Here are the most likely culprits and how to check them:
* Radiator itself: A cracked radiator is a common cause. Carefully inspect the entire radiator, looking for cracks, especially at the seams and lower corners. A pressure test at an auto parts store is the best way to definitively rule this out.
* Radiator hoses: Check both the upper and lower radiator hoses for cracks, bulges, or leaks at the clamps. Squeeze the hoses gently; if they're brittle or feel spongy, they need replacing.
* Water pump: The water pump is located on the engine block and circulates coolant. Leaks often manifest as a slow drip or weep from the weep hole (a small hole near the pump shaft). Look for signs of corrosion or wetness around the pump. A visual inspection isn't always conclusive; listening for unusual noises from the pump while the engine is running might reveal a failing bearing.
* Engine block: A crack in the engine block is a serious problem. This is less likely if the leak is localized near the radiator, but if you see antifreeze further down the engine bay it could be a source. Look for wetness or staining on the engine block, especially around the cylinder head and thermostat housing.
* Thermostat housing: This is located on the engine block where the upper radiator hose connects. Check for cracks or leaks around the housing and the gasket.
* Heater core hoses: These run inside the car. While less likely to be directly visible under the radiator, a leak in the heater core hoses can sometimes lead to antifreeze appearing under the car after dripping down from the engine compartment and may show up as a puddle closer to the cabin.
Troubleshooting Steps:
1. Clean the area: Thoroughly clean the area around the radiator and engine with a degreaser to remove dirt and grime, making it easier to spot any leaks. Let it dry completely.
2. Run the engine: Let the engine run for a while (with the hood up, but be cautious of moving parts) and watch carefully for where the antifreeze is leaking from. Have a helper monitor the coolant level in the overflow tank.
3. Pressure test the cooling system: This is the most definitive way to pinpoint a leak. Most auto parts stores offer this service. They'll pressurize the system and look for pressure drops indicating a leak.
4. Dye test (optional): You can add a coolant dye to your system; if there’s a leak, the dye will highlight it under a UV light.
5. Inspect the lower radiator hose: This is very close to the driver's side and often a point for leaks. A small crack or pinhole leak might be easy to miss.
If you can't locate the leak after these steps, it's best to take your Grand Prix to a qualified mechanic for diagnosis and repair. A persistent antifreeze leak can cause serious engine damage.
