TM 5-2420-230-24-2
B3.9 and B5.9 Series Engines
Cooling System - Air or Combustion Gas Test (008-019)
Section 8 - Cooling System - Group 08
Page 8-21
If no air is found in the cooling system, do the following:
Remove the test equipment.
Check the coolant level, and fill if necessary.
Install the radiator pressure cap.
Operate the engine until it reaches a temperature of
80C [176F], and check for coolant leaks.
Combustion Gas Leak
Fan, Shutter, or Heater Air Control Valve
CAUTION
The engine can overheat with the fan control or the
shutter air control valve disconnected. Monitor the en-
gine coolant temperature while performing this test.
The coolant temperature must not exceed 100C
[212F].
Repeat the test for air in the cooling system as previously
described in Procedure 008-019. If no air is found in the
cooling system with the air control valve(s) isolated, install
a new control valve.
NOTE: Start the engine, and run for 5 minutes before
testing for air in the coolant. This will allow any trapped air
to purge from the system.
Air Compressor
CAUTION
The air compressor discharge line must be discon-
nected at the compressor to allow the compressor to
discharge air to the atmosphere to prevent the com-
pressor from overheating during this next test. Do not
run the engine over 5 minutes with components iso-
lated from the cooling system. Component damage can
occur.
L-1077
