Figure 2-25. Heat cracking damage to cylinder block resulting from slush ice freezeup in radiator.

prescribed requirements.

c. Antifreeze Protection

(1) When cooling system protection is required for

temperatures no lower than -55F prepare a solution in

accordance with Instructions in the furnished guide (Table

2-2).

Table 2-2. Table of Antifreeze Protections

Pints of Antifreeze Compound

Protection To

Required to Make One Gallon

of Antifreeze Solution

+ 10 F

0 F

2-3/4

-10 F

3-1/4

-20 F

3-1/2

-30 F

Figure 2-25. Heat cracking damage to cylinder block

-40 F

4-1/2

resulting from slush ice freezeup in radiator.

-50 F

4-1/2

-60 F

b. Antifreeze, Another liquid must be added to the

water in order to prevent it from freezing.

Water

(2) In areas where the lowest temperature

containing antifreeze will not cause freeze-cracking

encountered is below -55F, use arctic-type antifreeze,

damage from expansion and will continue to circulate

freely in the cooling system at very low temperatures if the

MIL-A-11755.

proper amount of antifreeze has been added. Methanol,

ethanol, and ethylene glycol are the types of antifreeze

CAUTION

commonly used in civilian vehicles. However, antifreeze

Do not dilute arctic-type antifreeze with water or

compound (ethylene glycol type) is the only type of

inhibitor. It is ready for use as issued.

antifreeze material authorized for use in water-cooled

military engines.

d. Antifreeze Installation Servicing the engine

(1) Antifreeze inhibited solution, FSN 6850-181-

cooling system for operation at anticipated temperatures

7929, may be retained in engine cooling systems for a

below +32F is performed as follows:

two-year period from fill date.

(1) Completely drain coolant from system with

(2) Arctic-Type antifreeze, 6850-174-1806, will be

engine ,warmed up above specified thermostat-opening

replaced on an annual basis, preferably at the beginning of

temperature.

the cold weather season.

(2) Fill system with water, run engine at fast idling

(3) In climates where temperature does not fall

speed until thermostat full open temperature is reached,

below +32F and where maximum engine cooling is

and drain water.

required, the use of water with dissolved inhibitor, FSN

(3) Perform preventive cleaning of system if coolant

6850-753-4967, is authorized. Antifreeze protection during

is rusty or otherwise contaminated, or radiator is rusty or

a seasonal period when temperature is expected to fall

greasy inside (para 2-21).

below +32F is required. This protection consists of :

(4) Determine required amount of antifreeze

(a) One ounce corrosion Inhibitor for every two

compound from protection guide (Table 2-2).

quarts water used in preparing the solution.

(5) Fill system about one-third full of water, add

(b) Use of arctic-type antifreeze in areas where he

required amount of antifreeze, and finish filling with water,

lowest temperature encountered is below -55F.

but leave room for expansion.

(6) Run engine at fast idling speed with radiator

covered until thermostat full open temperature is reached

NOTE

to release any trapped air and thoroughly mix solution (fig

In an emergency, where antifreeze solution or

2-26).

inhibited water is not available, the use of water

(7) Tighten hose clamps and inspect for leakage.

without inhibitor Is authorized on a temporary

basis, with the circumstance noted on DA Form

91OR-14 At the earliest opportunity, necessary

action will be taken to restore coolant to the

2-23