'99 XJ -- questions about exhaust system - JeepForum.com
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post #1 of 17 Old 09-17-2019, 07:23 PM Thread Starter
Davy A
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'99 XJ -- questions about exhaust system

While driving home from work last week, I suddenly heard a dragging sound. I pulled over, and found that the joint between the catalytic converter and the muffler had rusted through, allowing the muffler to drop.

I've done exhaust replacement on other vehicles years ago, and at least at first glance, looks like I could maybe tackle the project on the Cherokee.

One thing I noticed is that the exhaust system components are suspended by support rods welded to the various pipe sections, and these rods are pushed into rubber insulators, instead of being held up by hangers, as I've dealt with on other vehicles. I noticed that the replacement pipes have these same rods attached to them.

So, my first question is about the rubber insulators. When I'm ready to remove the old pipes, do I just use a hammer to drive the rod out of the rubber?

Another thing...in the service manual for the Cherokee, it says that in order to remove the front exhaust pipe, you should first support the transmission, then remove the crossmember. But it looks to me like there would be enough room above the crossmember to just pull the pipe through, after removing the flange from the exhaust manifold. Would surely be a lot easier. Anyone have any experience with this? Thanks.

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post #2 of 17 Old 09-18-2019, 04:35 AM
CJ7-Tim
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The hanger rods just slip out of the rubber hangers. Add a squirt of WD-40 if necessary. I sure would try wiggling the pipes into place before I would try snapping off the rusty crossmember bolts. The late model down pipe and crossover are stainless steel and likely do not need replacement. A new cat converter and exhaust from the cat to the rear bumper is all you should need.

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post #3 of 17 Old 09-18-2019, 07:54 PM Thread Starter
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Originally Posted by CJ7-Tim View Post
The hanger rods just slip out of the rubber hangers. Add a squirt of WD-40 if necessary. I sure would try wiggling the pipes into place before I would try snapping off the rusty crossmember bolts. The late model down pipe and crossover are stainless steel and likely do not need replacement. A new cat converter and exhaust from the cat to the rear bumper is all you should need.
Thanks for the response! I was considering keeping the front pipe up to the catalytic converter, since it seems pretty solid. Is it possible that some of those were not stainless? On mine, it seems to be the same color and texture as the catalytic converter. I've attached a photo of the connection where they meet. If I do want to try to save the exhaust pipe, I guess a chisel would work to peel the inlet of the converter from outside the end of the front pipe. Or is there a better method?

One reason I was considering replacing the front pipe is because I found a rather deep dent in the pipe, just below the flange where it meets the manifold. I've attached a photo (though not a very clear one). I have no idea how it got there...it didn't happen in the time I've owned the Jeep, well over ten years. I'm wondering if this could restrict the exhaust enough to create back pressure (I haven't noticed any performance issues).

Any ideas welcome!
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post #4 of 17 Old 09-19-2019, 04:30 AM
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The dent is designed to be there, every later model XJ has one. A common opinion is that it doesn't hurt anything and is there for a reason. I can't remember if I used an air chisel or had to slit the tube on the cat with a grinder. Maybe it was some of each. The pipes are some type of stainless, all three of my XJ's still have the original down tube with dent and the original crossover tube.

.

A recent Gallup public opinion poll shows the NRA, at 58% approval, has a higher approval rating than either Hillary Clinton or Barack Obama.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ...

Originally Posted by Ronald W. Reagan: Government is not the solution to our problems; Government is the problem.
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post #5 of 17 Old 09-21-2019, 02:06 AM Thread Starter
Davy A
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Originally Posted by CJ7-Tim View Post
The dent is designed to be there, every later model XJ has one. A common opinion is that it doesn't hurt anything and is there for a reason. I can't remember if I used an air chisel or had to slit the tube on the cat with a grinder. Maybe it was some of each. The pipes are some type of stainless, all three of my XJ's still have the original down tube with dent and the original crossover tube.

It took a bit of time and effort, but using some "old school" tools (a muffler removal tool and a chisel), I was able to peel back the inlet coupling of the catalytic converter, and remove it from the exhaust pipe.

You were 100% correct about the pipe. As can be seen in the photo, it is every bit as solid as the day it was installed. Glad you mentioned that...saved me the trouble and expense of replacing some perfectly good pipes.

Now, I'll get the cat, muffler, and tailpipe ordered, and should be a pretty straightforward process after that. One thing I noticed about the tailpipe -- the very back end of the replacement tailpipe has one of the rod-type hangers welded onto it, but on the original, the back hanger is more of a traditional type, with an exhaust clamp holding the tailpipe to the hanger. No big deal -- I can cut the rod hanger off of the new pipe, and attach it like the old one was. I guess the design was changed slightly over different model years.
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post #6 of 17 Old 09-21-2019, 05:39 AM
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Originally Posted by Davy A View Post
One thing I noticed about the tailpipe -- the very back end of the replacement tailpipe has one of the rod-type hangers welded onto it, but on the original, the back hanger is more of a traditional type, with an exhaust clamp holding the tailpipe to the hanger. No big deal -- I can cut the rod hanger off of the new pipe, and attach it like the old one was. I guess the design was changed slightly over different model years.
You are supposed to cut that off for your Jeep. It probably said so somewhere in the description from wherever you got it from.
Fits multiple years that attach differently. If I am not mistaken that tailpipe fits all XJ's.
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post #7 of 17 Old 09-21-2019, 06:55 AM
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I have seen two types of factory exhaust hangers at the gas tank area and lots of aftermarket universal and Bubba done-it solutions. My local Fleet and Farm store has a bunch of universal hangers. My cat back exhaust from Iron Rock Offroad came with bent stock like rods that were welded to standard muffler clamps so you can locate and angle them as needed. You could easily fab the same thing.

