a. General. Continuous operation of truck at high speeds, or under long hard pulls in lower
gear ratios on steep grades, or in soft terrain, may cause engine to overheat. Avoid the
continuous use of low gear ratios whenever possible. Continuously be alert for overheating. Halt
the equipment for a cooling-off period whenever necessary, if the tactical situation permits.
b. Cooling System. Scale and rust in the cooling system form faster during operation in
extremely high temperatures. For this reason, corrosion inhibitor compound should always be
added to the cooling liquid. Avoid the use of water that contains alkali, which causes scale and
rust. Fill the radiator with rain water whenever possible. Refer to TB 750-651 for use of engine
Extreme care must be exercised in removing filler cap when temperature gage reads
(1) Make frequent inspections of cooling system for proper coolant level in the radiator
and proper hose connections. Check tension adjustment on the fan belt, and be sure that the
hose lines are not cracked and/or leaking.
(2) If your truck engine is constantly overheating, inspect the radiator fins (l). Clean out
sand, dust, or insect accumulation with compressed air.
(3) Remove the filler cap (2), open the engine block drain cock (4), and the radiator
drain cock (3), flush the system if necessary, then close the drain cocks(3) and (4). Be sure to
refill the system with proper coolant.
(1) In torrid zones, check level of electrolyte in cells daily. Refill with pure distilled
water. If distilled water is not available, rain or drinking water may be used. Water with a high
mineral content will eventually damage the batteries, and should be avoided.