TM 9-2320-302-34
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CRANKSHAFT REPLACEMENT - CONTINUED
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INSPECTION
CAUTION
Vibration damper must be replaced at normal engine overhaul or if crankshaft breakage is experienced. Fail-
ure to do so could result in premature crankshaft failure.
NOTE
•
Crankshaft failures are rare. When crankshaft cracks or breaks completely, thoroughly inspect for con-
tributory factors. Unless abnormal conditions are discovered and corrected, crankshaft failure will be
repeated.
•
Ensure all main bearing saddles and thrust bearing counterbores in cylinder block are clean.
•
Each upper main bearing shell is grooved with oil hole. Register oil hole in each upper main bearing
shell with oil hole in each main bearing saddle of cylinder block.
•
Install main bearings in sets only. Do not mix old and new main bearing shells on same journal. If old
bearings are installed, they must be installed in same journal they were removed from.
1.
Inspect crankshaft timing gear keyway for evidence of cracks or wear. Replace crankshaft if damage is evident.
2.
Inspect crankshaft for evidence of overheating. Replace crankshaft if damage is evident.
3.
Check crankshaft journal surfaces for score marks or imperfections. If excessively scored, replace crankshaft.
4.
Check crankshaft thrust surfaces for excessive wear or grooving. If excessively worn, replace crankshaft.
5.
Check crankshaft timing gear for worn or chipped teeth. Inspect timing wheel for bent or damaged teeth. Replace as
necessary.
6.
Support crankshaft front and rear journals on V-blocks or inverted engine block with only front and rear upper bearing
shells in place. Check intermediate main journals with dial indicator for runout when crankshaft is rotated. Replace
crankshaft if runout is greater than maximum shown in Table 1.
Table 1. Intermediate Main Journals Runout.
7.
Measure all main bearing journals (19) and connecting rod bearing journals (20), as shown, at several places on circum-
ference to determine taper, out-of-round, and journal diameter. Replace crankshaft if not within specifications shown.
JOURNAL SUPPORTED ON
JOURNALS MEASURED
MAXIMUM RUNOUT:
TOTAL INDICATOR
READING
No. 1 and No. 7
No. 2
0.0030 in (0.076 mm)
No 1 and No. 7
No. 3
0.0051 in (0.130 mm)
No. 1 and No. 7
No. 4
0.0060 in (0.152 mm)
No. 1 and No. 7
No. 5
0.0051 in (0.130 mm)
No. 1 and No. 7
No. 6
0.0030 in (0.076 mm)
