Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSPONTIAC2008GRAND PRIX BASEREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 304 (ENGINE COOLING)DIAGNOSTIC INFORMATION AND PROCEDURESENGINE OVERHEATING
2008 Pontiac Grand Prix Base
Engine Overheating
2008 Pontiac Grand Prix BaseSECTION Engine Overheating
WARNING: This page is about a different car, the 2008 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
| 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 or P0118
. Is the sensor operating properly? |
Go to Step 7 | Go to Step 8 |
| 7 | Inspect for the following:
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 |
|
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. 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 Engine Coolant 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 (Electric) . Is the repair complete? |
System OK | - |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.