Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Heater core leak

I have a 1996 Ford Escort LX - 2.9L/ 5spd with over 100M miles. As the cold weather set in I have noticed an engine/exhaust type smell coming from the heater blower when the car is either idling or at a stop light. Once I get moving the smell either goes away or diminishes considerably.

I do not see any coolant leaking inside or out (the coolant reservoir levels have not gone down).

The exhaust system is original to the car and it does not make any excessive noise like a “hole in the exhaust”.

Please advise as to how to check for a heater core leak or exhaust leak?



It doesn’t sound like either. It is more likely that you have a small engine oil leak (probably valve covers), and you smell that when the car is not moving. Open the hood while the engine is still on or has just been switched off, you will get the same smell. The fresh air intake for the heater is at the windshield, behind the hood.

A heater core leak will cause the windshield to fog up instantly when you turn the defroster on…You can hold a rag over the tailpipe and see it the exhaust system will build up pressure against the rag…If not, it’s leaking…