TM 9-2320-363-34-2
PISTON AND CYLINDER ASSEMBLY REPLACEMENT (CONT)
9.
10.
11.
12.
NOTE
Replace rod and main bearings whenever crankshaft is replaced or engine is
rebuilt.
Overlay plated bearings may develop very small cracks or small isolated
cavities (checking) on bearing surface during engine operation. These are
characteristics of, and are not detrimental to, this type of bearing. Bearing
should not be replaced for these minor surface imperfections.
INSPECT BEARINGS FOR SCORING, PITTING, FLAKING, CHIPPING, CRACKING, LOSS OF
OVERLAY OR SIGNS OF OVERHEATING.
IF ANY OF THESE CONDITION ARE PRESENT,
DISCARD BEARINGS.
NOTE
Upper connecting rod bearing shells will normally show signs of distress before
lower connecting rod bearing shells.
If overlay is worn to copper across
connecting rod bearing shell, replace all connecting rod bearing shells.
INSPECT BACKS OF BEARING SHELLS FOR BRIGHT SPOTS. IF SUCH SPOTS ARE PRESENT,
REPLACE BEARING SHELLS. INSPECT CONNECTING ROD BEARING BORES FOR BURRS OR
FOREIGN PARTICLES.
NOTE
Install new upper and lower connecting rod bearing shells if new crankshaft is
used.
USING MICROMETER (7) AND BALL ATTACHMENT, MEASURE THICKNESS OF CONNECTING
ROD BEARING SHELLS (8). MINIMUM THICKNESS OF WORN STANDARD CONNECTING ROD
BEARING SHELL SHOULD NOT BE LESS THAN 0.1215 IN. (3.086 mm). IF EITHER UPPER OR
LOWER CONNECTING ROD BEARING SHELL (8) OF CONNECTING ROD SET IS LESS THAN
MINIMUM THICKNESS, REPLACE
EXAMINE CYLINDER LINER FOR
CAVITATION EROSION. IF ANY
DISCARDED.
12-152
BOTH BEARING SHELLS (8).
CRACKS, SCORING, GLAZING, RING RIDGE FORMATION, AND
OF THESE CONDITIONS ARE PRESENT, LINER MUST BE
