b. Disassemble the engine head assembly. Using a suitable wrench, remove the machine bolt,
the lock washer, the backstop washer, the engine valve backstop, and the engine valve from the engine
head.
c. Service the engine head assembly by following these procedures:
Step 1.
Inspect the machine bolt for stripped threads and the backstop washer for
corrosion and burred or worn index tabs. Remove corrosion with a rag and fog
oil. Replace damaged parts with spare parts and turn in the damaged parts to
organizational maintenance.
Step 2.
Inspect the engine valve for bent, broken, or burnt petals. Replace with spare if
petals are broken or bent. Clean the valve on a lapping board to remove burns
from the petals.
Step 3.
Inspect the engine head for wear or burrs on the index slots, for clogged ports, and
for carbon deposits on the valve seating face. Clean the ports with the twisted
corner of a rag soaked in dry cleaning solvent. If badly damaged, inform
organizational maintenance.
Step 4.
Remove carbon deposits from the valve seating face. Place a small amount of fog
oil on a lapping board and rub the valve seating face on the fog oil using a figure-
eight motion (Figure 2-2); simultaneously rotate the engine head to ensure even
pressure and to prevent uneven wear.
d. Reassemble the engine head assembly by following these procedures:
Step 1.
Assemble the lock washer, the backstop valve, and the engine valve backstop on
the machine bolt.
Step 2.
Position the engine valve on the valve seating face so that the index slots on the
engine valve align with those on the valve seating face.
CM3305
2-4
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