Camshaft, Balance Shaft and Bearings

TM 10-3930-242-34

(2) To permit cleaning out any foreign mat-

oil seal spacers; then, slide them on the shaft.

e r i a l that may be lodged at the ends of the oil

(4) Install a woodruff key in each shaft.

p a s s a g e , remove the end plugs from the cam-

( 5 ) Install pulleys on the shaft.

s h a f t as follows:

( 6 ) Install and tighten pulley retaining nuts

(a) Clamp the camshaft in a vise equipped

to 300-325 foot-pounds torque.

w i t h soft jaws. Use care to prevent damage to

(7) Install various parts and assemblies

t h e cam lobes and machined surfaces of the

p r e v i o u s l y removed as outlined in their respec-

shaft.

t i v e paragraphs of the manual.

(b) Make an indentation in the center of

3-29. Camshaft, Balance Shaft and Bearings

one of the end plugs with a 31/64-inch carboloy tip

a. General. The camshaft, balance shaft and

drill.

b e a r i n g s are located just below the top of the

( c ) To aid in breaking through the har-

c y l i n d e r block. The camshaft and balance shaft

dened surface of the plug, punch a hole as

a r e described in paragraph 3-27.

d e e p l y as possible with a center punch.

b. Removal of Camshaft or Balance Shaft,

(d) Then, use a 1/4-inch carboloy tip drill to

drill a hole through the center of the plug.

NOTE

(e) Redrill the end plug with a 5/16-inch

Whenever an engine is being completely

recon-

carboloy tip drill.

d i t i o n e d or the bearings, thrust washers,

or the

g e a r s on the shafts need replacing, the

shafts

(f) T h r e a d t h e h o l e i n t h e p l u g w i t h a

should be removed from the engine in the

follow-

3/8-inch-16 tap.

i n g manner:

(g) Remove the end plug from the cam-

(1) Drain the engine cooling system.

shaft.

( 2 ) Remove the engine (para 2-5) and at-

(h) Insert a 3/8-inch steel rod in the cam-

taching parts necessary to mount engine on

s h a f t oil gallery and drive the remaining plug

overhaul stand.

out. If a steel rod is not available perform steps

( 3 ) Mount the engine on an overhaul stand.

( a ) through (g) above to remove the remaining

B e sure the engine is securely mounted on the

plug.

s t a n d before releasing the lifting sling.

d . Cleaning, Inspection, and Repair.

(4) Remove the cylinder head (para 3-19).

(1) Clean all parts thoroughly, using sol-

( 5 ) Remove the flywheel and the flywheel

vent P-D-680, or equal. Be sure the oil holes in

housing (para 3-21 and 3-22),

the camshaft(s) are clean. Sludge accumula-

( 6 ) Remove the bolts which secure the gear

tions, which might restrict the oil flow, must be

n u t retainer plates (if used) to the gears; then

removed.

r e m o v e the retainer plates.

( 2 ) Inspect the cams and journals, and, if

(7) Wedge a clean rag between the gears as

they are badly scored or worn, replace the cam-

shown in figure 3-54; then, remove the nuts

shaft.

from each end of both shafts with a socket

( 3 ) If cams are scored, the cam followers

wrench.

s h o u l d also be inspected para 3-15).

(4) Examine both faces of the thrust

( 8 ) Remove the balance weights from the

washers. If either face is scored or if the thrust

front end of the shafts (fig. 3-55).

washers are worn excessively, replace the

( 9 ) Remove the upper engine front cover

w a s h e r s . New thrust washers are 0.208-0.210

(para 3-28).

inch thick.

( 1 0 ) Remove the oil slinger from the front

( 5 ) Also, examine surfaces which the thrust

end of both shafts.

w a s h e r s contact; if these surfaces are scratched

(11) Remove the two thrust washer retain.

b u t not severely scored, they may be smoothed

i n g bolts that secure the camshaft or balance

down with an oil stone. However, if score marks

s h a f t thrust washer to the cylinder block, by

are too deep to be removed, or if parts are badly

i n s e r t i n g a socket wrench through a hole in the

w o r n , new parts must be used.

web of the gear,

( 6 ) The clearance between new shafts and

( 1 2 ) Withdraw the shaft, thrust washer, and

new bearings is from 0.0045-0.006 inch or a max-

g e a r , as an assembly, from the rear end of the

i m u m of 0.008 inch with worn parts. Excessive

c y l i n d e r block.

c l e a r a n c e between the shafts and the bearings

w i l l cause low oil pressure and excessive back-

c. Disassemble Camshaft or Balance Shaft.

l a s h between the gears.

(1) Refer to figure 3-55 and disassemble the

e. Remove Bearings.

c a m and balance shaft.

3-65