Service manual

CYLINDER HEAD
Cylinder Head Inspection
Clean the cylinder and the cylinder block surface from which
the gasket has been removed. Carefully check the cylinder
head for cracks or
any other damage as shown below. Use a
straightedge and a thickness gauge to check the surface for
distortion and warpage.
Check the valve guides and valve contact surfaces.
Cylinder head distortion repair limit: 0.004 in {0.1 mm)
Valve Seat Repair
If a valve seat is found defective, reface it or have a machine
shop install a new seat.
Sinkage of valve
Standard 0.019in (0.5mm)
Limit 0.059in (1.5mm)
NOTE: When checking valve sinkage, the valve guide must be
in normal condition. Resurface the valve seat so that it con-
tacts the mid-ponion
ofthe valve face.
Check guides for
wear and damage.
/
VALVE SINKAGE
Check valve contact, wear,
damage and the sink of the seat face.
Valve Guide Replacement
Check for cracks; damage
and water leaks. Remove all
oil,
sludge, sealant
and carbon deposits.
If a valve guide is found defective, replace it.
1. Remove the valve guide by pressing at its upper end and
pull it out to the valve seat side.
2. Install the valve guide by press fitting the guide from the
upper side of the cylinder head to a height of 14mm
(±0.5) from the valve spring seat face.
D.25mm-~-f
(0.984 in)
0.12 mm
(0.472 in)
....,.l:--+-- 6.6 :1:0.015 mm
(0.295 in)
PRESS-ATTING THE VALVE GUIDE
so·
\
RESURFACING THE VALVE SEAT
(INTAKE AND EXHAUST)
Installing The Cylinder Head
f'Width of Valve Contact
, 1.3-1.8mm
/', ',
Installation of the cylinder head is in the reverse order of
removal. Pay attention to the following.
1. Renew the cylinder head gasket. No application of
sealant is necessary. On the upper front of the gasket is
the engine model to which the gasket is applicable. Be
careful not to confuse it with a gasket for another engine
model.
2; Tighten the cylinder head bolts in the numerical order
shown going through that order two or three times.
Tighten each bolt a little at a time
untiJ. all are tightened
to the specified torque.
CYUNDER HEAD BOLT TIGHTENING SEQUENCE
FRONT
I'WIWESTERBEKE
l Engines & Generators
10