* Leaking heater core: This is the most common cause. The heater core is a small radiator located inside the car's dashboard that warms the air for the cabin. A leak allows coolant to drip into the air handler, and then the smell is distributed through the vents. This is a significant repair as it often requires dashboard disassembly.
* Leaking water pump: While less likely to directly smell in the cabin, a significant leak from the water pump could eventually lead to coolant entering the cabin if it mixes with the air handler's drainage system.
* Cracked engine block or head gasket: These are more serious issues. A crack or blown head gasket allows coolant to mix with engine oil or enter the combustion chamber. While you might not directly smell it in the vents at first, the pressure buildup could force coolant into areas that eventually lead to its entry into the air handler. This would often be accompanied by other symptoms like overheating, white exhaust smoke, or milky oil.
What to do:
1. Check the coolant level: Open the hood and locate the coolant reservoir. Is the level low? If so, this supports the leak theory. Check for any visible leaks around the engine and radiator.
2. Inspect the floor mats: Look for any signs of dampness or puddles under the passenger side carpet (most likely location for a heater core leak).
3. Don't drive the car extensively: Continuing to drive with a coolant leak can lead to overheating and potentially serious engine damage.
4. Get it checked by a mechanic: Diagnosing and repairing a coolant leak, especially a heater core leak, requires professional expertise. A mechanic can pinpoint the source of the leak and recommend the appropriate repair. Ignoring the problem will only worsen it and lead to greater expense later.
The smell is a serious warning sign; don't delay getting it checked.
