* Radiator cap: This is the most common culprit. A faulty radiator cap can fail to maintain proper pressure in the cooling system, leading to leaks around the cap itself or even causing the pressure to force coolant out of a weakened radiator seam. This is often seen as a slow leak, especially when the engine is hot.
* Radiator itself: Cracks or corrosion in the radiator's top tank are possible, though less likely than a bad cap. This would likely be a more substantial leak than a cap problem.
* Upper radiator hose connection: The hose clamp connecting the upper radiator hose to the radiator might be loose or failing, allowing coolant to seep out. This would be visible near the connection point.
* Pressure relief valve (in the radiator cap): While part of the cap, this is worth mentioning separately. If it's malfunctioning, it might be releasing coolant prematurely.
* Less likely, but possible: A very small crack or pinhole leak in the radiator's top tank could be difficult to pinpoint visually but would manifest as a slow leak.
How to troubleshoot:
1. Check the radiator cap: Carefully inspect the cap for damage or corrosion. You can even try replacing it with a new one—it's a relatively inexpensive part.
2. Look closely at the radiator top tank: Examine the tank for any cracks, pinholes, or corrosion, especially around the seam where it meets the radiator core.
3. Inspect the upper radiator hose and clamp: Ensure the clamp is tight and the hose isn't damaged or deteriorated.
4. Pressure test: A radiator pressure test performed by a mechanic is the most definitive way to pinpoint the source of a leak. This involves pressurizing the cooling system to check for leaks under pressure.
It's crucial to address a coolant leak promptly to prevent overheating and potential engine damage. If you're not comfortable performing these checks yourself, take your Grand Prix to a mechanic for diagnosis and repair.