I used this one that can twist 360* and pivot also.
.
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.

A recent Gallup public opinion poll shows the NRA, at 58% approval, has a higher approval rating than either Hillary Clinton or Barack Obama.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ...

Originally Posted by Ronald W. Reagan: Government is not the solution to our problems; Government is the problem.
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post #8 of 17 Old 09-21-2019, 07:52 AM
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Originally Posted by CJ7-Tim View Post
I have seen two types of factory exhaust hangers at the gas tank area and lots of aftermarket universal and Bubba done-it solutions. My local Fleet and Farm store has a bunch of universal hangers. My cat back exhaust from Iron Rock Offroad came with bent stock like rods that were welded to standard muffler clamps so you can locate and angle them as needed. You could easily fab the same thing.

I used this one that can twist 360* and pivot also.
.
Yeah if the tail pipe hanger is all FUBAR then might be easier to fab something up like CJ7-Tim said.
Cause this was the factory hanger on my '00.

https://www.napaonline.com/en/p/EXP3...xhaust+hangers

It attaches to the nutstrip inside the uni-body. When I did my exhaust it was all messed up. And if things get real messy you have to take off the bumper to get at the nutstrip.
Lucky for me I decided to hang my gas skid at the same time as doing the exhaust. So I removed the bumper, installed new nutstrips, hung the skid, then the new hanger I purchased.
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post #9 of 17 Old 09-21-2019, 10:50 PM Thread Starter
Davy A
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Below is a photo of the replacement pipe, showing the mounting rods, and a diagram of the exhaust system. It does mention that, if unused, the rear tailpipe bracket can be cut off, which would apply in my case. The diagram also shows the hanger to be used in the back is the same type that Ralph77 mentioned.

I've attached a couple of photos of the existing rear bracket on mine (sorry the one photo is fuzzy). I think I can reuse it by removing the existing clamp. I'm not sure, but there may be a spot weld between the bottom of the hook of the hanger and the tailpipe, but I could probably cut through the weld, and then install the new pipe with a new clamp attached to the L-shaped bracket.
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post #10 of 17 Old 09-22-2019, 01:17 AM
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Just take the muffler clamp off. Should not be welded in any way.
On mine that lip that the clamp secures the tailpipe to rotted away.
So I had to buy a new hanger.
Want to say that yours looks intact.
Check the rubber part to see if it is still usable.
Cracking, ripped, dry rotted, etc.
If you can avoid replacing it that will help you avoid a new set up problems.
Cause if the bolts are frozen then you have to cut them off.
Then cause the remainder of the bolt is still in the nutstrip that is when you will have to
remove the bumper to get the nutstrip out and most likely will have to replace it.
Why if it gets to this point fabbing up a hanger using a universal type one might be easier.
Now I would go through all that trouble.
But that is just me.
OCD is a *****. LOL.
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post #11 of 17 Old 09-22-2019, 01:39 AM
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One last thing. I purchased a Walker Quiet Flow for my XJ. Comes with a lifetime warranty.
So remember the fun you had getting the cat off the down pipe?
To maybe avoid that I used this type of clamp for the muffler to tailpipe.

https://www.napaonline.com/en/p/BK_7333972

Now I don't know why it says it does not work with my '00 on that page.
That is the number on the receipt I found in my files so pretty sure it is the one I used.

Point being since this might not crush the tailpipe and muffler together like a traditional clamp
if I ever have to warranty the muffler maybe I can separate them and not have to buy a new tailpipe.
Maybe.
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post #12 of 17 Old 09-23-2019, 11:10 PM Thread Starter
Davy A
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Originally Posted by Ralph77 View Post
One last thing. I purchased a Walker Quiet Flow for my XJ. Comes with a lifetime warranty.
So remember the fun you had getting the cat off the down pipe?
To maybe avoid that I used this type of clamp for the muffler to tailpipe.

https://www.napaonline.com/en/p/BK_7333972

Now I don't know why it says it does not work with my '00 on that page.
That is the number on the receipt I found in my files so pretty sure it is the one I used.

Point being since this might not crush the tailpipe and muffler together like a traditional clamp
if I ever have to warranty the muffler maybe I can separate them and not have to buy a new tailpipe.
Maybe.
That type of clamp looks good, and probably worth its cost, if it makes future disassembly easier. The NAPA site indicates it doesn't fit the '99, either, though I would think it would fit any exhaust pipes of the correct diameter. I wonder if it comes in other sizes, too. Did you also use one at the cat/muffler connection, too? Seems like it would be a good idea to use at all connections.

