Repair or Replace? (Exhaust pipe crack - [Photo]) - PeachParts Mercedes-Benz Forum

EricSilver · #1 08-19-2009, 10:58 AM

I lost an exhaust hangar which caused my exhaust pipe to flex over and over, and a crack occurred just ahead of the center muffler/resonator.

It is cracked at the weld but not rusted through, so I would think it can be welded.

Black residue on bottom/front of resonator is blown-back oil from a timing cover leak.

EricSilver · #2 08-19-2009, 11:01 AM

Photo Did not Attach in First message. Here it is.

865sp300e · #3 08-19-2009, 12:18 PM

Mine developed a similar crack and the local indy muffler shop welded it for $20.

EricSilver · #4 08-19-2009, 12:48 PM

Great -- thanks.

I am finding the muffler shops are saying "replace," whereas indy repair shops and independent welders are saying they can probably re-weld it.

babymog · #5 08-19-2009, 09:33 PM

All depends on how thick the remaining metal is, ... usually it'll burn through quickly if it's rusted thin and thus can't be welded.

emerydc8 · #6 08-19-2009, 09:39 PM

I have used PC-7 to patch the same spot on my exhaust. It works very well.

EricSilver · #7 08-19-2009, 09:55 PM

Quote:

Originally Posted by babymog

All depends on how thick the remaining metal is, ... usually it'll burn through quickly if it's rusted thin and thus can't be welded.

Metal thinness was the concern of an indy boiler welder who I asked about it, and may be able to help. But tomorrow morning I will be taking it to a local Chevron station that does welding, and who believe they can fix it. If they can, I will let them.

mpolli · #8 08-19-2009, 10:06 PM

Welding is a weird science. It could depend on the alloy(s) there.

You might post that photo on http://weldingweb.com and see what the alchemists there say. You could post under General Welding Questions or Mechanic's Park.

EricSilver · #9 08-19-2009, 10:14 PM

Quote:

Originally Posted by emerydc8

I have used PC-7 to patch the same spot on my exhaust. It works very well.

I had not heard of that -- but just Googled it.

If I am unable to get it welded I will use that or Permatex Metal repair epoxy, and then secure a thin pipe clamp over it to keep it from blowing out.

The muffler is only a few years old, is a genuine MB part, and I cannot come to terms with throwing away something that is perfectly good.

I also saw that both tailpipe hangars are broken, as if cut. Considering the thickness of the rubber, I am having a hard time accepting that the weight of the muffler could have broken both of them -- or is that common?

EricSilver · #10 08-19-2009, 10:30 PM

Quote:

Originally Posted by mpolli

Welding is a weird science. It could depend on the alloy(s) there.

You might post that photo on http://weldingweb.com and see what the alchemists there say. You could post under General Welding Questions or Mechanic's Park.

Thanks!

emerydc8 · #11 08-19-2009, 10:44 PM

The PC-7 works without any clamps. It is like silly putty when you mix it and you can work it into the cracked area enough so it grips really well. Let it dry overnight if you end up using it. It will probably be stronger where you repaired it than the rest of your exhaust.

EricSilver · #12 08-19-2009, 10:58 PM

Quote:

Originally Posted by emerydc8

The PC-7 works without any clamps. It is like silly putty when you mix it and you can work it into the cracked area enough so it grips really well. Let it dry overnight if you end up using it. It will probably be stronger where you repaired it than the rest of your exhaust.

OK. Is is heat resistant? And where do you buy it?

I taped thin strips of Gorilla Tape Around the periphery of my broken hangers, and am about to reinstall them. That should at least relieve the stress on the crack tonight, and during my drive to the dealer to get new ones.

emerydc8 · #13 08-20-2009, 01:23 AM

It seems to be heat resistant. About 4 months ago, I drove over a metal cover at a car wash that was not properly secured. The cover came up and hit my muffler, cracking both exhaust pipes where they go into the muffler. I have used it successfully in the past on my 400E exhaust as well.

You can buy it at Ace Hardware for about $15.00. You have to mix the two compounds with a putty knife. After the repair, you will smell the epoxy for a few days after you park the car when it's hot, but the smell eventually goes away after a week or two. I can't believe how strong the PC-7 is.

EricSilver · #14 08-20-2009, 06:53 AM

Quote:

Originally Posted by emerydc8

It seems to be heat resistant. About 4 months ago, I drove over a metal cover at a car wash that was not properly secured. The cover came up and hit my muffler, cracking both exhaust pipes where they go into the muffler. I have used it successfully in the past on my 400E exhaust as well.

You can buy it at Ace Hardware for about $15.00. You have to mix the two compounds with a putty knife. After the repair, you will smell the epoxy for a few days after you park the car when it's hot, but the smell eventually goes away after a week or two. I can't believe how strong the PC-7 is.

I've been reading the reviews and everyone seems to love it. My only worry is that it is temperature rated to 200 degrees F, but if you have been using it successfully on your car, with a larger and presumably hotter exhaust than mine, I'll try it.

Also, I am seeing PC Fahrenheit, specifically designed for high temps, however, that is a hand-moldable putty which I expect may not be as strong as the PC-7(?)

865sp300e · #15 08-20-2009, 08:52 AM

I have used PC-7 with good results in the past. Unfortunately in my state, Pennsylvania, they visually inspect the exhaust system and failed my car due to the patch.

I had a sleeve welded over the break which was acceptable for the state inspection.