Leak Test

TM 10-3930-634-34

not be less than 4.376 inch (fig. 3-77).

Observe water in tank for bubbles, which indicates a

(c) The injector tubes must be removed (fig.

crack or leak.

3-71) prior to refacing the head. After the cylinder

(e) Release air pressure and remove the cylinder

head has been refaced, stamp the amount of stock re-

head from the tank. Remove plates and dummy injec-

moved, on the face of the fire deck, away from the

tors.

combustion or sealing areas.

(f) Dry the head with compressed air.

(d) If a cylinder head has been refaced and new

(3) Inspection.

injector tubes have been installed, pressure check the

(a) Use an accurate straight edge and feeler

head as outlined in test above.

gage to check the transverse warpage at each end and

(e) Inspect the cam follower bores in the cylin-

between all cylinders as illustrated in figure 3-76.

der head for scoring. Light score marks can be cleaned

Also check longitudinal warpage in six places in a simi-

up with crocus cloth dampened with fuel oil. If the

lar manner. The maximum allowable traverse warpage

bores are excessively scored or worn so that the cam

is 0.004 inch and the maximum allowable longitudinal

follower-to-head clearance exceeds 0.006 inch, replace

warpage is 0.005 inch.

the cylinder head.

(b) Do not remove over 0.020 inch of metal

when refacing cylinder head. The distance from the

(f) Inspect the valve seat insets for cracks or

burning. Also check the valve guides for scoring.

top to the bottom (fire deck) of the cylinder head must

3-54