Replacing exhaust sections. Old pipe is "crimped."

[Chapap]

My tail pipe slides into the outlet on the muffler, then secured with a U-bolt thing. The tail pipe rusted off right at the muffler. I managed to remove the tiny section that was stuck inside the muffler outlet. I tried to slide the new pipe in, but the muffler port is "crimped" so it won't just slide in. Is there a way to un-crimp the muffler outlet? Do I just cut it off and do a splice kind of thing?

This is on a Ram with 3" exhaust if that makes a difference.

 

[alwaysFlOoReD]

There are pipe expanders. I bought some from Princess Auto years ago. The couple times I've tried them they didn't work for me. You could try harbor freight and take them back if they don't work good enough.
They look like wedges of metal about 6" long held together with orings. There is a screw thru the center that forces the wedges apart when tightened.

 

[RobbieD]

I've run into the same thing before. I took the too-tight pipe to my local muffler shop. It took him just a minute to throw it on an expander mandrel on one of his machines.

He didn't charge me anything for it; but later on I did take one of my Explorers to him for a muffler, just because of that freebie.

So check the muffler shops around you.

 

[19Walt93]

Muffler clamps used to be 5/16" u bolts and were more than adequate for the job. Most now are 3/8" so it's easy to overtighten them and crush the pipes like you found.

 

[lil_Blue_Ford]

I’ve had mixed success with the pipe expanders mentioned. That’s basically what they are intended for, to flatten the crimps from the clamps so you can replace the bad section. Around here though, unless it’s stainless pipe, it usually doesn’t last long enough to be able to just un-crimp a pipe and slide a new piece in. When I get a project completed to the point where it’s ready for exhaust, I take it up to the local muffler shop (straight up old-school hot-rod muffler shop), tell them stainless, and turn them loose.

 

[pjtoledo]

check loaner tools at a local parts store for the expander, good luck.

a quick look at their selection adapters may give you some options.

 

[Snoranger]

Pipe expanders are almost worthless. The best way to use them is to heat the pipe with a torch and then expand the pipe. (No a propane torch won’t work.)

The second best way to use them is to put pressure on the pipe then go around the circumference and hit it with a small hammer. You’ll need to do this a bunch of times.

The third best way is to get pissed off at it, throw it in the garbage where it belongs and replace the entire exhaust system.

 

[19Walt93]

I have 3 different expanders. I wind up a little tension on the expander, tap around the circumference with a hammer, tighten it some more and repeat. I don't use them often but they save the day when they're needed.

 

[Chapap]

The third best way is to get pissed off at it, throw it in the garbage where it belongs and replace the entire exhaust system.

I was nervous that this would be the rout I'd have to take. I could have cut it off at a straight section in front of the muffler, put in a splice, and replaced everything from there back. Fortunately, I managed to get the expander to work tho. It took a couple tries and some serious torque on the expander (just short of adding a cheater bar). I was amazed when it actually went right tho. No clue how tight the new U bolt is. I tightened it pretty tight tho.

 

[superj]

i have never gotten one of those pipe expanders to work. they just get thrown back in the drawer so much that i am missing pieces now

 

[Chapap]

i have never gotten one of those pipe expanders to work. they just get thrown back in the drawer so much that i am missing pieces now

I imagine that outlet is pretty weak. There was a ~1/2" cut on the bottom, and I could bend that corner with my fingers. further in it was more robust, but it's definitely a 28 year old pipe.

Why do exhaust systems get so rusty? Is it the heat? Some chemical reaction with the exhaust? Cheap coatings? That and the drive shaft always seem to be the rustiest things under the car.

 

[superj]

i have no idea but i guess its just the metal make up used?

 

[RobbieD]

Why do exhaust systems get so rusty? Is it the heat? Some chemical reaction with the exhaust?

Hot exhaust, you shut it down in cold, moist air and you get a lot of condensation. Exhaust doesn't help either; it's nasty stuff.

I'm convinced, though, that exhaust systems mainly rust so bad, is because they're a particular bitch to work on.

 

[Chapap]

Another question but related enough. I'm going to replace my cat. On one side, I can cut the cat tube and "unwrap" it from the muffler inlet. On the other side, the pipe that I'm removing is inside the upstream pipe (just like what I already did). Previously, the pipe rusted off at this joint and I just had to remove the remaining 2-3" of pipe stuck inside the muffler outlet. That was a bear of a job... lots of happer and chisel work to get that pipe crushed and separated from the muffler outlet. Ideally, I'd replicate this process again, but I don't think it'd be worth the extra hassle just to keep the system completely stock. I can get around all that by adding a splice of sorts. Is that the best way to go? It looks like the system was designed so all the joint openings point backwards (the female side is always on the front of the car), I guess to reduce water splash getting in. Is it worth trying to keep this setup or should I just cut it off and make it work?