Specifications

7
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plugged, and check for leakage by applying a soap solution
to the exterior of the body. If leakage is detected, replace
the head.
END COVERS
Check for cracks and external damage. If the crankshaft
main bearings are installed in the end cover, check for
excessive wear and flat spots and replace them if necessary.
If the compressor has an oil seal in the end cover, it should
be removed by pressing it out of the end cover.
CRANKCASE
Check all crankcase surfaces for cracks and damage. On
compressors where ball bearing main bearings are used the
difference between the O.D. of the outer race and the I.D. Of
the crankcase hole should be .0000 in. to .0015 in. loose.
This is to maintain the correct press fit. The crankcase must
be replaced if the fit is too loose.
On compressors fitted with precision, sleeve main bearings,
the difference between the O.D. of the crankshaft journal
and the main bearing I.D. must not exceed .0065 in. If the
clearance is greater than .0065 in., the end cover or main
bearing must be replaced.
CYLINDER BLOCK
Check the 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 into the bushing, and 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. If the inlet
valve seats are worn or damaged, so they cannot be
reclaimed by facing, they should be replaced. Cylinder bores
should be checked with inside micrometers or calipers (see
Figure 8). Cylinder bores which are scored or out of round
by more than .001 in. or tapered more than .002 in. should
be rebored or honed oversize. Oversized pistons and piston
rings are available in .010 in., .020 in. and .030 in. oversizes.
Cylinder bores must be smooth, straight, and round.
Clearance between the cast iron pistons and cylinder bores
should be between .002 in. minimum and .004 in. maximum.
PISTONS
Check the pistons for scores, cracks, or enlarged ring
grooves; replace the pistons if any of these conditions are
found. Measure each piston with a micrometer in relation to
the cylinder bore diameter to be sure the diametral clearance
is between .002 in. minimum and .004 in. maximum.
Check the fit of the wrist pins to the pistons and connecting
rod bushings. The wrist pin should be a light press fit in the
piston. If the wrist pin is a loose fit, the piston and pin
assembly should be replaced. Check the fit of the wrist pin
in the connecting rod bushing by rocking the piston. This
clearance should not exceed .0007 in. Replace the wrist pin
bushings if excessive clearance is found. Wrist pin bushings
should be reamed to between .5314 in. and .5317 in. after
being pressed into the connecting rods.
Check the fit of the piston rings in the piston ring grooves.
Check the ring gap with the rings installed in the cylinder
bores. Refer to Figure 9 for correct gap and groove
clearances.
FIGURE 8 - MEASURING CYLINDER BORES
FIGURE 9 - CORRECT GROOVE CLEARANCE
.002"
.010"
END GAP
.000
.006
OIL RING
.002
.004
OIL RING
STANDARD
PISTON
RING
OIL RING
PISTON
RINGS
PISTON
RING
EXPANDER
RING