(8) To remove the upper main bearings (8, 9)
removal is necessary, properly support the
without removing the crankshaft (12),
crankshaft (12) and gear in an arbor press
insert a small tee-shaped pin in the
and remove the gear (10) from the
crankshaft oil hole. Rotate the crankshaft
crankshaft (12). Remove the woodruff key
(12) so that the pin will push the upper
(11). If the gear must be replaced and an
arbor press is not available, use a 1/4-inch
If the crankshaft is to be removed, remove
(6.35 mm) drill centered midway between
the upper bearings after removing the
the edge of the keyway and the base of
the gear teeth and drill through the gear
parallel with the keyway. Spread the gear
with a chisel and pull from the shaft. Be
careful not to drill into the crankshaft.
(5) Inspect the bearing caps (3, 4, 5, 6) for
cracks and distortion.
(6) Inspect the main bearings (7, 8, 9) for
scoring, chipping, flaking, pits, and signs
of overheating. Bright spots on back of
bearings indicate shifting and are cause
Replace all main
bearings if one or more is damaged and
(7) Inspect the crankshaft (12) for cracks,
scored journals, and misalignment.
Replace if damaged beyond repair.
Perform detailed inspection of the
crankshaft as follows:
crankshaft for cracks. There are
several methods of determining the
presence of minute cracks not
Figure 7-61. Upper main bearings,
visible to the eye. These inspection
removal and installation.
methods include magnetic particles,
fluorescent magnetic particles, and
(9) Remove the connecting rod bearing caps
circumferential fillet cracks at the
(10) Use a rope sling and a hoist to remove the
critical areas, and 45 cracks (45
with axis of the shaft) starting from
Take care to prevent
either the critical fillet locations or
scoring of the crankshaft journals.
the crankshaft holes. Cracks of this
(11) Remove the upper main bearin gs (8, 9)
nature require replacement of the
from the cylinder block.
(b) Inspect the keyways for cracks, or
b. Cleaning, Inspection, and Repair.
wear; replace the shaft if necessary.
(c) If the crankshaft is worn so that the
(1) Discard and replace all gaskets and seals.
(2) Clean all parts in accordance with para
clearance (with new bearings)
exceeds 0.007 inch (0.178 mm), or
(3) Clean the oil passages in the crankshaft
the maximum taper is 0.0015 inch
(0.038 mm), or the out-of-round is
(4) Inspect the crankshaft gear (10) for
0.002 inch (0.051 mm), the
cracked or worn gear teeth.