Need advice and ideas on exhaust fumes!

[78Malibu496bbc]

hello, and good evening. i have a 78 malibu 4 dr. ive been having issues with exhaust fumes filling the cab. ive had the car to several reputable exhaust shops and performance shops. car has hooker headers. when i first built the car, i had 3 inch straight pipes dumped right before the rear end, and the fumes convinced me, that the i needed longer pipes. i decided to go with 3 inch pipe to the rear bumper, and hooker electric cutouts right before the rear end. after a few drives, still noticed that the cab was fumy.l checked the cutouts and had no leaks. after that, i knew it just had to be the headers somewhere. 5 exhaust shops/ 3 performance shops appointments later, its still doing it. no one can explain it. We even went to the extreme of thinking that maybe it was the fuel cell we had installed. So we went back with a new factory tank, and lord behold, still darn thing. any advice or suggestions would be appreciated. after paying for 3 full exhaust systems, from header gaskets to tip, im completely at a loss lol.

 

[Built6spdMCSS]

Did the fumes get you that high to pay for "3 full exhaust systems, from header gaskets to tip"?

Is it an exhaust smell or gas smell?

 

[pagrunt]

There might also be a rusted floor problem that might be allow the fumes to enter the car. Make sure everything is good on the underside while fixing the pipe leaks.

 

[Built6spdMCSS]

Same thing I was thinking but with 5 different shops they would have seen that..

 

[78Malibu496bbc]

Did the fumes get you that high to pay for "3 full exhaust systems, from header gaskets to tip"?

Is it an exhaust smell or gas smell

Did the fumes get you that high to pay for "3 full exhaust systems, from header gaskets to tip"?

Is it an exhaust smell or gas smell?

Lol i had most of everything for the 3 different setups ive tried. its for sure exhaust fumes.

 

[78Malibu496bbc]

There might also be a rusted floor problem that might be allow the fumes to enter the car. Make sure everything is good on the underside while fixing the pipe leaks.

So in the beginning, i thought the same exact thing. i pulled up the carpet and patched up all holes, and sealed everything. helped some, but the majority was still there.

 

[78Malibu496bbc]

Same thing I was thinking but with 5 different shops they would have seen that..

exactly. ive never had an issue like this before. ive never had several exhaust shops look at me, and say, "we smell it too, But have no idea where it could be coming from. "

 

[Built6spdMCSS]

Header to Head sealing up good?

I'm assuming it's a 496 in the car given the screen name..

 

[Bar50]

What headers?

2241 or 2455?

Windows up?

Windows down?

Heat or a/c?

How does the exhaust exit the body?

 

[airboatgreg]

The problem with running exhaust out the back is that when you are moving you create a draft that pulls exhaust back to the car. Check deck lid gaskets, rear light sealing, rust etc.