TM 5-2420-230-24-2
B3.9 and B5.9 Series Engines
Troubleshooting Symptoms Charts
Section TS - Troubleshooting Symptoms
Page TS-39
Engine Noise Excessive -- Main Bearing
This is symptom tree T050.
Cause
Correction
Check the oil pressure. Refer to the OEM
service manual. If the pressure is low, refer to
Lubricating oil pressure is below specification
.......
the Lubricating Oil Pressure Low symptom
tree.
OK
L
Check the oil level. Verify the dipstick calibra-
tion and the oil pan capacity. Fill the system to
ubricating oil level is below specification
.......
the specified level. Refer to Procedure 007-
043.
OK
L
Refer to the Lubricating Oil System - General
ubricating oil is thin or diluted
.......
Information in Section 7. Refer to the Lubricat-
ing Oil Contaminated symptom tree.
OK
M
Check the torque on the main bearing
ain bearing capscrews are loose, worn, or
capscrews. Inspect the capscrews for wear.
.......
not tightened correctly
Refer to Procedure 001-006.
OK
M
Inspect the main bearings for damage,
ain bearings are damaged or worn, or the
excessive wear, and the correct part number.
.......
wrong bearings are installed
Refer to Procedure 001-006.
OK
C
rankshaft journals are damaged or out of
Inspect the crankshaft journals. Refer to
.......
round
Procedure 001-016.
L-623
