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TM5-4210-229-14&P
6-13. FLYWHEEL, CRANKSHAFT, AND MAIN BEARING MAINTENANCE (Continued).
(3) For old bearings and caps, if the crankshaft,
bearings and crankcase are in good condi-
tion, the bearing running clearance should
fall within Q.0018 to 0.0051 in. (0.046 to
0.130 mm).
(a) If the clearance obtained is more or less
than the specified amount, replace with
a new bearing.
(b) Should the clearance remain excessive,
it may be necessary to replace the
crankshaft.
(4) New bearings and caps installation.
(a) Measure the diameter of the crank-
shaft journal and record this reading. If
it is less than 3.3742 to 3.3755 in.
(85.705 to 85.738 mm), subtract the
difference from the virgin lead or plas-
tigage reading.
(b) Subtract the bearing running clearance
of 0.0018 to 0.0051 in. (0.046 to
0.130 mm) from the measurement ob-
tained in step 4a. Mill or grind this
amount from surface of the new bearing
cap.
(c) Recheck the bearing running clear-
ance, with virgin lead or plastigage, to
assure 0.0018 to 0.0051 in. (0.046 to
0.130 mm) specifications are met.
(5) Remove the plastigage or virgin lead.
(6) Add clean oil (Appendix D, Item 37) to the
bearing and install the center main bear-
ing cap.
(7) Torque the cap screws to 115 ft-lb
(155 N.m).
(8) Check each main bearing in the same man-
ner described above, steps (1) through
(7).
d. Crankshaft end clearance check.
(1) Loosen the rear main bearing cap screws.
(2) Hold the crankshaft towards the front of the
engine, using a suitable bar or large screw-
driver, so the crankshaft thrust surface is
tight against the rear of the thrust flange of
the bearing in the crankcase.
(3) Check the clearance across the bearing split.
0.006 to 0.012 in. (0.15 to 0.30 mm) clear-
ance must be maintained.
(4) Hold the crankshaft towards the rear of the
engine and check the clearance across the
bearing split. If the clearance is more than
specified, replace the rear main bearing
with a new one.
(5) With the feeler gauge in place, torque the
rear main bearing cap to 115 ft-lb (155 N.m)
torque.
(6) Remove the feeler gauge and wedging tool.
(7) Pull the connecting rods down onto the
crankshaft. Be sure that the bearings are
in place.
(a) Install the connecting rod bearings and
bearing caps. Make sure that the cor-
rect cap is located on its rod and that
the identifying numbers are on the in-
take manifold side of the engine.
(b) Oil the bearings with clean engine oil
(Appendix D, Item 37).
(c) Torque the connecting rod bolts to
130 ft-lb (175 N.m).
e. Ring gear replacement.
(1) Remove the ring gear from the flywheel by
heating the gear with a torch to expand it.
Then drive gear from the flywheel.
6-41
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