Water Pump and Thermostat

(2) Install hoses (4 and 10) on radiator and engine

g. Corrosion Inhibitor. Use a corrosion inhibitor

and secure with clamps (3 and 4). Tighten clamps

compound (FSN 6850-281-1989) in coolant system

securely.

using water only. Do not use corrosion inhibitor and

(3) Refer to paragraph 3-54 and connect trans-

antifreeze solution in the cooling system. Add eight

mission cooler lines to radiator.

ounces of corrosion inhibitor compound to ten quarts

(4) Refer to figure 3-21 and install radiator grille.

of water.

(5) Close drain valve (12) on radiator and drain

3-38. Water Pump and Thermostat

valve on engine inlet elbow.

a. Removal. Refer to figure 3-23 and remove the

(6) Fill radiator and cooling system (d below ).

thermostat and water pump as follows:

d. Draining and Filling Cooling System.

(1) Drain coolant system (para 3-37) to bring

(1) To drain cooling system, remove radiator cap

coolant level below thermostat housing (1).

(1, fig. 3-22) and open drain valve (12) and drain

(2) Remove two screws (23) and lock washers (24)

valve on engine inlet elbow.

securing housing to water pump. Remove housing

(2) If cooling system is not to be refilled, attach a

and gasket (25).

notice to steering wheel to warn other personnel that

(3) Remove thermostat (2) from top of water

radiator has been drained.

(3) After draining and before refilling, flush

pump.

(4) Refer to paragraph 3-39 and remove the fan

radiator (e below) if radiator requires cleaning.

(19) and fan belt (18).

(4) Use soft water only in the cooling system,

(5) Disconnect bypass tube (6) and remove elbow

except in emergency conditions. Add anti-freeze or

(5) from water pump assembly (3).

corrosion inhibitor to water as applicable.

(5) With drain cocks closed, fill cooling system

(6) Remove screw (17) and lock washer (16) and

remove adjusting strap (15) from water pump.

through filler cap opening until coolant level reaches

(7) Remove two screws (14) and lock washers (13)

filler neck. Start engine and allow to idle until ther-

and remove water pump assembly (3) and gasket (4)

mostat opens and allows coolant circulation.

from engine.

(6) Add coolant to bring to proper level.

b. Testing Thermostat. Fill a container with suffi-

e. Cleaning and Flushing.

(1) Use a good grade of commercial flushing

cient water to cover thermostat. Suspend thermostat

in water.

compound. Follow directions provided with com-

(1) Suspend a reliable thermometer in water.

pound.

Keep thermometer bulb off bottom of container.

(2) Check radiator for leaks after slushing and

(2) Heat water and stir water to assure even

cleaning.

(3) To pressure flush radiator to clean obstructed

heating.

(3) When water reaches a temperature between

radiator tubes, disconnect upper and lower hoses (b

above).

160 F and 165 F, thermostat should start to open.

(4) Connect a pressure water hose to the lower

Thermostat should be completely open at 185 F to

190 F.

radiator connection, using a suitable adapter.

(4) Lift thermostat from container. Thermostat

(5) Plug the upper hose connection on the radia-

should close with a pronounced action after being ex-

tor. Remove the radiator cap.

posed to surrounding air.

Caution: Do not use more than six pounds of

(5) Discard a thermostat that does not pass the

pressure in flushing the radiator. Excess pressure

above test.

may rupture tubes in the radiator or oil cooler.

c. Installation. Refer to figure 3-23 and install the

(6) Turn on water and force water upward

through radiator to loosen foreign material from

thermostat and water pump as follows:

tops of tubes. Material will be flushed out of top of

(1) Install water pump assembly (3) and new

radiator with water.

gasket (4) on engine and secure with two screws (14)

and lock washers (13).

(7) Disconnect water hose and connect hoses to

radiator and engine.

(2) Install adjusting strap (15) and secure with

screw (17) and lock washer (16).

(8) Fill radiator and cooling system and check for

leaks.

(3) Refer to paragraph 3-39 and install engine

f. Anti-freeze Protection.

fan (19), fan belt (18), and pulley (22) on engine.

(1) Drain any anti-freeze solution from the cool-

(4) Install elbow (5) in water pump assembly

and connect by-pass tube (6) to elbow.

ing system at the end of each cold season and discard.

(5) Install thermostat (2) in top of water pump (3).

(2) Refer to table 2-1 (para 2-1) for anti-freeze

and amounts required for protection.

(6) Install new gasket (25) and thermostat hous-

3-24