SECTION IV. REPAIR OF ENGINE MOUNTING

TM 5-4320-258-34

Blow through the hose with compressed air to make

(5) Recheck the adjustment and, if

sure it is not clogged.

necessary, repeat until the proper closing point is

(3) Inspect the, :oil pressure safety switch

attained.

d. Installation. Installation of the oil pressure

for cracks, dents, damaged threads, and loose or

corroded electrical terminals; replace if damaged.

safety switch is the reverse of removal. Refer to items 6

(4) Inspect the hose for abrasions,

through 11 of figure 3-9. If necessary, refer to the wiring

deterioration, and damaged threads; replace a damaged

diagram (fig. 1-3) for wire connection information.

3-13. Engine Oil Pressure Adjustment

hose.

a. Description. The engine oil pressure is

(5) Inspect the remaining parts for cracks,

damaged threads, distortion, and other damage; replace

regulated by a relief valve mounted in the engine

damaged parts.

cylinder block. It consists mainly of a spring- loaded,

c. Adjustment and Testing.

spool-type valve which seats in a bore in the block. The

(1) Connect the pressure inlet of the oil

greater the spring pressure which loads the valve, the

pressure safety switch/ to an adjustable and calibrated

greater is the oil pressure in the system. The pressure

air pressure source. Connect a multimeter, adjusted

is increased by adding pressure-adjusting washers

to read continuity, across the electrical terminals.

between the spring and the valve to increase spring

(2) Under a no-pressure condition, press

force against the valve.

b. Adjustment.

and release the oil safety switch pushbutton (5, fig. 3-7)

while watching the multimeter. It must indicate no

(1) Start the engine and allow it to warm to

continuity after the safety switch pushbutton is pressed.

operating temperature. Check the engine oil pressure

(3) With the safety switch pushbutton re- leased,

indicated on the oil pressure gage. At idle speed, the

slowly apply pressure to the oil pressure safety switch

pressure must exceed 7 psi; at governed speed it must

while watching the multimeter. Continue to increase

be between 20 and 30 psi.

pressure to approximately 60 psi and then slowly

(2) If the engine oil pressure is not within

decrease pressure while noting the indication of the

the required range, shut off the engine and remove the

multimeter. As pressure is decreased to between 5 and

plug (23, fig. 4-22) from the carburetor side of the

6 psi, continuity must be made through the switch.

engine block. Remove the relieve valve spring (25) and

Continuity must be broken as the oil pressure safety

pressure adjusting washers (26).

switch pushbutton is pressed.

(3) To increase oil pressure, add a washer

(4) If the switch fails to close between 5

between the spring and valve. Not more than four

and 6 psi, turn the adjusting screw (4, fig. 3-7) on the

washers are allowed. If four washers fail to bring it into

switch to adjust the switch closing to the required level.

the required range, the spring is faulty or other engine

troubles exist.

(4) After adjustment, check that the oil

pressure remains in the required ranges during

operation.

SECTION IV. REPAIR OF ENGINE MOUNTING

3-14. Description

(1) Remove the engine from the centrifugal

pump assembly (para 2-10).

The engine is mounted on the radiator support assembly

(2) Remove the engine housing from the

at the front, and on the feet of the flywheel housing at

engine (TM 5-4320-258-12).

the rear. The resilient support at the front of the engine

(3) Remove the radiator (TM 5-4320-258--

helps cushion the engine vibration, preventing it from

12).

being transmitted to the associated equipment. The

(4) Support the engine with a hoist engaged

radiator support is connected to the flywheel housing by

in the lifting eye at the top of the engine.

adjustable tie rods.

3-15. Engine Support

(5) Remove the tie rods and related parts

a. Removal.

(items 1 through 9, fig. 3-12) that connect the radiator

support (23) with the flywheel housing

3-17