Cylinder Compression Pressure Test (2.4L) - Chery Tiggo 2009 Service Manual

CONDITION
Oil Pressure Drop
Oil Leaks
Oil Consumption Or Spark Plugs
Fouled
Cylinder Compression Pressure Test
• The result of a cylinder compression pressure test
can be utilized to diagnose several engine malfunc-
tions.
• 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 neces-
sary.
− 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 880 kPa and not vary more than 25 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.
Chery Automobile Co., Ltd.
DIAGNOSIS & TESTING
POSSIBLE CAUSES
1. Low oil level.
2. Faulty oil pressure sending unit.
3. Low oil pressure.
4. Clogged oil filter.
5. Thin or diluted oil.
6. Excessive bearing clearance.
1. Misaligned or deteriorated
gaskets.
2. Loose fastener, broken or porous
metal part.
3. Misaligned or deteriorated cup or
threaded plug.
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.
CORRECTION
1. Check engine oil level.
2. Install new sending unit.
3. Check sending unit and main
bearing oil clearance.
4. Install new oil filter.
5. Change oil to correct viscosity.
6. Measure bearings for correct
clearance.
1. Replace gasket.
2. Tighten, repair or replace the part.
3. Replace if necessary.
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).
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