1996 Ford Mustang Burnt nasty smell when I turn the heater

JDORMAY

MEMBER
1996 FORD MUSTANG
V8
2WD
MANUAL
160,000 MILES

How can I find out what is causing a smell when my heater is on? Not a gas smell, and I don't know what coolant smells like, and it's not sulfurous. First time I smelled it I thought it was tires or brakes because the odor reminded me of burnt rubber. But then I had just started the car, and turned on the defroster with high fan, and the odor really showed up. No smell if I turn the heat off, no smell using A/C. No wet spots under the dash, no visible sign of dripping liquids under the car. Oil pressure is fine, temperature is normal, coolant level is full. Only recent repair was 6 months ago when Ford dealer replaced the intake manifold, and there was no odor until now. I've talked to 2 different mechanics, one says it might be a leak, another said maybe the head gasket (which I doubt because the performance is still great and there is no visible residue around it.) Brakes were checked and are fine. Just a nasty smell when the heat is on.

1 Reply

KHLOW2008

MECHANIC
41,814 POSTS

Hi jdormay,

Thank you for the donation.

Coolant smells sweet when heated up and the smell that you described do not fit.

With no overheating or coolant losses, that would rule out a possible leak or bad head gasket.

It is possible some foreign materials had gotten to the heater core and when it is turned on, the heat fomr the heater is causing the smell.

If you use any from of air freshener in the vehicle, some can cause a bad smell when the air freshener sticks to the heater core and over time it would turn into a foul smell.

If air freshener or any other form of external causes, the smell would normally be intense at initial turning on of the heater and goes away after a short period. It would recurr again the next time the heater is turned ON.

You would need to remove the heater core to check and clean to resolve the problem.