TM 5-3895-383-24
20.
Operation at high altitude:
The cooling capacity of the cooling system goes
down as the engine is operated at higher altitudes.
A system, under pressure, large enough to keep
the coolant from boiling must be used.
21.
Engine used in a lug condition:
"Lugging" can occur when there is too much load
applied to the engine or the engine is run at a lower
rpm. This low rpm causes a reduction in air flow
through the radiator, and a reduction in the flow of
coolant through the system. This combination of
less air and less coolant flow during high input of
fuel will cause above normal heating.
22.
Fuel setting:
A high fuel setting causes a high heat rejection. If
the engine cooling system is designed for a
particular heat rejection and it is changed the
cooling system is no longer capable of cooling the
engine.
23.
Fuel injection timing:
Check and make necessary adjustments as per
Testing and Adjusting Section of the Service
Manual.
Problem 27: Below Normal Coolant Temperature
Probable Cause(s):
Long Idle Periods
Very Light Loads
Water Temperature Regulator
Air Vent Valve
Fan Clutch Engaged
1.
Long idle periods:
When the engine is running with no load, only a
small quantity of fuel is burnt and engine heat is
removed too fast.
2.
Very light load:
Very light loads can cause below normal heating
because of the low heat input of the engine. A
slight restriction of air flow through the radiator will
help to correct this problem.
3.
Water temperature regulator:
A water temperature regulator that is "stuck" open
(will not move to the closed position) will cause
below normal heating. A regulator that is stuck
between the open and closed positions, or a vent
valve that is stuck open, can cause below normal
coolant temperatures when the engine has a light
load.
4.
Air vent valve:
An air vent valve located in the water temperature
regulator that is stuck open, can cause below
normal coolant temperatures when the engine has
a light load.
5.
Fan clutch engaged:
Electric fan clutch engaged. Check temperature
sensor.
Problem 28: Exhaust Temperature Is Too High
Probable Cause(s):
Air Inlet System Has A Leak
Exhaust System Has A Leak
Air Inlet Or Exhaust System Has A Restriction
Incorrect Fuel Injection Timing Dimension
Fuel Setting Too High
Engine Operated In A Lug Condition
1.
Air inlet system has a leak:
Check pressure in the air inlet manifold. Look for
restriction at the air cleaner. Correct any leaks.
2.
Exhaust system has a leak:
Find cause of exhaust leak. Make repairs as
necessary.
3.
Air inlet or exhaust system has a restriction:
Remove restriction.
4.
Incorrect fuel injection timing dimension:
Check and make necessary adjustments as per
Testing and Adjusting Section of the Service
Manual.
5.
Fuel setting too high:
Check and make necessary adjustments as per
Testing and Adjusting Section of the Service
Manual. See Fuel Setting And Related Information
Fiche for the correct fuel setting.
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