SECTION II. REPAIR OF COOLING SYSTEM COMPONENTS

TM 5-4320-258-34

cup from the governor arm and carefully remove all

distortion, damaged threads, and other damage; replace

grease from the cup and from the interior of the arm.

damaged parts.

d. Reassembly and Installation.

(3) Remove all grease from the toothed

portion of the governor drive shaft. Use a soft- bristled

(1) Reassemble and install the engine

brush, if necessary, to remove the grease.

overspeed governor and related parts as shown 'in

(4) Inspect the engine overspeed governor

figure 3-6.

for cracks, loose or damaged terminals, and damaged

(2) Reconnect the electrical leads to the

coupling at the end of the shaft. Rotate the shaft to

terminals at the top of the overspeed governor.

check for rough, catching, or binding operation.

(3) Reconnect the tachometer drive and

Replace a damaged overspeed governor.

tachometer shaft to the governor arm, and lubricate the

(5) Inspect the governor drive shaft for

tachometer drive and overspeed governor (TM 5-4320-

cracks, damaged teeth, distortion and other damage;

258-12).

replace a damaged drive shaft.

(4) Check and, if necessary, adjust the

(6) Inspect all other parts for cracks,

engine overspeed governor (subparagraph a above).

SECTION II. REPAIR OF COOLING SYSTEM COMPONENTS

3-6.

Description of Cooling System

a. Liquid coolant is pumped around the

cylinder walls and valve guides in the cylinder block and

around the tops of the cylinders in the cylinder head to

remove the heat of combustion from the engine. This is

necessary to prevent the excessive heat from damaging

the engine.

b. As the hot coolant is pumped from the

engine, it enters the radiator consisting of tubes and fins

which dissipate the heat to the atmosphere. The fluid

passes into the top of the radiator and out through the

bottom. The cooling fan maintains a blast of air through

the radiator to help dissipate the heat.

c. The coolant from the radiator enters the

water pump which is V-belt driven by the engine to

circulate the coolant through the block and cylinder head

to complete the cycle. The centrifugal water pump is

mounted on the cylinder block.

Oil pressure safety switch

d. The engine is protected from overheating

Coolant temperature safety switch

by coolant temperature safety switch (2, fig. 3-7)

Temperature switch adjusting screw

mounted on the control panel. This switch closes a set

Oil pressure switch adjusting screw

of contacts to stop the engine by grounding the magneto

Oil safety switch pushbutton

primary before engine coolant tem- perature reaches the

point that engine damage can occur. The switch trip

Figure 3-7. Coolant temperature and oil pressure safety

point is adjustable.

switches.

3-10