I just noticed a complete break in my exhaust manifold. I can fold a piece of paper twice (four sheets) and easily slide it completely through the manifold (see pic below). A couple questions:1) For the last 6 - 8 months, I’ve noticed the exhaust brake doesn’t do much. Could it be the exhaust brake baffle is working, but the pressure is escaping through that crack?2) is this a “must fix right away” item? 3) Any recommendations on where to get a new manifold (i.e. does brand matter)? It’s a 1999 275 hp Cummins ISB in a Freightliner XC chassis. (I'd just hosed off the inside of the engine compartment, thus the wet spots on the manifold)Thanks,

This is what I would do with it..... Many would disagree, but I am archaic and all about saving money.I'd get a welder and have them weld a bead right over that crack. A good arc welder will fill the void and help bind stuff up.No it's not the correct way to do something, but I've done it before 10 years ago, and its still working.

The longer it leaks, the worse the crack. I wouldn't let it go for too long, but I see NO black residue around the crack...no immediate concern. It's hard to see if any components could burn by the gas escaping. Blowing hot gas on the head could warp it. Real cast iron welding takes a skilled hand and it's process. Call some used parts yards or get a quote for a new one...the price might not be too shocking...your MH isn't very old.

Yes cast iron can be welded by a skilled welder that knows the process and uses the correct alloy welding rod.

Unfortunately this is a common Cummins problem. The crack goes all the way around and trying to weld it back together will be a waste of time and money. You could replace that half of the manifold but for around $400 you can buy all new for around $400. Start soaking all of the bolts now with PB blaster or Kroil. You are loosing power to as the turbo is not getting as much air to spin it.

Had to replace mine just went to a cummins dealer and bought the part. Used PB Blaster to soak the bolts and replaced the manifold. I was surprised as the coach was about 16 years old at the time and I still removed the bolts fairly easily. I have been told to watch my cool down and to not shut the motor off until it has cooled at idle for about 5 minitues after a good run.

Cracked Exhaust Manifold | Good Sam Community

15 Replies

Dog_Trainer
Explorer
Jan 13, 2014
Had to replace mine just went to a cummins dealer and bought the part. Used PB Blaster to soak the bolts and replaced the manifold. I was surprised as the coach was about 16 years old at the time and I still removed the bolts fairly easily. I have been told to watch my cool down and to not shut the motor off until it has cooled at idle for about 5 minitues after a good run.
Ivylog
Explorer III
Jan 13, 2014
Unfortunately this is a common Cummins problem. The crack goes all the way around and trying to weld it back together will be a waste of time and money. You could replace that half of the manifold but for around $400 you can buy all new for around $400. Start soaking all of the bolts now with PB blaster or Kroil. You are loosing power to as the turbo is not getting as much air to spin it.
barnaclebill
Explorer
Jan 13, 2014
Yes cast iron can be welded by a skilled welder that knows the process and uses the correct alloy welding rod.
1971duster340
Explorer
Jan 13, 2014
The longer it leaks, the worse the crack. I wouldn't let it go for too long, but I see NO black residue around the crack...no immediate concern. It's hard to see if any components could burn by the gas escaping. Blowing hot gas on the head could warp it. Real cast iron welding takes a skilled hand and it's process. Call some used parts yards or get a quote for a new one...the price might not be too shocking...your MH isn't very old.
crasster
Explorer II
Jan 13, 2014
This is what I would do with it..... Many would disagree, but I am archaic and all about saving money.

I'd get a welder and have them weld a bead right over that crack. A good arc welder will fill the void and help bind stuff up.

No it's not the correct way to do something, but I've done it before 10 years ago, and its still working.

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Cracked Exhaust Manifold

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