installing exhaust

[5spd_xj]

hey, i got my rusty's cat back yesterday.... just wondering what exactly is involved with installing it? i've never done anything with my exhaust before, so anything will be helpful... thanks in advance, and btw, i have a 95 with the 4.0 and ax15

[scorpio_vette]

most important tool if you don't already have it, is a torch. if you don't have one, you can get a small one at the hardware store. you'll need 1 oxygen tank, and 1 acetylene (don't remember how it's spelled) tank. then they should have a torch setup that connects to both of the tanks with a valve at each tank so you can mix the flow of the 2 gases.

then you heat up the nut until it's glowing orange, and then the bolts will turn right out without breaking anything.

that's pretty much the hardest part. the rest is just a matter of holding up the new one and attaching the hangers.

[5spd_xj]

alright, is there any welding involved? or do i just use clamps or what? thanks for the quick reply, i appreciate it !

[goodburbon]

You spelled it correctly.


then you heat up the nut until it's glowing orange, and then the bolts will turn right out without breaking anything.

If you're going to all that trouble why not just torch off the old u-bolts and get new ones?

[goodburbon]

You can/should do both if you have a torch, and with a torch you can easily just braze the pipes together not arc-weld.

[ridinhigh07]

i just got mine installed at Meineke for $100. My exhaust was hangin so low cause one of the bolts broke and so did the rubber mounts. It took like 30 mins for them to do it and it sounds sick. BTW i got the 9" intake and rustys exhaust with the flowmaster 50 series. My bro (who used to own my jeep) and I definetly noticed a difference in power.

[5spd_xj]

alright cool. i'll be trying my luck friday afternoon...any other suggestions from anyone?

[scorpio_vette]

guess i haven't looked at my XJ exhaust in a while, so i might have slightly misinformed you.

i was thinking about alot of the cars i do exhaust on at work. i generally just replace the exhaust from the nearest flange on back, which in most cases is a complete exhaust.

but you're right, the XJ (and the back half of my TJ) exhaust has a couple joints in the back with clamps. so yeah, you could just cut off the clamps and replace them. personally i like to get the exhaust clamps from napa. they have a wide (3" or so) exhaust pipe clamp, which helps seal off better and prevent exhaust leaks.

[8Mud]

When those clamps are tightened up they actually make a groove in both pipes. Getting the pipes back apart again, at the cat can be a pain. Many people use a BFH and forget the exhaust and the exhaust manifold are actually connected and stressing the exhaust manifold isn't smart.
Use a torch to heat the groove, where the exhaust pipe goes over the cat stub outlet. Gently tap the two apart, reapplying heat as necessary.
You can also try cutting the single layer of exhaust pipe with an angle grinder, without cutting the Cat outlet stub. You got to be good. Cutting the pipe diagonally, in kind of a cork screw works best. After the exhaust pipe layer is cut through, you can roll it like a sardine can lid.
Line up the exhaust for clearance before you tighten the clamps. The whole works can hang a little low, if you don't align it some before tightening. No reason you can't double clamp if you think it is necessary other than the trouble taking it apart again. You can actually take a finger full of muffler puddy and clamp it between the two pipes. Pretty much leak proof and not really that much harder to disassemble again.
Before you start, take a look at your hangers. They often need to be replaced.
Welding the pipes together isn't really necessary most times. Unless a connection is really being troublesome or there is a really long run between hangers with a joint in the middle. But for offroad vehicles, three spot welds, really helps keep the pipe joint from flexing and possibly relaxing and leaking. The spot welds can be ground off pretty quick, to disassemble.
When using a torch around the exhaust, a couple of things to remember. Undrcoating burns, makes a hot fire and drips flaming stuff. I keep an old window pump sprayer full of water handy. Also there is padding and carpeting on the other side of the floor boards. if the underbody is coated in oil, keep a serious fire extiguishe rhandy or wash it off before starting. Even an angle grinder can ignite it.
You almost have to jack the rear up pretty high and put jack stands under the frame and let the rear axle hang to get the exhaust out, without way more work than necessary.
Point the bolts for the clamps to the side or up. The excess bolt sticking out hangs on things when off roading and can punch holes in your skull during inspections. A coat of copper grease on the threads, reduces corrosion and helps if the clamps relax some and have to be resnugged. Stainless clamps aren't that expensive (usually double the cost of galvenized) and worth the money. And can be reused almost indefinately. Whatever clamps you get specify heavy duty, most shops have both regular and heavy duty, but usually give you the cheap stuff unless you ask.

