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Discussion Starter #1 (Edited)
I've got myself into a little predicament here, and need some sound advice.

I usually drive my truck out about 150 miles to the GMC dealer in Chinook for repairs. Our local shop will rape ya every chance they get.

Two weeks ago I got the rear end hung-up and ripped the exhaust pipe clean out of the passenger's side muffler. It's just "hanging there".

I don't usually go for hokey repairs, but have been inclined to a little ******* ingenuity in a pinch.

Problem is, I don't know how to temp repair this, and have heard mixed opinions.
I don't want to take her out of the garage at the moment, because we've got freezing weather. I don't want to suck some -10F air up in the manifold and crack the block.

Does JB weld work for this? Will it hold? Maybe in combination with muffler tape?

It's a 3/4 ton GMC, crate big-block 454 7.3, dual-exhaust with a gas-eater 4 barrel Edelbrock carb and aftermarket intake manifold.



Thanks in advance!

~Frau
 

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Student/Teacher
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Without seeing it its hard to say but what I have done in the past is to use a smaller diameter pipe jammed in the muffler and exhaust pipe taped and clamped. I hate going to garages I do not know.
 

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*** Forgives, I don't
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J-B weld would work but lately for minor repairs I have been using Plumbers Putty. Alighn the pipe with the muffler and spread it evenly around the crack. Let it sit about 2 hours and add another layer (overlapping the other). Make sure the pipe is secured to take the weight (stress) off the putty. Once it dries (cures) completly it should be OK, until you can find someone to weld a new piece in place.
 

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The Punisher
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I'm taking it that you broke it off at the muffler, and not the manifold? In cases such as this, that is when I break out the Sawzall.:D:
 
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RockOut w/ your GlockOut
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If you only knocked the muffler off and the exhaust pipe is still connected to the manifold and the manifold is still connected to the head, it is no big deal. You can drive aroud w/ straight pipes as long as the heat is not melting parts under the vehicle. You will have min. loss of pressure and run louder. The only way you could possibly crack the head from cold air is if you had a leak between the exhaust manifold and the head.

There should be a clamp that probably fell off, it is probably just seperated. Get a clamp and put it back together.
 

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Discussion Starter #8
I'm taking it that you broke it off at the muffler, and not the manifold? In cases such as this, that is when I break out the Sawzall.:D:
Take the muffler out and just run the straight pipe?

I apologize for the dumb-a** questions, I've never done any bottom-end or tranny repairs.

Yes, the muffler is still there, just the pipe is no longer connected to it.

Thanks for the comments about the cold air. This is where I was most doubtful, and why I sought some sound advice. i thought with the manifold in-place you really couldn't draw backward into the block, but I didn't know if this was true. Just don't want my ignorance of some seemingly simple repair to do that kind of damage.

As an aside, will this make for constant carb adjustments? She seems to be rather sluggish since this happened? Maybe it's just coincidence with the weather?

Thanks.
 

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if your exhaust got ripped off BEFORE the muffler maybe i doubt it has a cat, but if it did and the exhaust was disconnected before the cat, that could lean out your fuel air ratio. but behind the muffler i doubt it.
 

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Discussion Starter #10
k, I'm gonna crawl up in there and take a really good look. I thought, upon first inspection, that it was just the pipe out-going from the muffler. But if there is a possibility the intake changes could be significant, then I need to see what's really going on there.

Dropped by the local shop for a weld, and they quoted me 150 give or take, which I thought was ridiculous. Cheaper to rent a welder at this point, and fix all kinds of things around the house heh. :D:
 

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Finding a friend with a welder is probably your best bet. As long as the pipe is not dragging on the ground, you can drive it.
 

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Discussion Starter #15
Thanks all for your replies.

All the welds look fine, and all clamps are tight before the muffler:



This little bracket here is what's loose - I can twist the pipe freely at this point:



But.. I did discover all kinds of carbon on the backside muffler bracket - everything there so corroded and blackened I don't even know if it'll weld.
Seems I didn't actually rip it off, but blew it off somewhere - you'd think I'd have heard that... :eek::

Now that I'm comfortable in knowing I won't damage anything in so doing, I'll take her to the shop.

Thanks again, much appreciated!
 

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If you have an auto parts store just get a new U bolt and nuts or the whole bracket with u bolt and replace the existing one. You will need penetrating oil or a sawsall (and since it looks to be next to the gas tank don't saw into it:D:) to remove the old. Just make sure you don't have any leaks that can put carbon monoxide into the cab. Not a nice way to die.
 

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grease monkey
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I believe what you are referring to, is a rush of cold air entering the head, and warping or damaging your valves. In extremely cold weather, this is a real and serious concern, and you are right to be asking ?'s. But here's the thing : If you have an exhaust leak way back towards the rear of the truck, everything should be fine. It's when you actually have a leaky exhaust manifold (very close to valves) that you have a problem. The valves get extremely hot during operation, and once you get where you are going, you turn the truck off. That's when the cold air rushes in, and wreaks havoc on your valve train. Since your leak is way back by the muffler, you have...I'm guessing about 8 feet of nice warm pipe hooked to your heads. In other words, drive it anyway. It will be fine. I would recommend turning up the radio a little though. Plus, if your muffler is old and your pipes breaking, it's time for a new one anyways. I like flowmaster. But seriously, you could drive around for years and probably never have to worry about it. As far as the "sluggishness" is concerned, that seems a bit contrary to logic. no muffler = better flow, better flow = h.p. I think what has happened, is removing the resistance in the exhaust system has changed you power curve ever so slightly, more to the top end. You may feel as though you are lacking a bit of power right from the stoplight, but in the end, you should actually have 3-5 more horses depending on A LOT of different specifics. :)
 
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