Section X. MAINTENANCE OF COOLING SYSTEM

TM 5-4320-234-12

f. If the governor cannot operate the throttle lever

adjusting screw (11) and compensate for speed change

with the speed adjusting screw (10).

on the carburetor through the full operating range, it will

d. When the governor range of action is properly

be necessary to adjust the length of the throttle rod (2)

by loosening the nut (3) and adjusting the position of the

adjusted, allow the engine to run at governed speed, no

ball joint (4).

load, and check for surging. If surging is noted, turn in

g. When the governor adjustment is completed,

the surge adjusting screw (7) just far enough to

eliminate the surging.

tighten the speed adjusting lock screw (9) to lock the

e. The surge adjustment can also be made by

cam in position.

Make sure all locking nuts are

tightened.

using the tachometer. With the engine running at

h. If the governor cannot be adjusted, refer

governed speed, no load, turn in the surge adjusting

screw (7) until the engine speed increases 10 to 20 rpm

problem to direct support maintenance.

and tighten the locking nut. If the carburetor and linkage

are properly adjusted, surge will disappear.

Section X. MAINTENANCE OF COOLING SYSTEM

4-28. Description

radiator clean and free from bugs, dirt, and debris. It is

also necessary to keep the interior of the radiator and

a. The engine cooling system is a conventional

the engine block flushed out to prevent accumulations of

rust and scale which can prevent proper heat transfer.

automotive type in which coolant is circulated through

the cylinder block to remove the combustion heat from

4-29. Cleaning and Flushing the Cooling System

the operating parts of the engine. The water is then

passed through the radiator, which acts as a large heat

a. Clean the exterior of the radiator by flushing a

exchanger to dissipate the heat to the atmosphere. The

stream of water through it in a direction opposite that of

water pump maintains the flow of coolant through the

the cooling fan flow. Since this engine uses a pusher

engine.

type fan, it is necessary to squirt the water from the

b. A thermostat is installed in the engine to prevent

outside of the radiator inward toward the engine. Cover

the engine with a piece of plastic film to prevent

the flow of coolant into the radiator when the engine is

saturating the components before attempting to flush the

cold. Instead, the coolant is bypassed directly to the

exterior of the radiator.

water pump and recirculated into the block without being

cooled in the radiator. In this way, the engine heats

b. Disconnect the hoses connecting the engine and

more rapidly, providing efficient operation more quickly.

radiator. With the radiator cap closed tightly, use a

When the coolant in the cylinder block reaches

flushing gun as shown in figure 4-13 to reverse-flush the

operating temperature, the thermostat opens and the

radiator. Fill the radiator with water, then blow out the

coolant is forced to flow through the radiator.

water with compressed air, applying pressure slowly to

c. To ensure efficient operation of the cooling

prevent radiator damage. Repeat several times until the

expelled flushing stream is clear.

system, it is important to keep the exterior of the

4-26