Okay so my old truck needs to go in for emmisions testing again. The whole exhaust system is pretty shot and I need to replace it all, but I don’t have the cash right now. So i’m just looking to get it past the test for a few weeks until the cash is a available. However the final piece of tailpipe is not on it right now, having fallen out. I can’t put it back into the coupling very well, because the pipes are so rusted, if I try to tighten the bracket, it may very well just break the pipe. So my thought is to glue it in place. So does anybody know if JB weld can handle exhaust temperatures? or will it start giving off strange substances that will screw up the test? has anybody here used it for an exhaust system?
I once tried to use JB Weld to re-attach the heat shield on my catalytic converter (1997 Mazda B-Series pickup). It didn’t work, but I should explain why in more detail - it might do OK for what you’ve got in mind.
The heat shield hangs beneath (and is welded to) the converter on this vehicle, and the (two) tack welds on one side had come loose. It was still attached, but was flapping around and making disquieting noises. I tried to “re-weld” in the same spots using JB Weld.
They both came loose fairly quickly. I think, though, that it was the thermal stresses caused by expansion of the (I believe dissimilar) metals, rather than the heat itself, that led to the failure. I don’t know this, though.
You might be OK. I don’t think the tailpipe gets quite as hot as the converter itself (which gets really hot), and the geometry you’re dealing with might not cause thermal stresses as severe.
I think it’s worth a try - IMO it stands a good shot at success.
I wound up using water heater strap to re-anchor the heat shield. It’s held on just fine for several years now.
There’s a fiberglass mesh tape product I used once. I can’t recall the name of it, but if you go to a decent auto supply store they ought to know what you mean. It was really easy to use, and held up for a long time.
Use duct, it can hold just about anything together. (I have heard stories of people using duct tape and baling wire to hold together a broken truck axle for short periods of time.)
Ah, here it is! Great stuff, if you ask me.
There is a type of auto exhaust repair putty that should work at least temporarily. It’s a gray paste, available in flat round cans (3/4" high, 5" diam.) and also in plastic squeeze tubes. It is NOT the black sealer product. One brand sold years ago was “Holts Gun Gum” (possibly no longer distributed in the U.S.).
I doubt you’ll be able to get the metal clean enough for JB Weld to adhere.
Repair tape is great when you can wrap around something, e.g. a hole in the middle of a pipe. It would be virtually impossible to get it to conform properly to the intersection of the muffler and tailpipe.
Surely you know duct tape would melt or ignite in short order.
Are you sure the tailpipe must be present for emissions testing? The “tailpipe sniffer” used can just as well be inserted into the muffler if the tailpipe’s gone.
Well the coupler somehow ended up much larger than the pipe that fits into it(probaly an 1/8 inch gap at the top). I can easily fit the pipe in, I just know it will not stay with the driving vibration, and as I said I don’t think I can crank the bracket down without breaking the pipe. I was hoping the fact that a fair amount of the cement will be pushed internal into the gap will help it hold and bond, but with the heat problem I don’t know if it will really seal the gap and hold it in place.
After reading Q.E.D.s link it seems like that may be a damn good answer. since it does have a high temperature epozy component. .I don’t need the fancy ceramic heat-shielding tapes that cost more than I want to spend, but his link seems perfect and temperature safe.The pipe is stuck in the coupling and wraping around would be easy So if I’m missing something let me know, but it sounds like a very good solution.
In Colorado the emisions testing on 25 year old vehicles is done very simply at stations with a hose thrown over the tail pipe and the computer analysizes while the operator walks off and deals with the fancier cars. If there is no extruding tailpipe they will have no idea what what to do and will fail it.
And I thought about duct tape for a second, but knew it wasn’t going to work. 
The pipe is stuck in the coupling and wraping around would be easy. So if I’m missing something let me know, but it sounds like a very good solution.
It may well be that I’m missing something. I envisioned the entire tailpipe loose from the muffler, with just a flat surface (muffler end plate) with a hole in it. That would require sealing at a corner, where the pipe intersects the flat end plate of the muffler.
Now it sounds to me like you’re talking about fitting one pipe into another, in which case the tape may work quite well. The putty I mentioned would also work, but without seeing it I couldn’t say which way might be better.
There is no magic repair, I have tried this stuff before, its a waste of time and money, if your exhaust is gone enough to need temporary fixes to pass inspection, you need a new exhaust. Its very unlikely a competent inspector will pass an exhaust that is falling apart and held together with bailing wire and tape.
If you have sound parts to work with and just a section is bad you can get adapters and couplings and short pieces of pipe at an auto parts store.