Crankshaft and Main Bearings

(6) Rotate the crankshaft to place the piston

( 3 ) Carefully lower the liner into the cylinder

t o be removed at top dead center. Push the con-

b l o c k . Drive into place until the liner bottoms.

necting rod upward until the piston rings are out of

NOTE

the cylinder. Lift out the piston and connecting rod

assembly.

( 7 ) Remove the piston pin retaining rings (6)

from the piston pin (7) and press out the piston pin.

(4) Press the bearing (10) into place in the

connecting rod (8). Secure the piston (9) to the

Separate the connecting rod (8) from the piston (9).

connecting rod using the piston pin (7). Install the

R e m o v e the bearing (10) from the connecting rod

r e t a i n i n g rings (6).

( 8 ) if replacement is necessary.

( 5 ) Using a piston ring expander, install the

( 8 ) Using a piston ring expander, remove the

piston rings (11 and 12) in their grooves. Install the

piston rings (11 and 12) from the piston (9).

middle ring with the "top" mark up.

CAUTION

( 6 ) Oil the piston and rings. Place the piston

Cover the crankshaft and main hearings

a n d connecting rod assembly in the cylinder liner.

before removing the sleeves. Sediment

Use a piston ring compressor to aid in installation.

from the block could damage the

Position the V-mark on top of the piston so that it is

crankshaft and bearings.

aligned with the V-mark on the block.

(9) Using a liner puller assembly and an

( 7 ) Install the bearing upper half (5), bearing

adapter plate, remove the liner (13) from the block

lower half (3) and cap (2). Secure with bolt (4) and

(15). Discard the rings (14).

n u t (1). Lubricate the threads with crankcase oil

b. Cleaning. Clean

all

components

except

and tighten to a torque of 27 to 33 foot-pounds.

p i s t o n s with cleaning solvent (Fed. Spec. P-D-680)

Then tighten an additional 85 to 95 degrees.

and dry with clean, lint-free cloths. Remove carbon

(8) Install the cylinder block inspection covers

d e p o s i t s from pistons with fresh, cold water. Soak

o r the oil pan, if removed.

t h e pistons in water overnight and allow to dry in

( 9 ) Install the cylinder head and valves (para

s u n l i g h t . Ensure that ring grooves are clean.

5-27).

c. Inspection and Repair.

(10) Service the engine lubricating system and

( 1 ) Inspect connecting rod bearings for burrs

cooling system. Refer to TM 5-2410-233-10.

a n d rough spots. Light scratching will not impair

operation. Smooth minor roughness with a soft

5-34.

Crankshaft

and

Main

Bearings

h o n e or crocus cloth. Replace very rough bearings.

a. Remoual and Disassembly.

If one bearing must be replaced, replace all

( 1 ) Remove the engine from the tractor. Refer

bearings

possible.

to paragraph 2-8. Place the engine on a suitable

(2) Replace bent connecting

rods.

work stand.

(3)

Press the piston pin into

position into the

(2) Remove the water pump (para 5-6).

bearing. Measure the clearance.

Replace the pin

R e m o v e the timing gear cover (para 5-29) and the

and bearing if clearance exceeds

0.004 inch.

flywheel and housing (para 5-32).

(4) Inspect tbe piston pin for cracks, score

(3) Place the engine on its side and remove the

m a r k s or pitting. Discard the pin if surfaces are

o i l pan and oil pan plate (para 5-25) and the oil

dull, rough or checked by acid corrosion.

pump (para 5-24).

(5) Inspect the bearing liners for wear,

(4) Remove the connecting rod bearings and

scratches, p i t t i n g a n d m e t a l f a i l u r e . R e p l a c e a s

caps (para 5-33). Push the piston and rod

required.

a s s e m b l i e s upward into the cylinders to clear the

(6) Inspect the piston for grooves, scoring,

crankshaft.

pitting and other damage and for wear. Replace

(5) Wrap a heavy cloth around the number

two and five connecting rod bearing sufaces on the

p i s t o n if surface damage is excessive.

( 7 ) Inspect the cylinder sleeve for scratches,

crankshaft.

scoring, grooving and wear. Measure the inside

( 6 ) Place a cable around the cloth and attach

a hoist to the cable. Tighten the cable just enough

d i a m e t e r using a micrometer. Replace the sleeve if

to prevent the crankshaft from moving when the

diameter exceeds 4.758 inch at any point.

main bearing caps are removed.

d. Reassembly and Installation (fig. 5-56).

( 1 ) Ensure that the engine block is clean.

( 7 ) Remove the bolts and washers that secure

(2) Install new rings (14) on the cylinder liner

the bearing caps to the block. Refer to figure 5-57.

(13).

5-77