TM 10-3950-672-24-2
In-Chassis Overhaul
The remaining procedures in this manual are organized for an in-chassis overhaul. An in-chassis overhaul includes:
Replacing piston rings
Grinding valves
Testing injectors
This manual gives the procedures to replace the piston rings, rod bearings, main bearings, and grinding the valves. The
procedures to test the injectors are given in the Shop Manual, Bulletin Number 3810206.
Segments of the procedures can also be used to replace individual components when required.
The condition of the cylinder block and crankshaft is the limiting criteria for in-chassis overhaul. If there is reason to
believe that either are severely damaged, the engine should be removed for major overhaul.
Prior to deciding on an in-chassis overhaul, inspect the air intake for evidence of ingestion of particles that could have
severely damaged the cylinder walls. Check the oil and oil filter to be sure the lube system is not thoroughly
contaminated with metal. Also check for rust in the coolant which can indicate build up in the passages in the cylinder
block and require the block to be removed for cleaning. Also consider the condition of other components, particularly
those that are more difficult to replace in-chassis; e.g. the camshaft rear seal, etc. The combination of in-chassis
overhaul and time to repair those components may exceed the time required to remove the engine and perform an out of
chassis overhaul.
The in-chassis overhaul procedures include prescribed checks of the hardware to determine if continued in-chassis work
is practical. If the conditional limits are not met, the engine should be removed for completion of the overhaul.
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