TM 5-3895-346-14
COOLING SYSTEM
ENGINE OVERHAUL
Drain Cooling System
Drain the cooling system by opening the cylinder block and radiator (or heat exchanger) draincocks and
removing the cooling system filler cap. Removal of the filler cap permits air to enter the cooling passages and
the coolant to drain completely from the system.
Draincocks are located as indicated in Table 2. Radiators that do not have a draincock are drained through the
oil cooler housing drain.
If freezing weather is anticipated and the engine is not protected by antifreeze, drain the cooling system
completely when the engine is not in use. Leave all of the draincocks open until the cooling system is refilled.
Should any entrapped water in the cylinder block, radiator, or other engine parts freeze, it will expand and may
result in damage to the engine.
TABLE 2
COOLANT DRAIN VALVES
Side of Block
Oil Cooler
Opposite Oil
Engine
or
Cooler or
Coolant Inlet
Coolant Inlet
Side of Block
Bottom of oil
Behind blower
4-53
cooler, cool-
drive or gover-
lant inlet,
nor near rear of
and behind
block
blower drive
or governor
near rear of
block
Flushing
If a coolant filter is used and properly maintained, the cooling system need not be flushed. Otherwise, the
cooling system should be flushed each spring and fall. The flushing operation cleans the system of antifreeze
solution in the spring and removes the summer rust inhibitor in the fall, cleaning the system for the next
solution. The flushing operation should be performed as follows:
1. Drain the previous season's solution from the engine.
2. Refill with soft, clean water.
CAUTION
If the engine is hot, fill slowly to
prevent rapid cooling and distortion of
the engine castings.
3. Start the engine and operate it for 15 minutes to thoroughly circulate the water.
4. Drain the unit completely.
5. Refill with the solution required for the coming season.
Cooling System Cleaners
If the engine overheats, and the fan belt tension and water level have been found to be satisfactory, clean and
flush the entire cooling system. Remove scale formation by using a reputable and safe descaling solvent.
Immediately after using the descaling solvent, neutralize the system with the neutralizer. It is important that the
directions printed on the container of the descaler be thoroughly read and followed.
After the solvent and neutralizer have been used, completely drain the engine and radiator and reverse-flush
before filling the system.
Reverse-Flushing
After the engine and radiator have been thoroughly cleaned, they should be reverse-flushed. The water pump
should be removed and the radiator and engine reverse-flushed separately to prevent dirt and scale deposits
clogging the radiator tubes or being forced through
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