I have a 1998 Accord and just had the flex pipe replaced. Before replacing, when the heater fan was on, it seemed to draw exhaust fumes into the car. After replacing the flex pipe which had a hole, the problem is still there. It is quite a severe smell of exhaust to the point where I cannot have the heater fan on while the car is at a standstill - while driving there is no problem and if the fan is not on, there is no problem. If the heater is set to the recycle setting, there is no smell even when at a standstill. There is a smell of exhaust when walking past the front of the car even after it has been off for a while. How can the exhaust be getting to the air intake for the heater?? Help!! I'm being asphyxiated every time I use the car and it's COLD here in Ontario. Thanks for any help.

 

Flex pipe still leaks. Their only a temperature fix.

 

I looked at the flex pipe while the car was up on the hoist and it looked good. How does the exhaust get into the car even if it is the flex pipe?

 

With the engine idling, hold a wadded-up rag against the tailpipe. Not hard enough to stall the engine, but it'll raise the pressure inside the exhaust pipe. Then any leaks will be much easier to hear, like hissing sounds.

Have someone do that while you listen up near the engine.

 

OK I tried that and there is a hissing noise from the front while my head was under the hood. Is there supposed to be a gasket where the pipe joins the manifold?? Could it be leaking there where it joins? The whole front pipe and flex pipe was replaced in one piece so can't figure out where the leak could be from. Still don't understand how it is drawn into the car with the heater fan....

 

The flexible bellows is part of the stock A-pipe. If that's what they replaced, they should have used a new gasket at the front. Shown in the picture as #9 or #10 depending on which 4-cyl engine you have. You don't say whether it's a V6 but that's probably similar.

Normally leaky exhaust goes under the car & the guy behind smells it. But if your cabin-air filter is plugged, maybe it can suck in through the water drain near the AC evaporator.

 

Thanks for the tips. As it turns out, they had used the wrong sized gasket and it was leaking - I could see exhaust billowing out from under the heat shield at the manifold one day when it was -30 celsius. It is now fixed.