TM 9-6115-604-34
NAVFAC P-8-633-34
NOTE
Plastigage is available in three clearance ranges: Type PG-1 (green) for a clearance range of
0.001 to 0.003 inch (0.025 to 0.076 mm); Type PR-1 (red) for a clearance range of 0.002 to 0.006
inch (0.051 to 0.152 mm); Type PB-1 (blue) for a clearance range of 0.004 to 0.009 inch (0.102
to 0.229 mm). Select the range needed for the clearance being checked in accordance with
Table 14.
(9)
Place a strip of Plastigage across the entire width of the bearing shell in the cap (see A, Figure 9-32).
NOTE
Before installing the main bearing capscrews (16, Figure 9-24) and washers (17), coat the
threads of the capscrews with dean engine lubricating oil, MIL-L-2104, and coat the washers
and underside of the bolt heads with SAE 140W lubricant, MIL-L-2105.
(10)
Being careful not to dislodge the Plastigage, install the bearing cap (1 8, Figure 9-24), washers (1 7), and
capscrews (16). Cross-tighten the capscrews evenly to 120 to 130 pound-feet (163 to 176 newton-meters). Tighten the
capscrews completely in accordance with Table 9-4. Do not install the main bearing sidelock capscrews (1 4) at this
time.
(11)
Remove the capscrews (16), washers (17), and main bearing cap (18), and compare the width of the Plastgage to
the graduations on the Plastgage envelope (see B, Figure 9-32). This is the main bearing journal clearance and must
conform to the specifications in Table 1-4.
(12)
If the clearance is under the specifications given in Table 1 4, remove the bearings shells (19 and 22, or 20 and 23,
Figure 9-24) and check the oversize bearing shells, or the presence of foreign matter between the bearing shells and the
cap (18) or the bearing bore in the cylinder block (58).
(13)
If the clearance is over the specifications given in Table 1-4, install new bearing shells (19 and 22, or 20 and 23)
and re-check the clearance. It the clearance is still excessive, rebuild the crankshaft in accordance with paragraph 9-28.
CAUTION
Before Installing the main bearing capscrews (16), washers (17), main bearing side-lock
capscrews (14), and lockwashers (15), coat the threads of the capscrews with clean engine
lubricating oil MIL-L-9000, and coat the washers and underside of the capscrew heads with
SAE 140W lubricant MIL-L-2105. Failure to use lubricant will result In Improper torque and
possible engine damage due to loosening of the capscrews.
(14)
If the clearance is satisfactory, remove the jack supporting the crankshaft. Remove all traces of Plastigage from
the bearing shell and crankshaft journal, lubricate the bearing shell and journal with a small amount of lubricating
oil MIL-L-2104, and reinstall the main bearing cap (18) using washers (17) and capscrews (16). Tighten the
capscrews (16) and install the side-lock capscrews (14) and lockwashers (15) as follows:
(a)
Cross-tighten the main bearing capscrews (16) evenly to 120 to 130 pound-feet (163 to 176 newton-
meters).
(b)
Install the lockwashers (15), side-lock capscrews (14), and tighten both capscrews to 5 to 10 pound-feet (7
to 14 newton-meters).
(c)
Tighten the main bearing capscrews (16) and side-lock capscrews (14) in accordance with Table 9-4.
(15)
Check to be sure that the crankshaft (32) rotates freely without binding at any point.
(16)
Replace the other main bearing shells (19, 20, 22, and 23) in accordance with steps (a) through (e), above.
9-64