[bacelaw]

I'm thinking about doing mine myself as well - i like your method of cutting them apart without damaging the other pipe - is it possible to use metal cutting snips rather than a grinder to make sure you only cut one layer of pipe?

also - the hangers, do they get welded to the floor? are they available at any auto parts store?

[scorpio_vette]

all you need is the rubber bushings for the hanger. there is a small metal rod attached to the jeep, and another one attached to the exhaust. and there is like a figure "8" rubber bushing that connects the 2 metal rods. you should be able to get those at almost any parts store. i usually get them from carquest or napa.

[bacelaw]

what about the flange that goes from the manifold to the downpipe - can i soak that thing with PB blaster for a couple days?

or will the pb ignite and cause a fire?

also - i cant find a source for the downpipe....ebay has cat, muffler, tailpipe for real cheap for the xj's...is it difficult to bend pipe to make it fit?

[scorpio_vette]

that's why i originally mentioned the torch. if you heat up the nuts/flange around the bolt until they glow, they'll come right off.

as for the exhaust parts, i usually stick to more "known" shops such as carquest, napa or dealer.

yes pb blaster will help alot. it'll probably smoke alot, but i've never seen it actually "flame up". and even if it does, it'll be small enough for a normal fire extinquisher.

[bacelaw]

i dont have a torch....and im always leary of using fire underneath my oily jeep.

what about the downpipe - who sells it?

can i bend my own pipe?

[scorpio_vette]

i really wouldn't worry to much about it. keep a fire extinquisher handy, and try to use a little common sense. we use torches around all kinda cars every day, and have yet to start one on fire. sometimes a tiny little bit of grease will get a little flicker of fire, but it's so little you can blow it out yourself.


just make sure you point the flame at the nut, and not the floor. in most cases there is enough room to where you can safely place the flame on the hardware that you are trying to remove without melting/burning anything else.

as for the downpipe, you should be able to find that at a local auto parts store. try a napa, carquest or advanced auto.

[BSH]

I just did my cat-back last weekend. Actually, I got a recall notice on the exhaust/catalytic converter, and they were going to replace my cat, but insisted I get the muffler/tailpipe done first. The stealership wanted $450 for the job!

Anyway, I broke the bolts off of the rear tailpipe hanger clamp, and cut off the clamp behind the muffler with my new grinder. My exhaust system was really old and in poor shape; I couldn't get the muffler apart from the cat for love or money. I ground it off, right through the pipe, right next to the muffler. In my case, they were going to give me a new cat anyway, so I didn't care about it.

Except for the trouble getting the muffler apart from the cat, it was fine. Getting those apart took most of the day.

[bacelaw]

how difficult was it to separate the cat from the downpipe? can u just cut out the cat/muffler/tailpipe and then just replace everything with new hangers?

[Harlee&Tahoe]

I had to cut the pressed in bolts off of the flange and replace with regular hardened bolts. Cat/head tube

[8Mud]

what about the flange that goes from the manifold to the downpipe - can i soak that thing with PB blaster for a couple days?

or will the pb ignite and cause a fire?

also - i cant find a source for the downpipe....ebay has cat, muffler, tailpipe for real cheap for the xj's...is it difficult to bend pipe to make it fit?

You about have to soak the bolts at the manifold to down pipe flange. You also have to be carefull, I most always clean the threads up with a wire brush, before attempting it. Often when you have trouble getting the nuts off they are jammed up with rust and such that gets forced in the threads and piles up. Getting the threasd as clean a spossible, is a pain, but snapping off the bolts can be worse. When taking thwe nuts off, heat from friction is your enemy, if they come off sitff, they can build up lot of heat and something may snap.
I'd have to look to make sure, but I'm pretty sure Crown has the downpipe. The downpipe usually lasts forever and rarley corrodes to the point it has to be repalced. Often looks nasty but has sufficient wall thickness. The exhaust system usually rusts out quicker, the farther away from the motor it is.
Finding a downpipe that fits can be a pain, I've noticed them (the bends) often being near to the original, but often not near enough. Suckers often have a poor fit and contact the tranny cross brace or front driveshaft.

[8Mud]

i dont have a torch....and im always leary of using fire underneath my oily jeep.

what about the downpipe - who sells it?

can i bend my own pipe?

