Reassembly and Installation. - TM-10-3930-624-340048

thickness of the compressed lead or plastic strip.

c. Reassembly and Installation.

The clearance between the shells and the journals

(1) Proceed as follows if the old main bearing

should be 0.0013 to 0.0040 inch at all main

caps are to be installed:

bearings. Install new bearing shells if this clearance

(a) Install the upper halves of the main

exceeds 0.007 inch.

bearing shells (9, fig 3-18) in the main bearing seats

(c) Measure the inside diameter of the

of the cylinder block. Make sure that the bearing

bearing cap installed and tightened to a torque of

shell tangs are properly located in corresponding

110 to 120 ft lbs. The specified inside diameter of

slots in the bearing seats of the cylinder block. The

new bearings is 2 . 5 0 0 7 - 2 . 5 0 2 4 i n c h e s . Any

flanged bearing shell is always installed at the

d e v i a t i o n b e l o w 2.5007 inches indicates the

center main bearing location.

amount of bearing wear.

(b) Lubricate all crankshaft main bearing

(d) Measure the diameter of the crankshaft

journals. Lower the crankshaft (10) into the

journal at corresponding bearing locations and

cylinder block with the flywheel flange end of the

subtract this dimension from the inside diameter

shaft toward the rear.

(c) Place the lower halves of the main

measurement of the bearing. The difference be-

bearing shells (9) in the main bearing caps (8).

tween these two measurements is the crankshaft to

inserting tangs of the shells into the slots in the

bearing clearance. The bearing shells do not form a

caps. The bearing caps are numbered one through

true circle when they are not installed. When

six, indicating their respective positions. Insert the

measuring for inside diameter, install the bearings

flanged shell in the center main bearing cap.

in the cylinder block and tighten the capscrews to

(d) Install the bearing caps (8) with the

110 to 120 ft Ibs. The two halves of the shell have a

numbers corresponding to the numbers stamped on

squeeze fit in the seat and bearing cap, and must be

the lower left side of the cylinder block, and secure

tight when the cap is drawn down.

with lockwashers (7) and capscrews (6).

(e) Check the end play of the crankshaft,

Caution: Do not overtighten the main

which is taken up by the thrust flanges of the center

hearing capscrews. Bearing caps may distort

main bearing shell. Refer to figure 3-22. The

causing bearings to be drawn tight against the

specified end play is 0.003-0.009 inch and should

crankshaft resulting in prermature failure.

not exceed 0.015 inch. If worn beyond the specified

(e) Tighten the capscrews to a torque of 110

limit, the bearing shell should be replaced.

to 120 ft Ibs.

(f) Install the flywheel and flywheel housing

(para 3-14).

(g) Install the starter motor as instructed in

TM 10-3930-624-12.

(h) Install the transmission to the engine

(para 2-9).

(i) Install the engine in the truck (para

2-10).

(j) Service the engine with lubricating oil

and coolant.

(2) Proceed as follows if new main bearing

caps are to be installed:

(a) Loosely install two 1/4 x 2 inch long

temporary locating dowels in the two inch dowel

holes in the cylinder block. Place the dowels where

the replacement cap is to be installed. Refer to

figure 3-20.

Figure 3-19. Checking crankshaft end play.

3-22