TJ Exhaust Odors

shawn

shawn

running dog lackey of the oppressor class
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Mar 13, 2005
Location
Raleigh, NC
To what extent is it considered "normal" to get exhaust fumes in the cab of a TJ?

Ours has a stock-style exhaust that exits in the normal place. It's cut a bit short now, but when we got it, it had an extended tip with a turn-down. Changing the exhaust hasn't changed the amount of fumes in the cab.

If the windows are rolled up and the top is on, little/no fumes get in. Maybe a whiff once in a while, but no big deal.

If one front window is down (even a little), lots of fumes in stop/go. Need to roll both windows all the way down and possibly turn on the fan, depending on how much stop/go, etc.

The soft top is about as tight as can be expected. There are gaps, but there are always going to be gaps.

The tailgate, however, is bent, and doesn't close very tightly. It is definitely not tight against the weather seal all the way around, so I'm guessing this is where a lot of the fumes are coming in.... but I don't want to go to the trouble of replacing the tailgate if the above behavior is "normal" in any way.

Thoughts?
 
I cut my TJ exhaust off just behind the axle and I don't notice any fumes with the windows down.

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You shouldnt be getting any fumes if the exhaust is stock or mostly stock/cut off just a few inches. I had mine cut off right before the rear axle and never had any fumes whether the windows were open or not.
 
My exhaust is cut and turn down 45deg at the end of the muffler into the rear axle and I get a decent amount in too, but it's never been unbearable.

Having the back cracked open and the drain holes open always rushes flow into it but I'm willing to bet your getting a crack in your exhaust manifold as well.

Did you check the manifold to see how it's going? Your's is a pre '99 right? I've been through 3 and the only one that's held is the OEM with the flex pipe.

http://m.autozone.com/autozone-mobi...WD/Exhaust-Manifold/_/N-jdmiaZ9iy4i?id=274821


I tried Rock Auto first and they sent me one that did not fit. (Tolerance thickness on the flange was wrong) The autozone fit perfect.
 
Mine was cracked so bad I had to ride with all the windows down or i would get a headache/drunk sleepy feeling. I replaced it with an oem style stainless with flex pipes I got on ebay for $85 bucks shipped. Works great
 
EdJonesJeeper said:
My exhaust is cut and turn down 45deg at the end of the muffler into the rear axle and I get a decent amount in too, but it's never been unbearable.

Having the back cracked open and the drain holes open always rushes flow into it but I'm willing to bet your getting a crack in your exhaust manifold as well.

Did you check the manifold to see how it's going? Your's is a pre '99 right? I've been through 3 and the only one that's held is the OEM with the flex pipe.

http://m.autozone.com/autozone-mobi...WD/Exhaust-Manifold/_/N-jdmiaZ9iy4i?id=274821


I tried Rock Auto first and they sent me one that did not fit. (Tolerance thickness on the flange was wrong) The autozone fit perfect.
Click to expand...

It's done it with both motors, including the old one right after the manifold got fixed. This manifold looked good when it went in... Exhaust issues were unchanged.
 
No experience with a TJ, but I could see fumes possibly getting sucked through your non-sealing tailgate when the windows are cracked. I'm thinking the air rushing passed the cracked windows is creating a low pressure in the cab, and it is pulling air in from any hole/gap. Could you stuff a towel or something into the tailgate gap and seal it up good as a test?

When I use to drive my Samurai on the road many years ago, I noticed higher level of fumes after I cut my tail pipe off from it being damaged. I then bought a new clamp on extension to turn it out to the side behind the rear tire. It seems getting the exhaust out into the air flow down the side of the vehicle helped rather than dumping it straight out the back under the rear bumper.

Hope that helps. That problem can be very annoying.
 
shawn said:
To what extent is it considered "normal" to get exhaust fumes in the cab of a TJ?

Ours has a stock-style exhaust that exits in the normal place. It's cut a bit short now, but when we got it, it had an extended tip with a turn-down. Changing the exhaust hasn't changed the amount of fumes in the cab.

If the windows are rolled up and the top is on, little/no fumes get in. Maybe a whiff once in a while, but no big deal.

If one front window is down (even a little), lots of fumes in stop/go. Need to roll both windows all the way down and possibly turn on the fan, depending on how much stop/go, etc.

The soft top is about as tight as can be expected. There are gaps, but there are always going to be gaps.

The tailgate, however, is bent, and doesn't close very tightly. It is definitely not tight against the weather seal all the way around, so I'm guessing this is where a lot of the fumes are coming in.... but I don't want to go to the trouble of replacing the tailgate if the above behavior is "normal" in any way.

Thoughts?
Click to expand...



Sounds exactly like mine, but my exhaust ends before the axle. I was actually thinking of getting the tube extended back to or near the original exit to reduce the fumes for the moab road trip next year but for driving around here its been no issue for me, I'm use to old crusty cars with bugkiller exhausts. I was also going to look at my manifold and exhaust pipe connection because I think it might have been damaged over the past couple of years for various reasons and you might want to make sure none of yours are loose or have cracked or bent since the engine install.
 
Did u buy it from a car lot? If so look for jb weld painted to cover up rust holes near exhaust
 
My guess is tailgate, if rear window was cracked in my old bronco fumes were horrid
 
On my 72 rag top Blazer, I changed the dual exhaust from rear exit to side exit behind the rear tires and the problem went away. I would say the tail gate and rear exit (if it is) are the right data points. Behind the tail gate is a low pressure area where air just swirls and looks for a place to go.
 
I'm going to stuff a wet towel in the tailgate, see what that gets me.
 
This thread is in the wrong section, mods please delete
 
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