Torch is really the easiest was to do it, though I wouldn't try it at the manifold to donwpipe connection.
I keep a water soaked rag handy, a window cleaner pump sprayer and a fire extiguisher handy. I've never had to use the fire extinguisher, but I feel it is absolutly necessary to have one on standby. One of those "why not" type of things. Or more likely, one of those as long as you have it handy you'll likely never need it, but the first time you don't have it handy things turn to chit quick. I once watched a guy ignite his oil soaked coveralls.
Being carefull which direction the flame is pointed, is necessary, you can also use a piece of sheet steel as protection (a heat shield). You don't have to fear a flame, but you do have to keep your brain in gear at all times.
I've ignited undercoating a whole bunch of times. Stuff burns hot, drips flames and doesn't blow out. Any fluid but coolant (or possibly brake fluid) and you have to anticipate it being a fire hazzard.
I once watched a guy put his XJ up on a lift, take his muffler off (with a torch) and replace it, lower the XJ and then notice the whole inside was full of so much smoke you couldn't see in the windshield. One of those things you don't forget and would feel really really dumb about, if you didn't learn from his mistake and made it again yourself. I've also found learning from somebody elses mistakes, is the least painfull way of learning. I bet it really stunk in there for years.
The rear hanger by the gas tank is often the one that rusts through. Pretty much an OEM part, but I have fabbed my own, using pieces form a universal hanger kit and some of the hardware from the original. It may be avialable at a parts store in the US. Back by the tank is a common place for the exhaust to bang.

[Axle]

I just did a complete downpipe to tailpipe on an '89. Universal cat and muffler, a few feet of tailpipe, new clamps, and made my own flange for the cat (saves money from buying the flange kit or OEM style replacement).

The downpipe flange hardware came off easily, my guess is because they cycle through hot/cold every time the jeep is ran. I did use anti-sieze on everything during re-assembly, just in case I need to pull anything apart in the future.

I never figure on re-using clamps since either I cut them off or I break the threaded part off while trying to remove them. Sawzalls are nice for exhaust work too, fewer sparks than a grinder.

As far as the cat to downpipe goes, on mine both sides of the flanges were weak, plus I had trouble with the studs that hold the flanges to the bracket that goes to the vehicle. I pounded the studs out and replaces them with bolts. I was hoping to reuse the downpipe and the first 6" past the flange (so as not to have to undo all of these) but they crumpled as I started to work on them. The downpipe was reasonable from Carquest, like 38 dollars.

[bacelaw]

axle - how much did the whole thing cost?

i'm planning on the exact same thing.

[bacelaw]

oh, and what did you do about the hangers? a couple of mine are broken.

[Axle]

cat=50 (+30 if bought to fit w/ 4 hole flange)
downtube=40
muffler=20
10' pipe=25
clamps=10 (5 at 2$)
hangers=14 (2 a 7$)

I used a couple of univeral hanger to replace the old ones. I do not have the tailpipe bent over the axle yet, just a downspout out of the muffler right in front of the rear differential. I hope to finish it in my spare time.

Parts were about 160$. A local shop wanted about 300 to do all of this. The kids and I did most of it in one afternoon. I have a pretty good collection of metalworking tools so for me it is mostly figuring out where to buy stuff from and when to put it on. In retrospect I would have paid the extra 30 for the OEM style cat with the flange or the cat adapter kit. It was neat to be able to DIY the flange but that was the largest time drain in the project.

I replaced a 6" straight pipe feeding a burnt-out glass pack that dumped out midship under the jeep. I am liking the stealth-jeep sound, as are my neighbors...

[RandyD71]

You ususally shouldn't have to replace the front pipe as they don't have nearly as many problems becaus eof the heat they endure being that close to the engine. Your factory pipe is stainless and should last quite a while. If you need the rubber hanger at the back of the muffler it is Walker/Napa part number 35750 and the one at the tailpipe is walker/napa 35819. You should be able to purchase the pair for under $30.

[5spd_xj]

WOW. i had no idea it would sound so damn good. that exhaust is freakin b e a u tiful sounding!! and to think, it cost less than 180 shipped to my door! i'm lovin it. thanks for the suggestions guys, it actually was much easier than i anticipated. thanks again for the help.

it sounds so nice i just might have to upload some sound clips somewhere to show it off, haha. i'd suggest this kit to anyone, btw... really good deal i think.