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Unread 03-01-2012, 10:27 AM   #1
Uniblurb
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Leaks when installing new exhaust systems

I've installed plenty of exhaust systems but lately the pipe sizes/tolerances are so bad I end up with leaks on the connections.

This happened with a new muffler and exhaust/tail pipe on my 96 ZJ. Also on my son's 96 XJ where I just installed a new cat, muffler and exhaust/tail pipe.

I install the muffler clamps right next to the edge of the outside pipe. But when tightening down it causes the pipe to pinch out on the sides where the bottom of the clamp meets the top. Then sometimes I'll install another muffler clamp right behind the 1st one, turned the opposite direction, but this doesn't fix the leaks.

Believe they used to make muffler clamps where the bottom section was taller on the outside and didn't have so many leaks. But they also used to make tight fitting pipes.

Just curious if I'm doing something wrong and maybe I shouldn't be putting the muffler clamps so close to the pipe ends?

The leaks were so bad on my son's new exhaust, particularly where the front pipe on the cat meets the exhaust pipe coming down from the header, I ended up trying to braze the leaks shut.

Just wondered if others are having the same problems and maybe offer some suggestions if I'm doing something wrong? Thanks.

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Unread 03-01-2012, 01:19 PM   #2
Smokey1r
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Did your re expand the inner pipe (end of the Y pipe) after removing the old clamp and cat connecting to it?. if you look carefully the clamp creases the pipe essentially collapsing it a little in the clamp location and shrinking it in the surrounding areas slightly, if you just slip a new pipe over it and a clamp the mating surfaces will be severely gaped and have a high potential for leakage. When i replaced the exhaust system on the jeep i drive from the cat back to the muffler i used an oxyacetylene torch to cherry the pipe then tapped inside diameter at the opening of the Y pipe till i pushed out the compression damage. Any rough spots i ground or sanded till the pipe was clean, close to straight as possible and round. when i slid the new cat on it was a perfect fit and the clamp did its job with zero leaks.

The Tailpipe was too short as it had been cut 2 previous times to free it from the muffler and i just got a short extension piece and welded it on making it the proper length again so clamping on that end was mint also.

Hope this suggestion helps you out?.
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Unread 03-01-2012, 04:38 PM   #3
jr4x4
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i did the same thing. replaced from cat back & added 2 -3 clams & no go. i just went & had the whole thing welded.
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Unread 03-01-2012, 05:16 PM   #4
Foundrydude
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When I was younger we'd slather gold RTV on clamped joints before putting them together, but it only works from the mufflers back or it burns out. And you really have to clamp the heck out of em cause the RTV will prevent them from rusting together, so if there's any fit or hanger issues they slide apart.

Otherwise I would say harbor freight has a wire welder on sale for $90, meaning for $150 out the door you can get a welder, auto darkening helmet, and a pair of welders gloves. Anybody doing their own exhaust really needs a welder. It's an investment you won't regret, unless you love welding so much you regret buying a $90 welder rather than a $450 welder.

good luck
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Unread 03-01-2012, 06:55 PM   #5
Uniblurb
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Quote:
Originally Posted by Smokey1r View Post
Did your re expand the inner pipe (end of the Y pipe) after removing the old clamp and cat connecting to it?. if you look carefully the clamp creases the pipe essentially collapsing it a little in the clamp location and shrinking it in the surrounding areas slightly, if you just slip a new pipe over it and a clamp the mating surfaces will be severely gaped and have a high potential for leakage. When i replaced the exhaust system on the jeep i drive from the cat back to the muffler i used an oxyacetylene torch to cherry the pipe then tapped inside diameter at the opening of the Y pipe till i pushed out the compression damage. Any rough spots i ground or sanded till the pipe was clean, close to straight as possible and round. when i slid the new cat on it was a perfect fit and the clamp did its job with zero leaks.

The Tailpipe was too short as it had been cut 2 previous times to free it from the muffler and i just got a short extension piece and welded it on making it the proper length again so clamping on that end was mint also.

