Section XlI. COOLING SYSTEM

Section

XlI.

COOLING

SYSTEM

b. Cleaning and Inspection.

4-30.

General

( 1 ) Clean thermostat housing seat and gask

The diesel engine is cooled by circulating the engine

surface.

coolant through the radiator, transmission heat

(2) Inspect the thermostat for an accumulation

exchanger, cylinder block, and cylinder head.

o f rust and corrosion.

C o o l a n t is drawn from the bottom of the radiator

c. Testing. Check

operation

thermostat.

by the water pump and circulated through the heat

thermostat

remains

closed overheating of the

e x c h a n g e r , engine block, and cylinder head. During

If thermostat remains open

engine will result.

warm-up

period,

when

coolant

temperture

engine may not reach normal operating tem-

below normal, the coolant is restricted at the

incomplete fuel com-

resulting

perature,

t h e r m o s t a t . A bypass tube connected between the

b u s t i o n and carbon buildup. To check operation of

t h e r m o s t a t housing and the water pump provides

thermostat, suspend it and a thermometer in a

circulation within the engine. As the coolant

c o n t a i n e r of water. Do not let the thermometer or

temperature rises above 160 to 170F., the

t h e r m o s t a t touch the bottom or sides of container.

thermostat valve opens, restricting the bypass

H e a t the water, agitate to maintain an even tem-

system and coolant is circulated through the

perature. As water is heated the thermostat should

r a d i a t o r . This section contains information on the

begin to open at 160 to 170F., and be fully open at

maintenance of the cooling system components

approximately 190F.

which is the responsibility of organizational

d . Installation.

maintenance

personnel.

(1) Affix new gasket to thermostat housing

a n d seat thermostat in housing so that the spring

4-31. Thermostat Housing and Thermostat

( o r bellows) is down or toward the hot water side

a. Removal.

w i t h unit bolted to cylinder head.

(1) Drain the cooling system to below the

(2) Refer to figure 4-14 and install thermostat

t h e r m o s t a t housing by opening the drain valve.

housing and hose.

(2) Refer to figure 4-14 and remove the

thermostat housing and thermostat.

4-18