Water leaking under a car
The buyer question: "water leaking under car"
Do not drive if the temperature rises, coolant is low, steam appears, or the leak is heavy. A cooling-system leak can become an overheating event.
What could cause it
More than one problem can cause the same symptom. These are places to inspect, not a diagnosis.
- Normal air-conditioning condensation
- A coolant leak from a hose, radiator, pump, or reservoir
- Windshield-washer fluid or another water-like fluid
- A leak that only looks like water until it is checked
Safe things to check
Keep clear of moving parts, hot components, and traffic. Use the owner's manual for vehicle-specific instructions.
- Place clean cardboard under the parked car and note color, smell, and location
- Check the coolant reservoir only when the engine is fully cool and according to the manual
- Do not open a hot pressurized cooling system
Stop driving if the leak is colored or sweet-smelling, the temperature gauge rises, steam appears, or the coolant level drops. Arrange an inspection instead of topping up and driving on.
What a mechanic may check
A mechanic may identify the fluid, pressure-test the cooling system, inspect hoses, the radiator, pump, thermostat housing, and A/C drains, and look for signs of overheating.
If you are considering this car
Ask the seller to show the car parked overnight and have the leak identified by an independent shop. A clean driveway after the car is moved does not prove there is no leak.
Questions for the seller
- Is the liquid clear and odorless, or does it have color or a sweet or oily smell?
- Does the A/C run when the liquid appears?
- Has the cooling system or any hose, radiator, or water pump been repaired?