TM 5-3805-291-23-1
COOLING SYSTEM TESTS, INSPECTIONS, AND ADJUSTMENTS - CONTINUED
0012 00
COOLING SYSTEM TEST - CONTINUED
Cooling System Check (Overheating) - Continued
4.
Check for hydraulic driven fan that is not turning at the correct speed can cause improper air speed across the radiator
core. Refer to Hydraulic Fan Speed Test and Adjustment (WP 0015 00). The lack of proper air flow across the radiator
core can cause the coolant not to cool to the proper temperature differential.
5.
Check the water temperature gage. A water temperature gage which does not work correctly, will not show the correct
temperature. Refer to Cooling System Inspection in this work package. Connect MSD (WP 0005 00) and compare cool-
ant temperature displayed in ET to temperature to actual coolant temperature. Use a thermometer to record temperature
of coolant.
6.
Check the radiator.
a.
Check the radiator for a restriction to coolant flow. Check the radiator for debris, dirt, or deposits on the inside of
the radiator core. Debris, dirt, or deposits will restrict the flow of coolant through the radiator (WP 0191 00).
b.
Check for debris or damage between the fins of the radiator core. Debris between the fins of the radiator core
restricts air flow through the radiator core. Refer to Cooling System Inspection in this work package.
7.
Check the filler cap. A pressure drop in the radiator can cause the boiling point to be lower. This can cause the cooling
system to boil. Refer to Cooling System Test in this work package.
8.
Check the fan and/or the fan shroud. The fan shroud must be positioned correctly. Ensure that the position of the fan
shroud is correct (WP 0192 00).
9.
Check the cooling system hoses and clamps (WP 0043 00). Damaged hoses with leaks can normally be seen. Hoses that
have no visual leaks can soften during operation. The soft areas of the hose can become kinked or crushed during opera-
tion. These areas of the hose can cause a restriction in the coolant flow. Hoses become soft and/or get cracks after a
period of time. The inside of a hose can deteriorate and the loose particles of the hose can cause a restriction of the cool-
ant flow.
10.
Check for restriction in the air inlet system. A restriction of the air that is coming into the engine can cause high cylinder
temperatures. High cylinder temperatures cause higher than normal temperatures in the cooling system. Refer to Air
Inlet and Exhaust System Inspection (WP 0011 00).
a.
If the measured restriction is higher than the maximum permissible restriction, remove the foreign material from
the engine air cleaner element or install a new engine air cleaner element (TM 5-3805-291-10).
b.
Check for a restriction in the air inlet system again.
c.
If the measured restriction is still higher than the maximum permissible restriction, check the air inlet piping for a
restriction (WP 0034 00).
11.
Check for restriction in the exhaust system. A restriction of the air that is coming out of the engine can cause higher cyl-
inder temperatures. Refer to Air Inlet and Exhaust System Inspection (WP 0011 00).
a.
Make a visual inspection of the exhaust system. Check for damage to exhaust piping or for a damaged muffler.
b.
If the measured restriction is higher than the maximum permissible restriction, there is a restriction in the exhaust
system. Repair the exhaust system, as required (WP 0040 00).
12.
Check the shunt line, if the shunt system is used. The shunt line must be submerged in the expansion tank. A restriction
of the shunt line from the radiator top tank to the engine water pump inlet will cause a reduction in water pump effi-
ciency. A reduction in water pump efficiency will result in low coolant flow and overheating (WP 0042 00).
13.
Check the thermostat. A water thermostat that does not open or a thermostat that only opens part of the way can cause
overheating. Replace thermostat if necessary (WP 0044 00).
14.
Check the water pump. A water pump with a damaged impeller does not pump enough coolant for correct engine cool-
ing. Remove the water pump and check for damage to the impeller (WP 0045 00).
0012 00-5
