Crankshaft and Bearings - TM-10-3930-627-340040

(6) Connecting rods are numbered according to

(main) bearings can be replaced without removing the

cylinder bore in which they must be installed. Number

engine, if shaft does not have to be removed. However,

one cylinder is at the fan end of the engine. Oil squirt

it is usually recommended seals and gaskets be

hole in rod should be installed toward camshaft side of

replaced at this time (which would require engine

engine. Crankshaft journal should be at bottom dead

removal) if engine has had long service without major

center of cylinder bore in which piston and rod is being

maintenance. In this case remove engine first to make

installed. Use a hammer handle to force piston through

entire job easier.

compressor into cylinder bore. While forcing piston into

(1) Remove the oil pump. (para 3-10.)

bore, ring compressor must be kept tight against

(2) Mark the bearing caps (13, 14, and 15, fig. 3-

cylinder block to prevent damage to piston rings as they

4) for correct installation.

These caps are not

enter bore.

interchangeable, nor are they to be reversed side for

(7) Apply a light coat of oil to connecting rod

side at installation.

bearing cap and install lower half of the connecting rod

Note.

bearing in cap, making certain that bearing lock fits in

To keep crankshaft supported, if

machined notch of rod. Apply a light coat of oil to

engine is not removed, one pair of

bearing and install bearing cap and bearing on

bearings should be replaced at a

connecting rod. Tighten nuts to 35 to 40 foot-pounds

time, leaving bearing cap screws

torque. Install cotter pins in nuts.

snug but not tight when installing

(8) Complete installation of pistons.

Before

until all bearings are replaced.

replacing the engine head, squirt a few drops of oil

(3) Remove safety wire from main bearing cap

around edges of pistons to help lubricate rings when

screws and remove cap screws and caps from engine

starting engine.

block.

(9) Complete installation by reversing removal

(4) Remove bearing halves (10, 11 and 12) from

procedure.

caps.

(5) Insert bearing removing tool or flat head rivet,

with head thickness less than that of bearing shell, into

oil hole in the crankshaft journal. Rotate crankshaft so

that tool or rivet forces upper bearing half out of engine

block. Make certain to rotate crankshaft in proper

direction so that bearing lock is pushed out of notch in

engine block.

(6) Coat new bearing half with engine oil and

insert in same manner as old bearing half was removed.

(7) Coat lower bearing half with engine oil and

insert in bearing cap.

(8) Install bearing cap following procedure in step

b. below to check clearances. After clearance is

checked, leave cap screws loose so other bearings may

be accurately checked.

(9) Replace remaining bearings in same manner.

Note.

Be sure thrust side of center

(flanged) main bearing lower half is

flush with thrust side of upper half,

then check crankshaft end play (fig.

3-18). End play should be 0.002 to

0.006 inch.

(10) Torque main bearing cap screws to 85 to 95

foot-pounds. Safety wire front and rear main bearing

cap screws.

(11) Mount oil pump to block. (para 3-10c.)

Figure 3-17. Installing pistons with ring compressor.

(12) Safety wire center main bearing cap screws

after pump installation.

3-13. Crankshaft and Bearings

(13) Install oil pan and seals (para 3-9).

a. Replacement of Crankshaft Bearings. Crankshaft

3-13