Coolant leak

Symptoms

• Puddle of colored fluid under the front of the car
• Sweet smell inside or outside the car
• Coolant reservoir level dropping between checks
• Occasional overheating if the leak is significant

Likely causes

• CommonCracked or loose radiator hoseRubber hoses degrade with age and heat cycles, eventually cracking or loosening at the clamps.
• CommonRadiator leakCorrosion or impact damage can create pinholes or cracks in the radiator itself.
• CommonWater pump seal leakThe water pump's shaft seal wears over time and leaks from a small weep hole underneath the pump.
• PossibleBlown or leaking head gasketA more serious leak that can also cause white exhaust smoke or oil contamination.
• PossibleCracked coolant reservoirThe plastic overflow tank can crack from age or heat and leak, usually only when the system is pressurized.

What to do

1. Place cardboard under the car to catch drips and help pinpoint the leak's location front-to-back and side-to-side.
2. Check the coolant color and confirm it's not transmission fluid (reddish, oilier) or engine oil (dark, thick).
3. With the engine cool, visually inspect hoses, the radiator, and the area under the water pump for wetness or crusty residue.
4. Check the coolant reservoir level and top off temporarily with the correct coolant type if low.
5. Avoid driving long distances if the level keeps dropping quickly, since running low risks overheating.
6. Have a mechanic pressure-test the cooling system to find leaks that aren't obvious when the system isn't under pressure.
7. Get the specific hose, gasket, or component repaired rather than just topping off coolant repeatedly.

Tools and parts

• Cardboard or leak mat
• Flashlight
• Gloves

When to call a pro

See a mechanic to pressure-test and pinpoint the leak if it's not obvious, especially if coolant keeps disappearing without a visible puddle.

Safety