TM 5-3810-295-34
e
Inspect the cam follower bores for scoring or wear. Light score marks may be cleaned up with crocus cloth
wet with fuel oil. If the bores are excessively worn so that the cam follower to head clearance exceeds 0.006 inch, replace
the cylinder head.
f
Check the cylinder head for leaks as follows.
(1) Install injector hole tubes (54) and injector tube seal rings (55) in the cylinder head.
(2) Sea off the water holes in the head with steel plates and suitable rubber gaskets held in place with bolts.
(3) Install dummy or scrap injectors to insure seating of the injector tubes. (Dummy injectors may be made
from scrap nuts and bodies.)
(4) Drill and tap into one of the temporary water hole plates for an air hose connection and apply 80 to 100
psi pressure with the head immersed in a tank of water heated to 180 to 200F., for a period of 20 minutes. Observe for
air bubbles which indicate leaks or cracks.
(5) Replace the head if cracks are evident. Replace any leaking fuel injector tubes.
g
Inspect valve seat inserts for cracks or burning.
h
Inspect the rounded ends of the push rods for wear. Replace any push rod that is worn or bent.
i
Check the push rod springs and replace the springs when a load of less than 250 pounds compresses the
springs to a length of 2 9/6 inches.
j
Replace all pitted or fractured valve springs.
k
Check the valve springs on an accurate spring tester. Replace any spring that compresses to 1.93 inches
under a load of 25 pounds. The difference in load between a pair of springs must not exceed 6 pounds or the valve bridge
will be unbalanced.
l
Inspect valve caps and spring seats for wear, Replace worn or damaged parts.
m Clean carbon from the valve stems and wash the valves in cleaning solvent. Check the valve stems for
scratches and scuff marks, and inspect the valve races for ridges, cracks or pitting. If valve heads are warped, replace the
valves. Valves may be refaced. However, to provide sufficient valve strength and spring tension, the edge of the valve at
the valve head must not be less than one thirty-seconds of an inch and must be within the specifications shown in figure 4-
3. The angle of the valve face, and the valve seat insert, must be exactly 30 degrees.
NOTE
Valve seat inserts must be ground in place in the cylinder head.
Figure 4-3. Exhaust valve installation specifications.
Inspect valve guides for fractures, scoring or excessive wear. Check valve-to-guide clearance. If clearance exceeds 0.005
inch, replace the valve guides.
4-8. Reassembly
a. Refer to figure 4-1. Install water nozzles (56) in the cylinder head. Be sure the ports in the bottom of the head are
positioned as shown in figure 4-4.
4-4
