Cleaning, Inspection, and Repair - TM-10-3930-632-340075

TM 10-3930-632-34

a bell-mouthed shape or guides that have a maximum

WARNING

diameter of more than 0.3133 (intake) and 0.3150

Dry cleaning solvent, PD4-680, used to clean

If the valve guides are worn or damaged, drive

parts is potentially dangerous to personnel and

out the guides from the combustion side, using a driver

property. Avoid repeated and prolonged skin

that is slightly smaller than the external diameter of the

contact. Do not use near open flame or

excessive heat. Flash point of solvent is 100 F.-

guide (fig. 9-7). With the driver, drive in new guides from

138 F. (39 C.-59 C.).

the combustion side. When properly seated, valve guide

tops will be 7/8 inches from the top of the block (fig. 9-8).

9-12.

Cleaning, Inspection, and Repair

Clean the valves, valve springs, valve tappet

assemblies and valve stem caps with cleaning solvent P-

D-680 and dry thoroughly. Remove carbon deposits with

a wire brush.

Clean the valve guides installed in the block

with a valve guide cleaner or wire brush. Remove all

lacquer and other deposits.

Clean the valve seats with a wire brush.

Inspect the valves for cracks, bent stems,

distortion, and wear (table 9-1). If the valves are not

seriously damaged, regrind them. After grinding, the

valve head thickness must be at least 50 percent the

thickness of a new valve. Replace the valves if they are

ground to less than this amount. Check the reground

valves on V-blocks with an indicator. The contact face

must be true with the stem to within 0.002 inch. Repeat

refacing operation if necessary.

Check for loose or worn valve guides. Check

the internal diameter of the valve guide with a telescope

gage and a micrometer. Replace guides that are worn to

Figure 9-7. Removing Valve Guides.

9-7