TM 55-1930-209-14&P-21
6-16 Cylinder head cleaning test, inspection and repair
a. Cleaning. Wash cylinder head with cleaning solvent and dry with compressed air.
b. Test, Inspection and Repair
(1) After cylinder head has been disassembled, remove oil gallery plugs and thoroughly steam clean cylinder
head.
(2) Use an accurate straight edge and feeler gage to check transverse warpage at each end and between all
cylinders. Also, check longitudinal warpage in six places. Maximum allowable transverse warpage is 0.004 inch and
maximum allowable longitudinal warpage is. 006 inch.
CAUTION
Do not remove over 0.020 inch metal when refacing cylinder head. Distance from top to bottom
(fire deck) of cylinder head must not be less than 4.376 inches.
NOTE
Injector tubes must be removed prior to refacing head. After cylinder head has been refaced,
stamp amount of stock removed, on face of fire deck, away from combustion or sealing areas.
(3) Inspect cam follower bores in cylinder head for scoring. Light score marks can be cleaned up with
crocus cloth dampened with fuel oil. If bores are excessively scored or worn so that cam follower-to-head clearance
exceeds 0.006 inch, replace cylinder head.
(4) Inspect valve seat inserts for cracks or burning. Also, check valve guides for scoring.
(5) Inspect water nozzles to make sure they are not too loose in cylinder head.
(6) Prepare cylinder head for a leak test by sealing all water holes in head with steel plates and rubber
gaskets.
(a) Install dummy or scrap injectors and tighten injector clamp bolts to 2025 lb-ft torque.
(b) Drill and tap one steel plates for an air hose connection and apply 40 psi air pressure to water
jacket.
(c) Immerse head in a tank of water previously heated 180° to 200°F for 20 minutes. Observe water in
tank for bubbles, which will indicate a crack or leak.
(d) Release air pressure and remove cylinder from tank. Remove plates and dummy injectors.
(e) Dry head with compressed air.
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