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Home >> Hummer >> 2003 >> H2 >> Repair and Diagnosis >> External Pages >> Different car >> Section 603 (Engine Cooling System) >> Diagnostic Information and Procedures >> Engine Overheating

Engine Overheating

WARNING: This page is about a different car, the 2004 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
Engine Overheating

Step Action Yes No
1 Inspect for a missing or damaged radiator side or upper baffle and/or radiator air deflector.
Is the baffle and/or deflector missing or damaged?
Go to Step 8  Go to Step 2 
2 Inspect for a loss of coolant.
Is there a loss of coolant?
Go to Step 3  Go to Step 4 
3 Fill the system to the specified level.
Does the engine overheat?
Go to Step 4  System OK
4 Inspect for low temperature protection.
Is the coolant to the correct concentration?
Go to Step 5  Go to Step 8 
5 Inspect for a loss of cooling system pressure.
Is there a loss of system pressure?
Go to Step 8  Go to Step 6 
6 Inspect for a faulty engine coolant temperature (ECT) sensor. Refer to DTC P0117 and DTC P0118 in Engine Controls - 4.8L, 5.3L, and 6.0L.
Is the sensor operating properly?
Go to Step 7  Go to Step 8 
7 Inspect for the following:
  • Damaged coolant surge tank
  • Leaking hose
  • Bad/Incorrect surge tank or radiator cap

Were any of the above found?
Go to Step 8  Go to Step 10 
8 Repair or install new parts as necessary, then retest.
Does the engine overheat?
Go to Step 9  System OK
9 Inspect for incorrect drive belt tension.
Is the belt tension correct?
Go to Step 10  Go to Step 8 
10
  1. Remove the water pump. Refer to Water Pump Replacement .
  2. Inspect for a damaged water pump shaft/hub.
Is the water pump driveshaft damaged or is the seal leaking?
Go to Step 8  Go to Step 11 
11 Inspect for obstructed radiator air flow or bent radiator fins.
Is the radiator air flow obstructed?
Go to Step 8  Go to Step 12 
12 Inspect for blocked cooling system passages.
Are the cooling system passages blocked?
Go to Step 8  Go to Step 13 
13 Inspect for inoperative fan clutch. Refer to Fan Clutch Diagnosis .
Is the fan clutch operating correctly?
Go to Step 14  Go to Step 8 
14 Inspect the thermostat. Refer to Thermostat Diagnosis .
Is the thermostat stuck in the closed position?
Go to Step 15  Go to Step 16 
15 Replace the thermostat. Refer to Thermostat Housing Replacement .
Does the engine overheat?
Go to Step 16  System OK
16 Inspect the radiator cooling capacity.
Is the proper sized radiator being used on the vehicle?
Go to Step 3  Go to Step 17 
17 Consult the current parts catalog and replace the radiator. Refer to Radiator Replacement .
Is the repair complete?
System OK -