Engine Adjustments; Tightening The Cylinder Head; Valve Clearance Adjustment; Engine Compression Test - Westerbeke 7A-1 Operator's Manual

ENGINE ADJUSTMENTS
NOTE:
WESTERBEKE recommends that the following engine adjustments
be performed by a competent engine mechanic. The information below
is provided to assist the mechanic.
TIGHTENING THE CYLINDER HEAD
After the initial break-in period (approximately 50 hours),
retorque the cylinder head nuts.
Do
this when the engine is cold.
1. Remove the cylinder head cover and gasket.
2. Retighten the four cylinder head nuts in an X-pattern
sequence as shown in the illustration. Start with any nut.
Before applying the torque to a nut, loosen it 114 to 112 a
tum, then apply the torque. See TORQUE
SPECIFICATIONS for the proper torque.
3. Reinstall the cylinder head cover and gasket. Insert new
plastic washers under the two nuts and tighten to the
specified torque.
VALVE CLEARANCE ADJUSTMENT
Check the valve clearances after the first 50 hours of operation and
every 600 hours thereafter.
NOTE:
Tighten the cylinder head bolts to their specified torque
before adjusting the valve clearances (see TIGlffENING THE
CYUNDER HEAD).
Adjust the valve clearances when the engine is cold. The
clearance is 0.2 mm (0.008 in.) for both intake and exhaust valves.
1. Remove the cylinder head.
2. Check to make sure the automatic decompression
device is in its normal operating position, i.e. not activated
(see illustration).
POINTER
' - - - l - ' H - -
AUTOMATIC DECOMPRESSION
DEVICE IN THE NORMAL
OPERATING POSITION
~
~
="~JJ=======
3. Set the piston at the TDC of the compression stroke.
4. Loosen the locknuts on the valve setting screws
(see illustration).
5. For each valve, insert a 0.2 mm (0.008 in.) feeler gauge
between the valve stem and the rocker arm, and adjust the
clearance until a slight drag is felt on the gauge when it is
pulled out.
6. Tighten the locknut while holding the setting screw with
a screwdriver.
7. Recheck the clearance.
ENGINE COMPRESSION TEST
To check the engine's compression pressure, warm up the engine,
shut off the raw water through-hull, remove the fuel injector, and
install a compression adapter in the injector hole. Connect a com-
pression tester on the adapter and
crank
the engine with the starter
motor until the pressure reaches a maximum value.
Compression pressure at 350 rpm:
Minimum: 435.0 psi (30.6 kg/cm
2 )
Standard: 478.5 psi (33.6 kg/cm
2 )
ADAPTER
~INJECTOR
HOLE
If
the pressure is weak, the problem is either valve- or piston-
related. Check the valve clearance, adjust as needed, and test
again. If the compression is still low, apply a small amount of oil
into the cylinder to seal the rings, and repeat the test. If the
compression comes up, the rings are faulty.
An
abnormally high reading indicates heavy carbon accumulation,
a condition that might be accompanied by high pressure and noise.
NOTE:
In case of severe vibrations and detonation noise, have the
injector checked and overlw.uled by an authorized fuel injection
service center. Poor fuel quality, contaminants and loss of positive
fuel pressure to the injection pump will result in injector faults.
Engines & Generators
35