CONDITION POSSIBLE CAUSE CORRECTION
Oil Leaks
1. Misaligned or deteriorated
gaskets.
2. Loose fastener, broken or porous
metal part.
3. Misaligned or deteriorated cup or
threaded plug.
1. Replace gasket.
2. Tighten, repair or replace the part.
3. Replace if necessary.
Oil Consumption Or Spark Plugs
Fouled
1. PCV system malfunction.
2. Worn, scuffed or broken rings.
3. Carbon in oil ring slots.
4. Rings fitted too tightly in grooves.
5. Worn valve guide(s).
6. Valve stem seal(s) worn or
damaged.
1. Check system and repair if
necessary.
2. Hone cylinder bores. Install new
rings.
3. Install new rings.
4. Remove rings and check grooves.
If groove is not proper width, replace
piston.
5. Replace cylinder head.
6. Replace seal(s).
Cylinder Compression Pressure Test
• The result of a cylinder compression pressure test can be utilized to diagnose several engine malfunctions.
• Ensure the battery is completely charged and the engine starter motor is in good operating condition. Otherwise
the indicated compression pressures may not be valid for diagnostic purposes.
− Check engine oil level and add oil if necessary.
− Disconnect the spark plug wires.
− Remove all spark plugs from engine (as spark plugs are being removed, check electrodes for abnormal
firing indicators fouled, hot, oily, etc.).
− Record cylinder number of each spark plug for future reference.
− Disconnect fuel injector electrical connectors.
− Be sure throttle blade is fully open during the compression check.
− Insert compression pressure adaptor or the equivalent into each spark plug hole in cylinder head.
− Crank engine until maximum pressure is reached on gauge. Record each cylinder pressure.
− Compression should not be less than 900 kPa and not vary more than 30 percent from cylinder to cylinder.
− If one or more cylinders have abnormally low compression pressures, repeat the compression test.
− If the same cylinder or cylinders repeat an abnormally low reading on the second compression test, it could
indicate the existence of a problem with the cylinder in question.
NOTE :
The recommended compression pressures are to be used only as a guide to diagnosing engine problems. An engine
should not be disassembled to determine the cause of low compression unless some malfunction is present.
Cylinder Head Gasket Test
• A cylinder head gasket leak can be located between adjacent cylinders, between a cylinder and the adjacent
water jacket or from an oil passage to the exterior of the engine.
• Possible indications of the cylinder head gasket leaking between adjacent cylinders are:
− Loss of engine power
− Engine misfiring
− Poor fuel economy
• Possible indications of the cylinder head gasket leaking between a cylinder and an adjacent water jacket are:
− Engine overheating
− Loss of coolant
− Excessive steam (white smoke) emitting from exhaust
− Coolant foaming
DIAGNOSIS & TESTING
02
02–15
Chery Automobile Co., Ltd.
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