Section IV. REPAIR OF THE ENGINE COMPONENTS

Section IV. REPAIR OF THE ENGINE COMPONENTS

3-12. C y l i n d e r H e a d , V a l v e s a n d V a l v e

3-11. General

Mechanism

The removable valve-in-head cylinder head is

a. Removal.

attached to the cylinder block by special capscrews.

It contains the intake valves, exhaust valves, in-

(1) Remove the hood, side panels, seat and

seat support, and air cleaner. Refer to TM 10.

serts, and spark plugs and supports the rocker arm

3930-624-12.

assembly, The one piece cylinder block employs

(2) Remove the rocker arm cover (4, fig. 3-7).

replaceable cylinder sleeves which are sealed in the

Remove the vent hose.

block base by seal rings. The top of the cylinder

(3) Remove the oil tube from the cylinder

sleeves are flanged to fit a machined recess in the

cylinder block. A one piece head gasket prevents

head to the rocker arm shaft.

(4) Remove the capscrews (6) and washers

leakage between the block, cylinder sleeves, and

(7) which secure the rocker arm shaft supports (9)

cylinder head. The crankshaft is a heat-treated

and clips (8) to the cylinder head. Lift the rocker

alloy steel forging, s u p p o r t e d b y s e v e n m a i n

arm assembly from the head.

bearings. The crankshaft has an oil seal at each

(5) Drain the radiator and engine block.

end. The aluminum pistons are attached to the

Refer to TM 10-3930-624-12.

forged steel connecting rods by full-floating piston

(6) Remove the intake and exhaust manifold.

pins. The pins are secured in the piston by snap

Refer to TM 10-3930-624-12.

rings in the piston bosses. The connecting rods

(7) Disconnect the lead from the coolant

utilize bronze bushings in the upper end and

temperature sending unit. Remove the coolant

replaceable, steel-backed aluminum lined bearings

tubes and the thermostat housing. Refer to TM 10-

in the lower end. The camshaft, supported by four

3930-624-12.

camshaft bearings, is driven from the crankshaft

(8) Disconnect the rocker arm oil feed line

gear through the timing gear and operates the

from the cylinder head and move it out of the way.

valves through the push rods and rocker arm

assembly. The camshaft also drives the oil pump,

(9) Remove the cylinder head capscrews and

fuel pump, and distributor. The rocker arms are

washers. Attach a hoist to the cylinder head and

installed on a hollow shaft which provides

remove from the truck. Discard the head gasket.

lubrication for the rocker arms. Excess oil flows out

b. Disassembly. (fig. 3-7.)

(1) Slide the rocker arms (10 and 11) off the

through an overflow line and lubricates the valve

rocker arm shaft (12). Remove the adjusting screws

lifters and the camshaft. The intake and exhaust

(13) and plug (14).

manifold is a one piece casting with separate

porting for the exhaust gases and incoming fuel-air

mixture. An updraft carburetor is mounted on the

intake manifold.

3-9