How to Diagnose an Engine Coolant Leak

Coolant is combustible. Check the coolant levels in your vehicle when it is cool. If the engine is hot, it could explode coolant when you open the cap.

Find the reservoir marked coolant under the hood. Look on the side of it for a fill line. It usually says 'cold level' or has a mark where the level must be when the engine has cooled.

Add a little coolant to the fill line, and look for any coolant in the overflow chamber located below the reservoir.

Look back under the hood in a day or two to see if the coolant level has gone down again. If it has a leak is a possible cause.

Keep an eye on your temperature gauge. A car loosing coolant runs hotter than normal. If there is an unusual odor or smoke, that is also an indicator of trouble with the coolant. Get the car to a shop for further inspection.

Note any spills or leaks under the places you park. When you see a puddle of green colored fluid it is typically a leak. Wave your hand six inches from the puddle to smell it. Coolant has a smell that some describe as sulfur or sweet.

Listen for a whistling sound. An engine leaking coolant may make a high pitched boiling sound.