ARMY TM 9-2815-256-24
AIR FORCE TO 38G1-96-2
MARINE CORPS TM 2815-24/5
A piston cooling orifice failure could cause damage to pistons, piston pins, rod pin bushings, and
liners. If a piston cooling orifice is left out of block during assembly, low or no oil pressure will result.
Install all the orifices and tighten to 84 in-lbs (10 Nm).
If crankshaft is to be reground, use following recommended guidelines.
Crankshaft grinding should be done only by experienced personnel on equipment capable of
maintaining crankshaft size and finish specifications.
If undersize bearings are used, check bearing clearance after bearing caps have been tightened to
specified torque. If undersize bearings are too tight and clearance is not within specifications, journal
and bearing will be wiped clean of all oil. This would result in premature wear of parts.
When grinding crankshaft, also grind fillet radii to specifications. This is necessary to prevent stress
risers in fillet areas during grinding.
In addition to standard size main and connecting rod bearings, 0.002, 0.010, 0.020, and 0.030 inch
(0.05, 0.25, 0.51, and 0.76 mm) undersize bearings are available.
The 0.002 inch (0.05 mm) undersize bearings are used normally to compensate for slight even wear
on crankshafts. Regrinding is usually unnecessary when this size bearing is used.
To maintain the correct end play, the two piece main bearing with three piece thrust washer set can
be used to replace the two piece flanged main bearings if desired.
Compare crankshaft journal measurements taken during inspection and determine size which journals are to be
If one or more main or connecting rod journals requires grinding, then grind all of main journals or all of
connecting rod journals to same required size. Grind clockwise (opposite engine rotation).
All journal fillets radii must be free of any sharp grind marks or scratches. Fillet must blend smoothly into journal
and crank cheek. Radius may be checked with a fillet gage.