Hope this suggestion helps you out?.
Thanks and sounds like the right way to do it. But unfortunately I don't have a torch or a welder. When I said, "I ended up trying to braze the leaks shut", I was using a Mickey Mouse bernzomatic torch. Used to use a torch/stick welder all the time at work and really miss them.

I know exactly what you mean about the end of the exhaust pipe having a crimp in it where the old muffler clamp was. I even measured exactly where this was and tried to put a muffler clamp on the exact same place. No luck and the 2nd clamp was even closer to the end which didn't stop the leak either. Doggone cat pipe was just too big where it fit over the exhaust pipe. And so were the other two pipe connections where it was all brand new pipe.
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Unread 03-01-2012, 07:11 PM   #6
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Quote:
Originally Posted by Foundrydude View Post
When I was younger we'd slather gold RTV on clamped joints before putting them together, but it only works from the mufflers back or it burns out. And you really have to clamp the heck out of em cause the RTV will prevent them from rusting together, so if there's any fit or hanger issues they slide apart.

Otherwise I would say harbor freight has a wire welder on sale for $90, meaning for $150 out the door you can get a welder, auto darkening helmet, and a pair of welders gloves. Anybody doing their own exhaust really needs a welder. It's an investment you won't regret, unless you love welding so much you regret buying a $90 welder rather than a $450 welder.

good luck
Yeah, I used to use muffler putty and it would brake down too. I still have some and was half-temped to put some on the exhaust pipe the front pipe of the cat goes over. Thought no way do I want to start clogging up the screens on a new cat so threw that idea out the window.

You're right I need a welder and used to use a stick one all the time. Could you please supply a link to one you saw at Harbor Freight since I couldn't find it? I'm also not familiar with wire feed welders.

I've been looking at welders lately and have a feeling if I get one which will only weld up to 3/16" steel sure enough I'll run into some thicker steel I need to weld. Problems with having 4 aging/rusted Jeeps to repair/maintain.

Thanks!
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Unread 03-01-2012, 08:53 PM   #7
Foundrydude
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Harbor freight number 68887 and 98871, normally $149. They just sent me a flyer with a coupon for $89, and usually the fliers are available when you walk in the door.

90 amps will do any repair on a unibody vehicle, if you want true capability like rollcage or trailer building, then 130-140 amps is the minimum buy-in. Price will jump to +$400.

The harbor freight wire is terrible and has an uneven burn rate which makes it hard to weld. Lincoln or Miller brand wire will solve that problem. The HF wire is probably fine for exhaust but anything more you'd be wise to throw it away and buy decent wire.

The ground clamp is also a piece of garbage. If you buy the HF welder start keeping one eye open for a better ground clamp with stronger springs, lots of jumper cables have better clamps than this welder. A decent ground clamp is not much money from a weld store, and having a better ground will make the welder seem more powerful.

The harbor freight welder is honestly not the greatest, but it's plenty good for exhaust work and light backyard repair. And it's probably gonna be worth $50-75 used if you ever decide to upgrade to a proper lincoln/miller/hobart welder.

good luck
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Unread 03-01-2012, 09:31 PM   #8
ahoyt653
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I had the same problem, I corrected it either band clamps. They are a little more expensive, but they did the job
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Unread 03-02-2012, 09:37 AM   #9
Uniblurb
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Quote:
Originally Posted by Foundrydude View Post
Harbor freight number 68887 and 98871, normally $149. They just sent me a flyer with a coupon for $89, and usually the fliers are available when you walk in the door.

90 amps will do any repair on a unibody vehicle, if you want true capability like rollcage or trailer building, then 130-140 amps is the minimum buy-in. Price will jump to +$400.

The harbor freight wire is terrible and has an uneven burn rate which makes it hard to weld. Lincoln or Miller brand wire will solve that problem. The HF wire is probably fine for exhaust but anything more you'd be wise to throw it away and buy decent wire.

