Westerbeke 12C- TWO Operator's Manual page 46

ENGINE ADJUSTMENTS
NOTE:
WESTERBEKE ':;'commends that the/allowing
engin~
adjust-
. ments be peiformed by a competent engine mechanic. The information
below is provided to assist the mechanic.
ENGINE COMPRESSION
Check; the engine's compression pressure at 500 and 1250
openiting'houis or whenever engine perfonnance is reduced.
Remove each glow plug and check each cylinder's
compression pressure. The engine's cranking speed is
at 280 rpm.
MEASURING COMPRESSION:
Check LIe compression pressure. To do this wann the engine,
remove all fuel injectors, or glow plugs, disconnect the fuel
shut-off solenoid wire, and install a compression adapter in
the injector hole or glow plug hole. Connect a compression
tester on the adapter and cnmk the engine with the starter
motor until the pressure reaches a maximum value. Repeat
this process for .each cylinder. Look for cylinders with dra-
matically Cat least 20%) lower compression than the average
of the others. Compression pressure should not differ by
more than 35.5 psi C2.5 kglcm') at 280rpm.
If a weak cylinder is flanked by healthy cylinder, the problem
is either valve or piston related. Check the valve clearances.
for the weak cylinder, adjust as needed and test again. If the
cyliilder is still low, apply a small amount of oil into the
. cylinder to seal the rings and repeat the test. If compression
comes up - the rings are faulty. .
Abnormally high readings on all cylillders indicates heavy
carbon accumulations, a condition that might be
accompanied by high pressures and noise.
NOTE: In case of severe vibrations and detonation noise, the
cause may be fuel injector problems, see
FUEL
INJEC~
TORS. Poor fuel quality. contaminates and loss of positive
fuel pressure to the injection pump will result in injector
faults. .
When re-installing the glow plugs use anti-seize compound.
COMPRESSION VALUES
STANOARD (AT 280 RPM) 398.16 PSI (28Kg/cm')
MINIMUM (AT 280 RPM) 355.5 PSI (25Kg/cm"
MAXIMUM ACCEPTABLE DIFFERENCE BETWEEN 35.5 PSI (2.5 Kg/em"
DRIVE BELT ADJUSTMENT
Excessive drive belt tension can cause rapid wear of the belt
and reduce the service life of the fresh water pump's bearing.
A slack belt or the presence of oil on the belt can cause belt
slipping, resulting in high operating temperamres.
The drive belt is properly adjusted if tlie belt can be
deflected no less thim 3/8 inch ClOmm) and no more than 1/2
inch (l2mro) as the belt is depressed with
the
thumb at the
midpoint between the tv(o pulleys on the longest span of the
beli. A spare bolh,r belts should always be carried on board.
A
WARNING:
Never attempt
to
check
or
adjust the
drive helt's tension while the engine is in operation.
Adjusting Belt Tension
1. Loosen the alternator pivot bolt.
2. Loosen the alternator alljusting bolt.
3. With the alternator loose, swing it outward
l1I1i:i!
the drive
belt is tensioned correctly.
4. Tighten both bolts.
S.
Check the tension again after the engine has been in
. operation.
Engines & Generators
39