Westerbeke 6.5 MCG Service Manual page 18

CYLINDER HEAD AND VALVES
Use pliers
to
remove the valve stem seals. Do not reuse the
stem seals.
CYLINDER HEAD INSPECTION
Before cleaning check the cylinder head for water leaks,
cracks and other possible damage.
Clean by completely removing the oil, scaling, carbon and
sealant After flushing the oil passage, blow air thru
to
ensure
that no portion of the oil passage is clogged.
To check the cylinder head bottom surface for flatness and
distortion,
as indicated in the diagram, use a straight edge
and a feeler gauge. If distortion exceeds the limit correct
by grinding.
CHECKING CYUNDER HEAD FLATNESS
I
CYLINDER HEAD flAlNESS
Standard O.OD191n (0.06mm) Limit O.DD791n (0.2mm)
CYLINDER HEAD GRINDING UMIT .
D.0079in (D.2mm}
Total resurfacing_ depth of cylinder head and block
CYLINDER HEAD HEIGHT (NEW)
4.287- 4.2961n (108.9 -109.1mm)
A
CAUTION:
No more than 0.079Jn (0.2mm) of
stock may be removed from the cylinder head and
cylinder block mating surfaces In total.
See the STANDARDS AND UMll'S CHART for cylinder
head rework dimensions of the valve seat hole.
VALVE ASSEMBLY INSPECTION
Valve StemNalve Seat
If the valve stem is bent or worn, replace
the
valve. Check
contact between the valve and valve seat by applying a thin
coat ofPrussion Blue (or Redhead) on the valve seat contact
face, then insert the valve into the valve guide and press-fit
the valve on the valve seat. Do not rotate the valve.
Check if the valve seat contact face contacts the center posi-
tion ef
the
valve contact face. If it is not correct concentric,
correct the valve seat. If the margin is out of the limit, replace
the valve.
THICKNESS OF VALVE HEAD MARGIN
standard
Intake D.0391n (1.Dmm)
Exhaust D:D51in (1.3mm)
CONTACT WllH
VALVE SEAT
!It be at center
of
seat)
VALVE LENGTH: Intake 3.961ln (100.6mm)
'Exhaust 3.968in (1 oo.amm)
VALVE SEAT WIDTH OF CONTACT·
Standard 0.0361n- 0.051 (0.9 -1.3mm)
Valve Spring
Umit
0.0201n (r0.5mm)
O.D311n (O.Bmm)
---r
• VALVE
LENGTH
Measure the
free
height of the valve spring and replace the
spring if it is out of limit.
VALVE SPRING FREE LENGTH
standard 1.8231n (46.3mm)• _ _ _ _ Limlt 1.783in (45.3
mm)
Also check
the
spring for squareness and if it exceeds the
limit replace the spring.
'VALVE SPRING SQUARENESS
Engines & Generators
16