TM 5-3810-306-34
b. Measure diameter of valve stems in at least
NOTE
three equally spaced places. Minimum diameter
.3724 in. (9.46 mm). Maximum diameter .3740
An inferior quality wire wheel will lose
in. (9.50 mm). Replace valves if out of limits.
steel bristles during operation,
causing additional contamination.
c.
Check valve stem tips for flatness and measure
valve head rim thickness. Minimum thickness of
CAUTION
rim .0591 in. (1.50 mm). Valve stem tips and
valve head rims may be resurfaced if determined
Use only clean low pressure (30 psi
suitable.
max) compressed air for drying parts.
If unavailable, allow parts to air dry or
wipe with clean, lint-free cloth.
2. INSPECT VALVE GUIDES.
6. WASH CYLINDER HEAD IN HOT SOAPY WATER
a. Inspect valve guides for scuffing or scoring.
SOLUTION 88C (190F). AFTER RINSING, USE
COMPRESSED AIR TO DRY CYLINDER HEAD.
b. Measure valve guide bores. Minimum diameter
.3756 in. (9.539 mm). Maximum diameter .3763
CAUTION
in. (9.559 mm).
Wear eye protective goggles when
c.
Replace damaged valve guides.
using rotating tools for cleaning
purposes.
3. INSPECT CYLINDER HEAD DECK.
7. CLEAN VALVE HEADS WITH A SOFT WIRE
WHEEL INSTALLED IN A DRILL OR BENCH
a. Measure cylinder head deck for distortion.
GRINDER.
Maximum distortion is 0.003 in. (0.075 mm)
overall end to end or side to side.
NOTE
b. If distortion exceeds limits, a maximum of 0.040
Keep valves in a labeled rack to
in. (1.0 mm) can be machined from combustion
prevent mixing.
surface of cylinder head or cylinder head must
be replaced.
8. POLISH VALVE STEMS WITH CROCUS CLOTH
AND DIESEL FUEL.
d. If cylinder head is machined, place valve in
respective bore and check valve depth
dimension. Minimum depth is 0.043 in. (1.09
INSPECTION:
mm), maximum is 0.064 in. (1.62 mm).
1. INSPECT VALVES.
d. If valve depth is less than minimum, machine
valve seat. (Refer to page 4-13.)
a. Inspect for abnormal wear on heads and stems,
and bent valves. Replace damaged or worn
valves.
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