COOLING SYSTEM TESTS, INSPECTIONS, AND ADJUSTMENTS - CONTINUED
COOLING SYSTEM TEST - CONTINUED
Cooling System Check (Overheating) - Continued
Check the air flow through the engine compartment. The air flow through the radiator comes out of the engine compart-
ment. Ensure that the filters, AC, and similar items are not installed in a way that prevents the free flow of air through
the engine compartment.
Consider high outside temperatures. When outside temperatures are too high for the rating of the cooling system, there
is not enough of a temperature difference between the outside air and coolant temperatures.
Consider high altitude operation. The cooling capacity of the cooling system goes down as the engine is operated at the
higher altitudes. A pressurized cooling system that is large enough to keep the coolant from boiling must be used.
The engine may be running in the lug condition. When the load that is applied to the engine is too large, the engine will
run in the lug condition. When the engine is running in the lug condition, engine rpm does not increase with an increase
of fuel. This lower engine rpm causes a reduction in air flow through the radiator. This lower engine rpm also causes a
reduction in coolant flow through the system. This combination of less air and less coolant flow during high input of
fuel will cause above normal heating.
Testing Radiator and Cooling System for Leaks
When engine has cooled, loosen filler cap to release any remaining pressure from cooling system. Remove filler cap
Check coolant level in cooling system (TM 5-3805-291-10).
Pressurize cooling system with cooling system pressure tester to 3 psi (20 kPa) over operating pressure of filler cap.
N OT E
If no leakage is observed or ifcooling system pressure tester remains constant for five minutes,
cooling system does not leak.
Internal leakage of cooling systemexists if reading on cooling system pressure tester goes down
and no outside leakage is observed.
Check outside of radiator for leakage. Replace radiator if necessary (WP 0191 00).
Check all connections and hoses of cooling system for leaks. Make repairs, as required.
If pressure reading decreases within a five minute period and no visible signs of external leakage exist, there is an inter-
nal leak. Inspect and/or replace engine oil cooler (WP 0027 00), transmission oil cooler (WP 0205 00), cylinder head
gasket, cylinder head (WP 0172 00), or engine (WP 0171 00) as necessary. Coolant in transmission oil indicates an
internal leak in transmission oil cooler. Coolant in engine oil indicates an internal leak in engine oil cooler, cylinder head
gasket, cylinder head, or cylinder block.
Close hood (TM 5-3805-291-10).
END OF WORK PACKAGE