TM 5-3895-346-14
TROUBLESHOOTING
ENGINE OVERHAUL
SUGGESTED REMEDY
1. A worn or eroded valve seat may be lapped, but not excessively as this would reduce thickness of the part
causing a deviation from the valve stackup dimension.
2. If the valve seat is chipped at the point of contact with the valve, lap the surface of the seat and the ID of
the hole. Mount tool J 7174 in a drill motor and place the valve seat on the pilot of the tool, using a small
amount of lapping compound on the lapping surface. Start the drill motor and apply enough pressure to bring
the seat to the point of lap. Check the point of lap contact after a few seconds. If the edge of the hole appears
sharp and clear, no further lapping is required. Excessive lapping at this point will increase the size of the hole
and lower the injector valve- opening pressure.
3. Replace the valve seat.
4. Replace the valve or valve stop.
5. Replace the spring. Check the valve cage and valve stop for wear; replace them if necessary.
6. Disassemble and clean the injector.
7. Replace the valve cage.
8. Carbon in the tip should be removed with tip reamer J 1243 which is especially designed and ground for this
purpose.
9. Check the size of the spray tip orifices. Then, using tool J 4298-1 with the proper size wire, clean the
orifices.
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