DETROIT DIESEL 53
Piston and Piston Rings
1.6
Other factors that contribute to piston failure are oil
Clean the inside surfaces of the piston and the oil return
leaks into the air box, oil pull-over from the air cleaner,
holes in the piston skirt. Exercise care to avoid
dribbling injectors, combustion blow-by and dilution of
enlarging the holes while cleaning them.
the lubricating oil.
Inspection
Inspect and measure the piston pin and piston pin
bushings. The piston pin-to-bushing clearance with new
The presence of the tin coating on the piston and the
parts is .0025" to .0034". A maximum clearance of
original grooves in the piston rings indicates very little
.010" is allowable with worn parts. The piston pin
wear.
bushings in the connecting rod are covered in Section
1.6.1.
An excessively worn or scored piston, rings or cylinder
liner may be the result of abnormal maintenance or
Remove Bushings from Piston
operating conditions which should be corrected to avoid
recurrence of the failure. Proper maintenance of the
1. Place the piston in the holding fixture J 1513-1 so
lubricating oil filters and air cleaners will reduce to a
that the bushing bores are in alignment with the hole in
minimum the amount of abrasive dust and foreign
the fixture base.
material introduced into the cylinders and will, in turn,
reduce the rate of wear. Extended periods of operation
2. Drive each bushing from the piston with the bushing
at idle speed or the use of improper lubricating oil or fuel
remover J 49724 and handle J 1513-2 in the manner
should be avoided, otherwise heavy carbon formation
illustrated in Fig. 5.
and sticking rings will result. Always maintain the
lubricating oil and engine coolant at the specified levels
Install Bushings in Piston
to avoid overheating the engine.
1. Place the spacer J 7587-1 in the counterbore in the
Examine the piston for scoring, overheating, cracks and
fixture J 1513-1 (small end up).
damaged ring grooves.
Replace the piston, if
necessary. A piston with light score marks may be
cleaned up and reused. Refer to Fig. 4 for a
comparison of pistons.
Check for cracks across the struts in the piston as
outlined in Section 1.3 under Crankshaft Inspection.
Fig. 4. - Comparison of Pistons
1972 General Motors Corp..
February, 1972
SEC. 1.6 Page 3
