How to Replace a Muffler

Several months ago I posted about quick fixes to muffler emergencies. This slows the decline but doesn't solve the problem. So now that it's warm outside again, I decided it was time to replace my failing muffler. I'll be doing this replacement on a Jeep Cherokee. Your car will almost certainly be different. But if you're fairly handy and have some basic tools, this is a job you can easily do yourself. The "discount" muffler store down the street wanted $325 to replace my muffler. I did this job for $105. Repairing your car yourself can save a lot of money!

The first step is to remove the old muffler. Assuming you don't have an acetylene torch, (as I do not), an angle grinder with a metal cutting disk will get the job done. Angle grinders are relatively inexpensive tools and are useful for a wide variety of projects. My muffler is attached to the car by one hanger and by the connection to the catalytic converter. First I'll cut the hanger and remove the hook from the rubber grommet.
Then I'll cut the welds that hold the muffler on the catalytic converter. First I cut the muffler pipe itself and then I cut the piece left on the catalytic converter, which came free easily. The old muffler was now free from the car and easily removed and sent to the metal recycling center.

I borrowed a pipe expanding tool from a freind, but I did not end up needing it. If the catalytic converter outflow pipe had been bent or crushed, this tool can expand the pipe so it fits snugly inside the muffler inflow pipe. I had a snug joint so I didn't need this tool. But if you do not have a snug fit, you can borrow this tool from an auto parts store with a tool rental program.

Now that I have a snug fit, I'll apply muffler joint sealant. With the heat of the engine, this stuff will expand and form a tight joint. You don't want any exhaust gases escaping from the joint! And because I won't be welding this muffler, I need to pay special attention to the joints. Wear gloves when applying this stuff. I have a feeling it's made of nasty chemicals.
Next I'll slide on the new muffler and bolt it down with some automotive U bolts. I'll use two clamps on each joint. Interestingly, the inflow used 2 1/4" inch clamps and the outflow used 2" clamps. Also make sure to reattach the muffler hanger to the rubber grommet.
Since I have a car that had very similar parts for about 15 production years, the parts are easy to find, cheap and custom made. The exhaust pipe was pre-bent and the muffler slides right on with no hassle. And what a difference a new muffler makes! Not only is the car much quieter, but it runs so much smoother. Quick acceleration and drives like new! They always say that a muffler is mandatory not just for sound control but because it provides back-pressure on the engine. You can really tell the difference when you install a new muffler. The car has more power and drives like a dream!