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Section 10
General Information
Compression test data
Tests have shown that many factors affect compression pressures. Battery and starter motor
condition, ambient conditions and the type of gauge used can give a wide variation of results for a
given engine.
It is not possible to give accurate data for compression pressure, but tests have shown that the
results should be within 2000/3500 kPa (300/500 lbf/in
Compression tests should only be used to compare between the cylinders of an engine. If one or more
cylinders vary by more than 350 kPa (50 lbf/in
Compression tests should not be the only method used to show the condition of an engine, but they
should be used together with other symptoms and tests.
How to do a compression test
Caution: Before the compression test, ensure that the battery is in good condition and that it is fully
charged. Also ensure that the starter motor is in good condition.
1 Ensure that the valve tip clearances are set correctly.
2 Remove the atomisers.
3 Fit a suitable gauge into the hole in the cylinder head for the atomiser.
4 Disconnect the stop solenoid or put the stop control in the no-fuel position. Operate the starter
motor and note the maximum pressure indicated on the gauge.
5 Repeat for each cylinder.
05/99
Printed in England
© Propriety information of Perkins Engines Company Limited, all rights reserved
2
) 21,0/35,0 kgf/cm
2
2
) 3,5 kgf/cm
, then those cylinders may be faulty.
700 Series
2
for diesel engines.
16
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