TM 5-3810-306-34
4. INSPECT VALVE SEATS.
c.
Check valve spring tension. A load of 101.2 to
115.5 lbs (450 to 513.5 N) is required to
a. Inspect valve seats for cracks or burnt spots.
compress spring to a height of 2 in. (50.8 mm).
Replace damaged seats.
Replace springs out-of-limits.
b. Install valves in their respective bores, and using
6. INSPECT COMBUSTION FACE FOR CRACKS.
gauge block, measure depth of valve from
cylinder head deck. Minimum valve depth .035
a. Cracks that extend from the injector bores, away
in. (.89 mm). Maximum valve depth .056 in.
from the valve seats and are not over .3937 in.
(1.42 mm).
(10 mm) long are acceptable.
b. Cracks that extend from the injector bores
NOTE
toward the valve seats or cracks between the
valves are unacceptable.
Replace cylinder
Make sure seats are clean before
head.
measuring valve depth.
REPAIR:
c.
If the valve depth is out-of-limits, before
replacing the valve seat, try replacing the old
1. REFACE ALL REUSED VALVES.
valve with a new valve. If the depth is in limits
with the new valve, proceed with the seat
a. Valve seat angle Intake: 30 degrees Exhaust: 45
grinding procedure using the new valve with the
degrees
old seat. If the valve depth is still out-of-limits,
even with the new valve, replace the valve seat.
b. Minimum valve head rim thickness .0591 in.
After replacing the seat, recheck the valve depth
(1.50 mm)
with the old valve to determine if it can be
reused. If not, replace valve.
c.
Valve stem tips as required for flatness
5. INSPECT VALVE SPRINGS.
2. GRIND VALVE SEATS.
a. Inspect springs for breaks
and
distortion.
a. Grind valve seats to remove all scores,
Replace damaged springs.
scratches and burns. Seat angle: Intake (30
degrees). Exhaust (45 degrees).
b. Measure valve springs. Approximate free length
2.585 in. (65.66 mm). Minimum inclination .039
b. Measure valve depth.
in. (1.0 mm). Replace springs out-of-limits.
c.
Apply a coat of valve lapping compound to each
valve and lap each valve to its corresponding
seat.
d. Remove valves and clean compound from
valves and seats.
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