Westerbeke BCGB Service Manual page 24

CYLINDER HEAD AND VALVES
Valve Stem and Guides
Measure the clearance between the valve guide and the valve
stem and , if the clearance exceeds the limit, replace the
valve guide or valve, or replace both.
MEASURING VALVE
STEM DIAMETER
VALVE STEM SEAL TO VALVE GUIDE CLEARANCE
Standard Intake
Exhaust
Limit Intake
Exhaust
0.0008 - 0.0020in (0.7 - 0.05mm)
0.020 - 0.0033in (0.50 - 0.085mm)
0.0039in (0.10mm)
0.0059in !0.15mm)
VALVE STEM OUTER DIAMETER
Standard Intake
Exhaust
0.2585 - 0.2591 in (6.565 - 6.580mm)
0.2571 - 0.2579in (6.330 - 6.550mm)
Valve Seat Reconditioning
Before correcting the valve seat, check for clearance
between the valve guide and the valve. replace the valve
guide if necessary.
To recondition, use a valve and seat cutter and a pilot or a
seat grinder, repair so that the seat width and seat angle are
the specified configuration.
After correction, the valve and the valve seat should be
lapped with lapping compound.
INSTALLATION
Valve Stem Seal
VALVE SEAT CONTACT WIDTH
.035 - .051
in
[0.9 -1.3
mmJ
Install the valve spring seat, then using the valve stem seal
installer, install a new stem seal to the valve guide.
Do not use the old valve stem seal.
NOTE:
Use the installer tool to insert the stem seal, improper
installation can cause oil to leak into the cylinder.
VALVE STEM
SEAL INSTALLER
Valve Springs
lr
VALVE STEM
SEAL
Install the valve spring with it's enamel coated side toward
the rocker arm side.
ENAMEL
COATED
SIDE
F"r~---l)PRIIIG RETAINER
NG SEAT
Use the valve spring compressor to compress the valve
;::;
:~.the
valve
~ompre~d'
remove
t h e
REMOVING
RETAINER
LOCKS
Cylinder Head Gasket
Clean the residue of gasket and oil from the gasket mounting
surface of the cylinder block and the cylinder head.
Place a new cylinder head gasket on the cylinder block
facing its identification mark upward.
CYLINDER HEAD GASKET
Engines & Generators
17