A Series Diesel Engine Base Engine Components 158
Compression Check
If the air and fuel system are functioning correctly,
perform a compression check to determine whether
the problem is:
z Piston ring sealing
z Valve sealing
z Head gasket sealing or a crack in the
cylinder head
Piston Ring Seal
If the compression is low but can be increased
significantly by squirting oil into the cylinder, the
cause of low compression is inadequate sealing
between the rings and the cylinder walls.
Normal compression is 3430 kPa [497 PSI] at 250
RPM cranking speed. A 26 kPa [383 PSI] difference
between cylinders indicates a compression seal
problem.
Valve Sealing
If the compression is low on one or more non-
adjacent cylinders and the pressure cannot be
increased by oiling the rings, poor valve sealing is
to be suspected.
Valve leakage is often audible from the intake and
exhaust manifold.
To Next Page
Loading...
