any dirt or blockage in the air filter element, clean it with compressed air.

 If any dirt or blockage remains even after cleaning the air filter element with compressed air, replace it.

5. Check spark plugs (

See page 14-12

).

6. Test cylinder compression pressure.

 Cylinder pressure is the main index to judge engine operation and also can be used to judge definitely

whether some system of engine operates well or not. Therefore, it is necessary to perform the
measurement of cylinder pressure when servicing the engine.

 Ensure that battery is fully charged and the engine starter is in good operating condition. Otherwise the

indicated compression pressure used for diagnosis may be invalid.

Measurement Procedures

a. Turn off all the electrical equipment and ignition switch.
b. Remove the engine trim cover assembly (

See page 10-10

).

c. Move away the high-voltage cables for each cylinder.

 Remove the clamp (arrow) from crankcase

ventilation hose, and disconnect the connection
between crankcase ventilation hose and cylinder
head cover.

 Move away the crankcase ventilation hose.
 Loosen the high-voltage cables (1) in order, pull

them upward from spark plug holes, and move
them to one side.

CAUTION

 Recommended compression pressure is only used as a guide for diagnosing engine malfunction.
 Never determine causes of low pressure by disassembling engine unless there are some malfunctions.

CAUTION

 Select cylinder pressure gauge with accurate reading and reset it to zero. Otherwise it will affect

accuracy of reading.

1

RT21140110

CAUTION

 Be careful not to damage high-voltage cables when pulling them upward.

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d. Disconnect all fuel injector connectors.
e. Remove the spark plug (

See page 14-12

).

f. Slowly screw the cylinder pressure gauge joint

vertically into the spark plug hole. Do not tighten it
excessively to prevent difficult removal.

g. With transmission in neutral position, release the accelerator pedal fully, then start the engine and keep

it racing for 3 to 5 seconds to record the measured pressure value.

h. Press the bleeder button of cylinder pressure gauge to reset it to zero. Measure three times in the same

way and take the average.
Standard value for cylinder pressure: 10 - 13.5 bar

Cylinder Pressure Value Judgement
 Correct cylinder pressure

Standard cylinder pressure value is between 10 and 13.5 bar and will drop slightly with the using of
engine. But the lowest value cannot be below 9 bar and the pressure difference between each
cylinder should not be above 3 bar.

 If cylinder pressure of engine is lower than the standard value, it indicates that cylinder pressure is

insufficient. Add a small amount of engine oil through spark plug hole and perform measurement
again.
If pressure increases after adding oil, the piston ring or cylinder bore may be worn or damaged.
If pressure remains low, the valve may be stuck or not properly installed or there is air leakage from
cylinder head gasket.

i. Install the spark plug (

See page 14-12

).

j. Connect all fuel injector connectors (

See page 08-26

).

k. Install the high-voltage cables.

RT21070010

CAUTION

 DO NOT screw cylinder pressure gauge excessively to prevent difficult removal.

CAUTION

 During measurement, do not turn ignition switch to "START" for more than 10 seconds. Otherwise the

engine may be damaged.

 Ensure that battery is fully charged when cranking engine. Correct cylinder pressure can be measured

only when engine is running at 180 - 250 r/min.

 Use the same method to measure pressure of other cylinders.