Also, I've seen some mufflers and tailpipes made of 409 stainless steel available for the Cherokee, instead of the standard steel stuff. I'm considering giving it a try this time around, since I haven't bought any of the replacement materials yet.
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post #13 of 17 Old 09-24-2019, 01:34 AM
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Originally Posted by Davy A View Post
That type of clamp looks good, and probably worth its cost, if it makes future disassembly easier. The NAPA site indicates it doesn't fit the '99, either, though I would think it would fit any exhaust pipes of the correct diameter. I wonder if it comes in other sizes, too. Did you also use one at the cat/muffler connection, too? Seems like it would be a good idea to use at all connections.

Also, I've seen some mufflers and tailpipes made of 409 stainless steel available for the Cherokee, instead of the standard steel stuff. I'm considering giving it a try this time around, since I haven't bought any of the replacement materials yet.
It does come in other sizes.
Now would it make future disassembly easier?
Won't know till I try. Which will hopefully be never. LOL.

I did not think to tell you to use one for the cat/muffler connection but sure I would if I were you.

I did not think to cause an '00 is set up different then your '99. Not all the exhaust slips on together. The rear cat, CA Emission '00's have 2 cats (front and rear), has flanges front and rear. The muffler has a flange on the front. So it is just bolts. The only slip on pieces on my exhaust are rear of the muffler to the tail pipe.

For awhile I was thinking about doing a "performance" cat back exhaust. Muffler and tail pipe. Was looking at the MagnaFlows and the Borlas. One thing I noticed is that MagnaFlow is 409 and Borla was 304. Googling around it appears 304 is better stainless.

In the end I could not really justify the price so I just replaced everything with Walker parts. Why I did go with the QuietFlow for the muffler cause of the lifetime warranty.
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post #14 of 17 Old 09-29-2019, 01:52 AM Thread Starter
Davy A
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Originally Posted by Ralph77 View Post
One last thing. I purchased a Walker Quiet Flow for my XJ. Comes with a lifetime warranty.
So remember the fun you had getting the cat off the down pipe?
To maybe avoid that I used this type of clamp for the muffler to tailpipe.

https://www.napaonline.com/en/p/BK_7333972

Now I don't know why it says it does not work with my '00 on that page.
That is the number on the receipt I found in my files so pretty sure it is the one I used.

Point being since this might not crush the tailpipe and muffler together like a traditional clamp
if I ever have to warranty the muffler maybe I can separate them and not have to buy a new tailpipe.
Maybe.

Because of some other issues that cropped up, I temporarily put the exhaust replacement on the back burner, which is good, because I am thinking that putting the band type of clamp (like the one you used) on all of the exhaust connections.

The one from NAPA you used on the muffler to tailpipe connection (2 1/4") would probably be the correct one for mine as well, since the Walker diagram shows that a standard 2 1/4" clamp should be used there.

The diagram also calls for a 2 1/4" clamp at the cat to muffler connection, too, so I would imagine the 2 1/4" band type clamp would work there, too. In fact, I found this 2-pack of that size in stainless steel on eBay:

https://www.ebay.com/itm/2-Pack-2-25...AAAOSwZvlc9-4t

The Walker diagram shows a 2 1/2" standard clamp at the front pipe to cat connection, so I'm assuming a 2 1/2" band type would work there:

https://www.ebay.com/itm/2-5-2-1-2-Stainless-Steel-Lap-Joint-Band-Clamp-T-304-Stainless-Steel/282755573884?hash=item41d58ba87c:gRMAAOSw~llcIc6 L

I noticed that these items on eBay are called "lap joint" clamps, which I guess is because the smaller pipe fits into the larger pipe, and so the clamp has a "step" in it, to overlap both pipe sizes. (I have also seen "butt joint" clamps, which I assume would be used in cases where two pipes of the same diameter are to be joined, which does not apply in my case.)

I can definitely see the advantage of the band type clamps, to make future disassembly easier!
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post #15 of 17 Old 09-29-2019, 02:07 AM
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Those Ebay ones look pretty good. My Napa one says Aluminized Steel. The Ebay ones are stainless and the 304 type. Which like I said earlier I believe to be the better stainless.

I am thinking what you are calling butt joint clamps might be what I refer to as band clamps. But not sure.

https://www.napaonline.com/en/p/BK_7335978

Frankly when I was doing the exhaust I was just going to use a traditional muffler clamp. Then my store manager/friend said no use the step kind instead.
Looking at it I saw the possible advantages of them. He is an excellent auto part store counter guy but also a very good mechanic. He is one of those guys that when he talks you listen and pretty much do what he tells you. LOL.

Now will this make future disassembly easier?
Not a clue but I hope so.
You have to realize those pipes still slip into each other. Heat alone will "weld" those two pipes together.
But we can hope for the best if and when.
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