TM 5-3805-260-24
CLEANING AND INSPECTION
OF PARTS
CLEANING
All parts should be cleaned thoroughly in a good cleaning
solvent before inspection.
CYLINDER HEAD ASSEMBLY
Remove all carbon deposits from discharge cavities and
all rust and scale from cooling cavities of cylinder head
body. Scrape all foreign matter from body surfaces and
use air
pressure to blow dirt particles from all cavities.
Discharge valves can be dressed by lapping them on a
piece
of fine crocus cloth on a flat surface, provided they are
not excessively worn.
CYLINDER BLOCK
Clean carbon and dirt from inlet and unloader passages.
Use air pressure to blow carbon and dirt deposits from
unloader passages.
Inlet valves, as in the case of discharge valves, not
worn excessively, can be cleaned by lapping them on a
piece of fine crocus cloth on a flat surface.
OIL PASSAGE
Clean thoroughly all oil passages through crankshaft,
connecting rods, crankcase and end covers. If
necessary inspect passages with a wire and blow foreign
matter out with air pressure.
INSPECTION OF PARTS
CYLINDER HEAD BODY
Inspect cylinder head body for cracks or damage.
DISCHARGE VALVES AND SEATS
If discharge valves are worn and grooved where they
contact the seats, they should be replaced. If the
discharge valve seats are worn excessively so that there
is no longer enough metal left to reclaim them by
lapping, the seats should be replaced.
DISCHARGE VALVE SPRING AND CAP NUTS
Replace all used discharge valve springs and cap nuts.
CRANKCASE AND END COVERS
Check for cracks or broken lugs in crankcase and end
covers. Also check their oil passages to make sure they
are
open
and
clean
Check the crankshaft sleeve bearing in the rear end
cover for excessive wear and flat spots and replace if
necessary.
CYLINDER BLOCK
Check for cracks or broken lugs on cylinder block. Also
check unloader bore bushings to be sure they are not
worn, rusted or damaged. If these bushings are to be
replaced they can be removed by running a 1/8 in. pipe
thread tap inside the bushing, then inserting a 1/8 in.
pipe threaded rod and pulling the bushing straight up and
out. Do not use an easy-out for removing these
bushings.
INLET VALVES AND SEATS
If inlet valves are grooved or worn where they contact the
seat, they should be replaced. If the inlet valve seats
are worn or damaged so they cannot be reclaimed by
facing, they should be replaced.
MEASURING CYLINDER BORES
CYLINDER BORES
Cylinder bores which are scored or out of round by more
than 0. 002 in. or tapered more than 0. 003 in. should
be rebored or honed oversize. Oversize pistons are
available in 0. 010, 0. 020, and 0. 030 oversizes.
Cylinder bores must be smooth, straight, and round.
Clearance between cast iron pistons and cylinder bores
should be between 0. 002 in. minimum and 0. 004 in.
maximum (Fig. 20).
3-19
