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TM 5-4320-306-24
4-13.
REPLACE/REPAIR CRANKCASE ASSEMBLY (Continued)
24
Inspect and replace stop rings for excessive wear, cracks, warpage, rust, corrosion, or other damage Measure
thickness, which should be 0.1156 to 0.1175 inch (2.935 to 2.985 mm). If measurement is not within tolerance
limits, replace stop ring.
25
Inspect dowel bushings and screw plugs and replace if excessively worn, warped, rusted, corroded, or otherwise
damaged.
REPAIR.
1
Replace crankcase if:
a.
Crankcase is cracked, overheated, distorted, or seriously damaged.
b.
Crankcase machined surfaces are severely rusted or corroded.
c.
New main bearing bushing or camshaft bushing will not seat properly in crankcase.
d.
Crankcase bore for main bearing bushing or camshaft bushing is outside tolerance limits.
e.
Cylinder seats are worn, not flat, or damaged beyond repair.
f.
Tapholes, tappet bores, dished plug bore, parallel pin, or screw plug holes are excessively worn, cracked,
or damaged beyond repair.
2
Repair minor rust, corrosion, nicks, or burrs on crankcase. Use crocus cloth to smooth out surfaces if necessary.
Clean and refinish nonmachined surfaces. Allow finish to dry. Do not finish machined surfaces. Rebore tappet
bores if necessary. Retap tapholes if necessary.
3
Do not attempt to rebore or otherwise repair any crankcase bearing bores. If bushings or ball bearings do not fit
tightly into bore, replace crankcase.
4
Repair minor nicks, burrs, rust, or corrosion on cylinder seats with crocus cloth. Do not refinish. If seats need to
be refaced smooth or flat, use crankcase cylinder seat refacing tool No 150020.
4-113
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