Exhaust fumes coming through vents when heater is turned on

[rollcode3]

Hopefully someone here has an idea about this problem. You guys were able to walk me through a timing belt change in Jan. 06, and I'm hoping your vast knowledge will be able to give me some ideas where to start. My wife has a 2000 Mystique, with the 2.0 L, and it has 96,000 miles on it. When she turns the heater on, there is a light smell of exhaust fumes coming through the vents. I originally told her that maybe it was the exhaust fumes from other cars around her, but I noticed it tonight myself while driving the car, and there were no other cars around. Is it possible for exhaust to get into the cooling/heating system, and if so, where do I start looking?

Any ideas or suggestions would be greatly appreciated.

Thanks

 

[andreslobo]

Look for exhaust leaks in the engine compartment

Look for exhaust leaks in the engine compartment

I'd start looking for an exhaust leak forward of the firewall. Start with a cold engine and listen for noises as the engine warms up. If you hear noises like clicking it MIGHT be simply a bad gasket. If no noises, on a cold day look for vapor coming out of a leak. Plenty of places for it to leak starting at the head to exhaust manifold gasket, then the exhaust manifold to catalytic converter gasket, then the converter to flex pipe (look at flex pipe very carefully), then the flex pipe to exhaust pipe and so on to the back of the car.

If you live in the rust belt, then you might simply have a rusted out exhaust system.

 

[UmmScott]

Another idea

Another idea

Check ur EGR system. Check that pipe comin from the cat to the egr valve, if its leaking u will hear a hissing noise and the pipe will be very hot.

I'd also check the gasket where the egr mounts to the intake manifold.

Its suspicious to me because if the egr system is leaking, the fumes could easily be sucked into the right vent.

Then again, any leak in front of the firewall has the potential to be drawn into the HVAC system when its on...