Inspection and Reconditioning (Rev 1/97)
48
6. Use a new set of piston rings and a feeler gauge to
check the clearance between the rings and the ring
grooves. If the clearance between a new ring and its
respective ring groove is greater than the wear limit
(refer to Specifications), the piston must be replaced.
Checking Ring Clearance
7. Measure the inside diameter of the wrist pin bore. If the
inside diameter of the wrist pin bore is larger than the
wear limit (refer to Specifications), replace the piston.
Wrist Pins
The wrist pin and the connecting rod bushing carry a large
load concentrated in a small area. Therefore a precise fit is
critical. If possible, a qualified machine shop should fit new
wrist pins to new connecting rod bushings when an engine
is overhauled.
1. Measure the outside diameter of the wrist pins with a
micrometer. If a wrist pin is smaller than the wear limit
(refer to Specifications), replace the wrist pin.
2. If a micrometer with this degree of accuracy is not
available, the fit between the wrist pin and the connect-
ing rod bushing can be checked by oiling the wrist pin
and inserting it into the connecting rod bushing. The fit
should be snug and it should take a slight push to move
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the wrist pin through the connecting rod bushing, but
the wrist pin should rotate freely.
Measuring Wrist Pin
Connecting Rods
The procedures used to recondition a connecting rod, which
include honing the connecting rod bearing bore, straighten-
ing the connecting rod, and replacing the connecting rod
bushing, require various pieces of expensive equipment. If
this equipment is not available, most machine shops can
recondition serviceable connecting rods to meet standard
specifications.
1. If possible, bead blast the connecting rods with glass
beads. Bead blasting does an exceptional job of clean-
ing the rods, and it also relieves stress by removing
minor surface damage that tends to increase stress.
NOTE: Bead blasting the connecting rods is highly
recommended. Most machine shops offer this service
and the price is usually quite reasonable.
2. Check each connecting rod bearing by installing the
connecting rod cap with the bearing inserts in place and
properly torquing the rod cap bolts (refer to Specifica-
tions).
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