1971 Duster exhaust smell in cabin after new muffler and tail pipe

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adam83

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Hello all,

My 71 slant six duster's muffler was noisy, buzzing and rotted through, so I took it to a local exhaust shop to get it replaced.

They replaced the muffler and tail pipe. I paid and left. Within a couple miles the air in the cabin felt stuffy, thick and my nasal passages started swelling. I thought maybe the car in front of me had exhaust leak. Long after I passed him I still felt like the cabin had a low but constant volume of exhaust making me feel sick. I took someone else for a ride, they smelled exhaust too. Windows up or down.

I looked underneath the car and noticed the end of the new tail pipe looks like it's at a different angle than the original pipe, like it doesn't have the same curve. It also seems like it's tucked under the car more, and doesn't extended out towards the bumper as far as the original did.

Can someone confirm or post a picture of where the stock pipe ends? My suspicion is that my new tail pipe is not long enough, and/or not curved toward ground enough, and exhaust is being pulled back into car.

This was not happening before I had the work done. And currently I don't hear any audible leak, so that's why I'm focused on the tail pipe theory. Also, my exhaust manifold heat control valve is frozen, but I don't see how that could cause an exhaust leak into cabin.


Here's a pic of new pipe


20220708-173420.jpg


20220708-173348.jpg
 
That's not right. The end of the pipe needs to be at least even with the bottom of the bumper, if not a little past it.
 
They didn't even feel like de-burring the cut? Geez. This is a great example of why I do everything myself on my cars.

Maybe try taking it back and have them fix it.
 
I would damn sure take that "shoddy" work back to the "jack leg" that did it. That is just so wrong to do something like that and give it back to the customer...and get paid for it to boot! :mad:
 
Also, ANY leaks into the body ANYWHERE can suck in exhaust. If you ever notice when you drive, parts of the rear of the car get dirty, especially when raining, as there is a vacuum formed at certain places. The trunk, quarters, floor pan, ANY hole(s) into the body. Trunk gasket, etc.
 
Yup, two problems. One, that tailpipe is too short and a shoddy job. Second, you’ve got a hole somewhere- floor/trunk pan plug, trunk gasket, heck even tail light gasket or rust hole that’s letting exhaust in.

I’d absolutely take it back and tell them to fix the tailpipe because it’s causing exhaust to get into the cabin, which is a new problem related to their fix. After they sort out the tailpipe, give your plugs/gaskets/seals a once over and see if you can find the entrance point.
 
The more I look at the tail pipe, the more it looks like it was lazily cut with a plasma torch! Irritating. I will definitely ask them to clean that up at the very least.

I looked up some pictures of slant six a bodies. Not many with exhaust pics, but the ones I found do show the pipe reaching further out. Im going to ask them to fix that. The only problem is, I dont have any pics of mine before they touched it, so i cannot confirm if my original was correct either.. hopefully they dont fight me on it.

Duster-1098.jpg

making-slant-six-sense-22.jpg
 
I snapped some pics from underneath while they had it on lift. Looks like I have a couple floor pan plugs missing

20220708-155759.jpg
 
Yeah they just torched the end off. It also looks like they put that pipe right up against your leaf spring shackle too.

Like I said, I’d take it back. The treatment on that exhaust tip is just lazy. And yeah, if you weren’t getting fumes in the car before and you are now, that’s on them.

But you should also replace those floor plugs.
 
Hello all,

My 71 slant six duster's muffler was noisy, buzzing and rotted through, so I took it to a local exhaust shop to get it replaced.

They replaced the muffler and tail pipe. I paid and left. Within a couple miles the air in the cabin felt stuffy, thick and my nasal passages started swelling. I thought maybe the car in front of me had exhaust leak. Long after I passed him I still felt like the cabin had a low but constant volume of exhaust making me feel sick. I took someone else for a ride, they smelled exhaust too. Windows up or down.

I looked underneath the car and noticed the end of the new tail pipe looks like it's at a different angle than the original pipe, like it doesn't have the same curve. It also seems like it's tucked under the car more, and doesn't extended out towards the bumper as far as the original did.

Can someone confirm or post a picture of where the stock pipe ends? My suspicion is that my new tail pipe is not long enough, and/or not curved toward ground enough, and exhaust is being pulled back into car.


This was not happening before I had the work done. And currently I don't hear any audible leak, so that's why I'm focused on the tail pipe theory. Also, my exhaust manifold heat control valve is frozen, but I don't see how that could cause an exhaust leak into cabin.


Here's a pic of new pipe


View attachment 1715953211

View attachment 1715953212

Wow, that needs to be 6" longer. (that's what she said) and plug those open holes.
 
Like said, pipe should be a little longer and YOU do not need holes in the floor especially with the pipe where it is.
I bet you paid the guy enough to have done it right!
 
Ok, I went back to the shop. They extended the pipe and cleaned up the end. I'm not thrilled that there's another weld in the pipe now, but they didnt argue with me about fixing it, it's not a performance exhaust, its functioning correctly and theres no leaks so ill live with it.. Definitely never gonna go back though!

20220709-151602.jpg

20220709-151556.jpg

20220709-151455.jpg
 
Thanks for all the opinions and advice!

I'm ordering a body plug set, and body gasket set from Detroit muscle technologies as well
 
You need to buy a universal tail pipe hanger while you are at it. Too much pipe without a hanger, even before the extension. However, I did go back and look, I believe there is a hanger that can be seen in one of the pics.
 
Yes there is a hanger on the rail about 4" behind the area of the leaf spring perch
 
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