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Home >> Pontiac >> 2004 >> Aztek Base, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 155 (Engine Cooling System) >> Diagnostic Information and Procedures >> Engine Overheating

Engine Overheating

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
Engine Overheating

Step Action Values Yes No
1 Inspect for a loss of system pressure and/or coolant.
Is there a loss of system pressure and/or coolant?
- Go to Step 2  Go to Step 3 
2 Inspect and repair any faulty hose connections or radiator cap. Fill the system to the proper level, then retest.
Does the engine still overheat beyond the specified value?
125°C (257°F) Go to Step 3  System OK
3 Inspect the coolant concentration for low temperature protection below the specified value.
Is the proper low temperature protection present?
-37°C (-34°F) Go to Step 5  Go to Step 4 
4 Replace the coolant. Refer to Draining and Filling Cooling System (LL8)  or Draining and Filling Cooling System (LM4)  .
Does the engine still overheat?
- Go to Step 5  System OK
5 Inspect the drive belt for excessive wear or low tension.
Is the drive belt worn or is the tension too low?
- Go to Step 6  Go to Step 7 
6 Replace the drive belt. Refer to Drive Belt Replacement in Engine Mechanical - 4.2L.
Does the engine still overheat?
- Go to Step 7  System OK
7 Inspect the radiator fins for obstruction.
Are the radiator fins obstructed?
- Go to Step 8  Go to Step 9 
8 Inspect and clean the radiator. Refer to Radiator Cleaning  .
Does the engine still overheat?
- Go to Step 9  System OK
9 Inspect the water pump for physical damage.
Is the water pump damaged or inoperative?
- Go to Step 10  Go to Step 11 
10 Replace the water pump. Refer to Water Pump Replacement (LL8)  or Water Pump Replacement (LM4)  .
Does the engine still overheat?
- Go to Step 11  System OK
11 Inspect the cooling system passages for obstruction.
Is the cooling system passage blocked?
- Go to Step 12  Go to Step 13 
12 Inspect and flush the system. Refer to Flushing  .
Does the engine still overheat?
- Go to Step 13  System OK
13 Inspect the electro-viscous fan.
Is the electro-viscous fan inoperative?
- Go to Step 14  Go to Step 15 
14 Replace the electro-viscous fan.
Does the engine still overheat?
- Go to Step 15  System OK
15 Inspect for a stuck thermostat. Refer to Thermostat Diagnosis  .
Is the thermostat stuck in the closed position?
- Go to Step 16  Go to Step 17 
16 Replace the thermostat. Refer to Thermostat Replacement (4.2L Engine)  or Thermostat Replacement (5.3L Engine)  .
Does the engine still overheat?
- Go to Step 17  System OK
17 The following factors may cause the engine to overheat:
  • A heavy vehicle payload
  • The A/C system
  • Excess engine oil
  • Restricted air flow through the radiator
  • Extreme air temperature

Correct or repair as necessary.
Does the engine still overheat?
- - System OK