a. Remove valve cover, rocker arm and shaft
e. Examine piston pins for wear, corrosion, or
assembly, and pushrods. Remove valve lifters, pan, oil
etching, and replace if any of these are evident. f.
pump and gear cover. Remove capscrews (1), and
Inspect connecting rods and rod bushings for wear,
remove camshaft assembly.
cracks, pits, etc.
b. With both heads removed, rotate the shaft
g. Align connecting rods using a connecting rod
position the journals for removal of the rods.
mandrel. Place the rod flat in the mandrel to check for
any malformation by inserting feeler gages between the
Note. Remove the ridge from the top of the cylinder
rod and mandrel. A malformation of 004 inch or greater
block Mark all pistons, rods and bearing caps for
is cause for rejecting the rod.
replacement in same cylinder bore.
h. Inspect the crankshaft for cracked, scored,
c. Remove rod bolts (2), rod caps (3), and rod
grooved or worn main bearing journals. If the journals
bearing half (4). Push pistons and rod assemblies
show wear or out of round in excess of 002 inch, the
through the top of the block.
crankshaft should be reground and undersize bearing
d. Remove main bearing bolts (5), washer (C and
installed or replaced. Refer to table 1-4 for journal
bearing caps (7, 8, and 91.
e. Lift crankshaft straight up and out of engine
i. Examine crankshaft timing gear teeth and
13-34. Disassembly
replace the gear if the teeth are worn or damaged.
Refer to figure 13-6 and disassemble camshaft pistons,
Note. The crankshaft gear and the timing gear on the
and crankshaft as follows.
camshaft are matched sets. When one is replaced, both
a. Remove jam nut (10), distributor gear (1)fuel
must be replaced.
pump cam (12), and gear (13). Remove (14) and thrust
j. Inspect crankshaft bearing for wear and
plate (15).
evidence of uneven bearing support. If such evidence is
b. Using a piston ring expander, remove piston ring
present, examine the bearing caps for high spots or
set (17). Remove top ring first and remaining rings in
order.
burrs. 13-37. Repair and Replacement
c. Heat piston (18) in boiling water or a piston
a. Refer to TM 5-3810-294-34P for repair parts.
heater. Position the piston and rod assembly in piston
b. Replace all worn or chipped gears. Replace
vise and remove the piston pin retainers and drive pin
camshaft if lobes are cracked, worn, pitted, etc. c.
(20) from the bore. Press bearings (21) from rod (3).
Replace all bearings that reveal badly worn or scored
d. Using a gear puller, remove crankshaft (22).
areas. Check all parts against values shown in table 1-4.
Remove key (23) and bearing set (24 and 25), and seal
13-38. Reassembly and Installation
(26) from crankshaft (27).
Refer to figure 13-6 and assemble and install camshaft,
13-35. Cleaning
pistons and crankshaft as follows.
a. Clean all metal parts in dry cleaning solvent
a. Turn the block on the stand so that the bottom
(Federal
Specification
P-S-661)
and thoroughly.
faces upward. Position the rear main bearing upper seal
Remove all carbon and corrosion from engine parts.
(26) in the groove in the block.
Clean remaining gasket material from engine parts.
b. Install key (23) in crankshaft (27). Press gear
b. Clean bearings carefully in solvent and allow to
(22) onto crankshaft.
dry. Do not use compressed air to dry bearings Coat
c. Lubricate the block half of bearings (24 and 25).
bearings in engine oil immediately after drying. Clean all
Place the bearing shell halves in the bore of the block.
oil holes and passages with brass probes.
Be sure that the oil holes in bearing shells line up with
c. Clean piston and piston pins in clean solvent.
the oil holes in the block, and that the locking tangs on
the bearings fit into the recesses. Follow the same
Note. Do not use a caustic solvent for cleaning
procedure and place the bearing shell halves in the
aluminum pistons.
bearing caps (7 and 8).
13-36. Inspection
d. Place crankshaft into crankcase. Install oil seal
a. Inspect camshaft journal for evidence of wear or
(2'6) into the recesses of the rear main bearing cap. The
out of round. Refer to table 1-4 for wear limits
overhanging lip on the front of this seal must be toward
b. Check the oil pump drive gear on the rear of the
the rear of the engine.
camshaft. If teeth are worn or damaged, camshaft must
Note. The words "left" and "right " are stamped on the
be replaced because the gear is integral with the shaft.
feet of the seals, and the foot of the right seal is yellow.
c. Inspect camshaft lobes.
Inspect camshaft
The
bearings for wear and proper running clearance.
d. Inspect piston for scuffed, marred, or scored
skirts and cracked or worn piston ring lands.
13-9
