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TM 5-4210-229-14&P
6-6.
CYLINDER HEAD AND VALVES MAINTENANCE (Continued)
NOTE
Valve guides must be thoroughly cleaned
prior to valve installation.
(1) Coat a brush (Appendix D, Item 9) (which has a
slightly larger diameter than the I.D. of the valve
guide) with soap and water.
(2) Insert brush into I.D. of valve guide and with a
turning motion, run the brush through to insure
removal of gum, carbon deposits and rust
preventive from the guide and spiral groove.
NOTE
When installing valves and retainers do not
use grease. Grease may stop the flow of
lubricating oil into the valve guide and cause
valve guide wear.
(3)
Thoroughly coat guide with clean lubricating oil
(Appendix D, Item 37) after cleaning operation is
complete.
AlI valve guides furnished as replacement
parts are reamed to size; however it is
necessary to ream guides to specified
size after installation to remove any burrs
or
slight
distortion
caused
by
the
pressing operation. Be extremely careful
not to remove too much material. Always
clean guides after this operation.
(4)
After cleaning all valve guide bores, position
alight at bottom of valve guide bore; examine
walls for burning, cracking or excessive wear.
(5)
Measure I.D. of valve guide at several points.
Valve guide I.D. maximum limits are:
0.3750 in.
(9.525 mm)
(6)
Replace any guides which are burned, cracked,
worn beyond limits, or without rifling.
(a) Remove valve guides with valve guide remover.
NOTE
Install valve guides with (internal) threaded
portion down. The 30 degree chamfer at the
top of the guide is intended to allow excess
oil to drain away from the top of the guide
and the threads are intended only to
distribute the small amount of oil which
enters the guide, not to introduce oil.
Inverting the guides can lead to excessive
oil consumption.
(b)
Use valve guide installer to install new guide.
Keep valve guide recession from cylinder head
surface at the maximum limits specified.
INTAKE
EXHAUST
1.227 in (31.17 mm)
1.307 in (32.20 mm)
c.
Valves inspection.
(1)
Remove residue from valve springs, valve head
and stem.
Cleaning solvent, (Appendix D, Item 54), is
both toxic and flammable. Keep off skin.
Use only in a well-ventilated area and avoid
prolonged breathing of vapors. Keep away
from open flames.
Do not use steel brushes, for these will
scratch the surface and lead to valve failure.
(a) Clean with solvent (Appendix D, Item 54) and a
brass wire brush (Appendix D, Item 7).
6-9
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