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Home >> Pontiac >> 2002 >> Aztek AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 620 (Engine Cooling System) >> Diagnostic Information and Procedures >> Engine Overheating

Engine Overheating

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 Chevrolet Tahoe, 2002 Chevrolet Suburban, and 2002 Chevrolet Avalanche. 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: ECT SENSOR CIRCUIT -- LOW VOLTAGE (4.8L, 5.3L, & 6.0L ENGINE) , DTC P0118: ECT SENSOR CIRCUIT -- HIGH VOLTAGE (4.8L, 5.3L, & 6.0L ENGINE) , or to DTC P0117: ECT SENSOR CIRCUIT -- LOW VOLTAGE (8.1L ENGINE) , DTC P0118: ECT SENSOR CIRCUIT -- HIGH VOLTAGE (8.1L ENGINE) .
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 3 
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 (4.8L, 5.3L, and 6.0L Engines)  or Water Pump Replacement (8.1L Engine) .
  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 (4.8L, 5.3L, and 6.0L Engines) .
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 -