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Discussion Starter #1
Backstory: A few weeks ago I noticed a rattle develop under the jeep. Last week I experienced a noticeable lack of power up hill (the hill I drive everyday to work) and have since stopped driving it until I get a fix.

This morning I finally got underneath to check it out. On visual inspection all exhaust connections and mounts appear solid. After starting it, I couldn't find exhaust leaks, but I did follow the rattling noise to inside the muffler. I could dampen the rattle by pressing on the end of the muffler. Could a bad muffler also restrict air enough to notice lack of power?

I'm debating to either do the work myself or take it to a shop. I don't own a torch, or have any exhaust experience, so that would add to the cost of doing it myself. Any budget recommendations to add to a jeepers toolbox? Would a cheap torch like this be adequate for the job?

The quote I got from a local exhaust shop was about $145 for muffler only (vs about 45-75 to do it myself). What's with the large price disparity between a $30 muffler and a $65 muffler on rock auto? I think this is the only part that NEEDS to be replaced, should I consider doing more? Is getting a professional inspection or professional installation likely to be worth it?
 

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Rusty bolts/nuts can be challenging and after all the cursing, rocking and hammering is done some other parts of the rusty connections will probably be ready to fail. If Rock Auto has the exhaust system available perhaps you can be successful. Can't hurt to attempt the DIY as the local shop is nearby. Quality differences between mufflers are usually the price difference explanations.
 

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I have had a clogged catalytic converter kill power to the point of no movement. Never had a muffler do that but its possible.
 

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Yep. Mine did the same thing a few months ago. The muffler had come apart inside the housing. Replaced it and all is good in the galaxy again. I actually have more power now than ever.
 

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I believe I have the same rattling noise from the guts of the muffler and mostly hear when idling. Will try to check with leather gloves on to see if that seems to be where the rattling is coming from.Funny that after replacing the old 11 body mounts and removing the 2" body lift, this YJ sounded so much better without all the crunching and groaning.Hey, It's a old jeep.:drinks:

I'm thinking to hit up a close by muffler shop.:)
 

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I Had the exact same issue with rattle while idling and also when I started moving at low RPM. I also heard the rattle when I cut the engine off. The catalytic converter had completely come apart on the inside over time.
I had a local muffler shop remove the cat. Converter and run a straight pipe in its place. I had a Flowmaster delta Flow 50 muffler installed at the same time. It got rid of my rattle and it also sounds much better while driving with the new exhaust. Total cost (including. Muffler) was like $200
 

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For me, I'd replace the muffler and tailpipe at the same time, and I'd do the job myself, rather than paying a muffler shop to do so.
I actually did replace my muffler/tailpipe and here's how. It's not all that difficult.

1- Gather together the muffler, tailpipe, hangers (3?) and clamps (2). Compare them to what's already on your Jeep to insure you have all the correct parts and hardware.

2- Jack up the rear of the Jeep and support it on jackstands. Remove the right rear tire.

3- With a hacksaw, cut the front muffler pipe close to the body of the muffler. Take a look at your new muffler to see how and where it attaches to the pipe off the back of the cat.
A 6cyl. muffler attaches close to the cat and a 4cyl. muffler should have a length of pipe between the cat and the muffler.
Cut the old tailpipe off behind the muffler and remove both parts along with the rubber donuts that the tailpipe hangs from.
It might be easier to remove the old tailpipe and install the new tailpipe if you disconnect the right rear shackle and allow the axle to drop a bit.

4- Depending on how much distance belongs between your muffler & cat, cut the old pipe that's still sticking off the back of the cat to the proper length. If your Jeep has had the muffler replaced in the past (most likely), you may simply have to chisel the front of the old muffler pipe off the cat pipe.
Now is a good time to bang on the cat to see if there is anything loose inside. If there is, replace the cat along with the muffler/tailpipe.

