( 1 0 ) Remove thrust washers from each side of
the main bearing (para 3-32).
b r a c k e t bolts to prevent valves from opening when
(11) Refer to figure 3-88 and remove and
crankshaft is rotated.
disassemble the crankshaft in numerical sequence.
(8) Remove the connecting rod bearing caps
(9) Remove the main bearing caps (para 3-
Figure 3-88. Crankshaft, disassembly and reassembly.
journals have worn out-of-round. Taper on the
c. Cleaning, Inspection and Repair.
journals of a used shaft should not exceed 0.003
( 1 ) Remove crankshaft plugs and clean out all
oil passages thoroughly,
inch, and out-of-round should not exceed 0.003
inch. The maximum taper on a new shaft is 0.0005
(2) Support crankshaft on its front and rear
inch and maximum out-of-round is 0.0025 inch.
journals in a V-block or in a lathe and check runout
o n intermediate main bearing journals, using a dial
(4) Used crankshafts will sometimes show a
i n d i c a t o r . When runout on adjacent journals is in
c e r t a i n amount of ridging caused by the groove in
o p p o s i t e direction, the sum must not exceed 0.003
the upper main bearing shell (fig. 3-89). If this
inch total indicator reading. When runout on
r i d g e is not removed before new bearing shells are
adjacent journals is in the same direction, the
installed, localized high unit pressures on the
difference must not exceed 0.003 inch total in-
bearings will result during engine operation. A
dicator reading. When high spots of runout on
ridge exceeding 0.0002 inch or more must be
a d j a c e n t journals are at right angles to each other,
removed. If ridges are greater than 0.001 inch,
t h e sum must not exceed 0.004 inch total indicator
crankshaft may have to be replaced.
r e a d i n g , or 0.002 inch on each journal. If runout
( 5 ) Check surfaces of crankshaft for evidence
l i m i t is greater than given above, crankshaft must
of cracks as follows: Several methods of deter-
mining presence of minute cracks not readily visible
to the eye are:
(3) Measure all main and connecting rod
bearing journals. Journals should be measured at
(a) M a g n e t i c P a r t i c l e M e t h o d .
several places on the circumference in order to
(b) F l u o r e s c e n t M a g n e t i c P a r t i c l e M e t h o d .
determine the smallest diameter, in case the
(c) F l u o r e s c e n t P e n e t r a n t M e t h o d .