The ground clamp is also a piece of garbage. If you buy the HF welder start keeping one eye open for a better ground clamp with stronger springs, lots of jumper cables have better clamps than this welder. A decent ground clamp is not much money from a weld store, and having a better ground will make the welder seem more powerful.

The harbor freight welder is honestly not the greatest, but it's plenty good for exhaust work and light backyard repair. And it's probably gonna be worth $50-75 used if you ever decide to upgrade to a proper lincoln/miller/hobart welder.

good luck
Thanks for all the info. There must be more Harbor Freight stores in your area and only found a couple here which are about 30 miles away. They have the price of the Chicago Electric 98871 marked down from $150 to $110.

If I needed a better ground clamp I have one of those portable battery jumpers which is dead. It's an older model and the clamps are actually better than the HD ones on my jumper cables where I could cut one off to use.

Guess I need to figure out if a 110-120V welder will service my purposes. It would work great for exhausts and repairing/replacing the rocker panels on my 93 XJ which are rusted away. But I'm scared to even use my trailer hitch on my ZJ since it's about rusted off the frame. Also have a new steering stabilizer to replace but the bracket the bolt goes through is about rusted off the axle/bracket. Know it would probably take a 130-140 amp welder to do repairs like this but maybe not?

Also need to look at the convenience of a 110/120V welder vs 220V. My 100 amp breaker box is already overloaded and power company almost shut me down if didn't upgrade to 200 amp. But I do have a 220V receptacle in my basement I wired into the current box. Outside wall where I work on my Jeeps is only 8' away where I could easily run wire to an outside 220V receptacle.

Almost thought about looking for a used 130-140 amp welder online but afraid it may be worn out or abused.

BTW, don't ever put 100 lbs of rock salt on you steep 800' gravel drive covered with ice. Then use your XJ to tear up the slush, when starting to melt before it freezes again, w/o washing the salt off. It ate the metal big time and sure wasn't good for my ZJ & TJ either.
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Unread 03-02-2012, 10:18 AM   #10
zjosh93
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Most auto parts stores rent tailpipe expanders that fit into the pipe and expand as you tighten the center bolt. The ones you can rent are not really strong enough to expand the pipe without using an impact but they will push out the old clamp divot and make the pipe round enough for new clamps.

I got a 135 amp MIG from Northern Tool last June for maybe $320 on sale and with a coupon. Bought a tank of mixed gas and an auto darkening helmet and haven't looked back. I always liked welding but this set up is light years ahead of the stick welder and gas rigs I used before. Get shielding gas! Gas is way better than flux cored stuff. Be aware that the cheap Harbor Freight machines have only one or two amp settings so they are harder to use.
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Unread 03-05-2012, 09:37 AM   #11
Uniblurb
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Thanks for the tip on local auto parts stores renting out tailpipe expander kits. Just called the local Advance and the manager checked on the condition of it and if it had a 2 1/2" expander. Good to go and he said I pay $89.99 for it but when I bring it back they give a full refund. So more like at loaner at no charge which is nice.

Believe I may have made a mistake by not replacing my cat when I installed a new muffler and tailpipe on my ZJ. The 4.0L seems underpowered compared to our other I6 Jeeps and not sure if it could be the cat? It was installed by Midas Muffler (big mistake) about 6 years ago. The lifetime muffler rusted through in less than 2 years which makes me wonder about the quality of the cat? Also when I cut/chiseled the muffler pipe off it broke the weld on the rear cat pipe. I brazed the pipe back on so it doesn't leak but it's out about 1/2" more than it was.

Is there anyway to check the cat performance, or see if it's partially clogged, with a scanner (just bought an Actron 9575)? Know I should have tried looking through the cat when I had the muffler off but didn't. Really don't want to take the exhaust system back apart unless I'm going to replace the cat.

Still looking at different types/models/prices of welders and know I need one.

Thanks for any input.
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