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If you have to replace the cat, insert replace cat instructions here
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5- Slip the new muffler onto the pipe that comes off the cat. Make sure that the new muffler goes onto the cat pipe at least as far as the old muffler did. Slip the tailpipe onto the rear muffler pipe (you may need to pound on the rear of the muffler with a mallet to push it far enough onto the cat pipe) Now, hang the new donuts on the hangars off the tub and onto the hangars of the pipe. A bit of dish soap can make this easier. Make sure the tailpipe is far enough onto the muffler outlet pipe. Put the new clamps on the inlet and outlet of the muffler so that the clamps will compress the muffler in pipe onto the cat outlet pipe and the tailpipe inlet well onto the muffler outlet pipe. Just run the nuts up finger tight.

6- Inspect the muffler and tailpipe for a good fit. The tailpipe will seem kind of close to the crossmember over the axle. Just make sure that if you grab it and shake it that the tailpipe won't hit the crossmember.
Once you're satisfied that all is as it should be, tighten the clamps at the front and rear of the muffler. If you've dropped the axle, replace the axle onto the shackle and tighten the nuts only finger tight for the moment. Replace the wheel and put the Jeep down on the floor.
Now, tighten the shackle nuts to 95 ft. lbs.

7- Start the Jeep and listen for exhaust leaks and contact with the body.

A good tailpipe should be around $30.00.
A $110.00 muffler claims to last 3 times longer than a $40.00 muffler at NAPA.
I guess it depends on how much your budget can stand and how long you plan on keeping your Jeep.

With any muffler, if you drive the vehicle long enough on each trip to evaporate all the condensation that forms upon start up, the muffler will last way longer than many short trips that leaves condensation inside the muffler to cause rust and corrosion.
If you have a short commute, the muffler won't last as long as it might if you have a long commute.

Other posters may have more info to add to this.

Good Luck, L.M.
 
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Discussion Starter #9
Thanks Lucky Mac, and all. I've got parts on order do the muffler and tailpipe my self. From what I can tell both are original equipment because there is no clamp rear of the muffler (the tailpipe is directly welded to the muffler)
 

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By the way that is a nice little torch {I have one, and an Ox/Acc rig} to have around the house, to heat some things, but it is not what is used to weld pipes and do exhaust work, you way be able to solder tubing joints with it or heat a bearing, but not weld or use for cutting steel.
 

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Discussion Starter #11
Update:
Damn that muffler was a pita to get off. But I did discover why it was rattling! It had pieces of the catalytic converter inside. So now I'm waiting for more parts, new cat and front exhaust pipe should be here this week.
Description of failure: When the muffler came off I found a couple pieces about 1 cubic in. each of the white honey comb material, looked inside and saw 1 more inside the cat, which appeared to be only about half full of functional material.
The service manual states the catalytic converter is built to last the life of the vehicle. But it did last 22 years... Is cat failure a relatively normal thing or should I be looking upstream for a reason the cat failed?
 

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Discussion Starter #13
Emissions testing where I live.
 

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A decent cat like a Magnaflow or a Walker should last another 20 years or maybe even a couple hundred thousand miles.

When these vehicles were built I don't think Jeep intended for them to last this long.
If you were the original owner, perhaps you could ask MOPAR for a new cat under warranty. I wonder what federal emissions regulations are on that point?

Good Luck, L.M.
 
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I think all emissions back the were covered for 5 years or 50K, which came first.
 

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Discussion Starter #16
Got it all put back together today. Assembly was a breeze. I'm glad I did it myself, but it sure took way longer than expected because of difficulty removing the muffler then discover I need more parts.
 

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Got it all put back together today. Assembly was a breeze. I'm glad I did it myself, but it sure took way longer than expected because of difficulty removing the muffler then discover I need more parts.
You chose the perfect day to work on your Jeep. I was out and about in my shirtsleeves. I might have wanted to be wearing an old sweatshirt if I was laying on the ground working under my Jeep though.
My outdoor thermometer recorded a high of 63* here in Elizabeth.

Discovering that you need more parts is just a thing if you work on automobiles. I've been in the car business for over 50 years and it happens to me regularly.

Good Luck, L.M.
 
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