I have a leaking coupling between 2 exhaust manifolds on a Cummins big truck engine. Could it be brazed up to stop the leak. I don't really have time to shut down and replace them right now. It is made of cast iron.
Way back when I had my own machine shop I would braze cast iron because it was the only way to save the piece. But today's technology has advanced so much that there may be other stick welding rods capable of doing it quicker than torching. Call a few shops handling Caterpillar like stuff.
You can probably weld it with a nickel rod. Gouge out a vee shaped area around the crack,and weld it while its still hot. Run the truck after welding and put a good load on it to keep the exhaust temperature well up. This should get you through to the next chance for a shutdown to replace it.
Brazing us not likely to stand up to the high temperatures especially if there is a turbocharger downstream. Cast iron welding rod (Ni-Rod) would be the way to go. Preheat before welding by running up the engine temp and then running the engine afterward for post heat. If it is going to crack it will when the assembly cools down. Peening the weld with a small hammer will help to stretch the weld as it cools from a red heat. There are a lot of computerised controls and sensors on modern truck diesels. Keep the ground immediately next to where you are welding. Check your manual for any cautions about welding on the truck. Randy
"Clif Holland" wrote in message news:Cs6jf.3134$to5.2902@trnddc04... I have a leaking coupling between 2 exhaust manifolds on a Cummins big truck engine. Could it be brazed up to stop the leak. I don't really have time to shut down and replace them right now. It is made of cast iron.
Hi Clif,
Not only am I interested in the repair technique but I am especially so because I also have an old Freightliner with a Cummins 855.
Could you explain what the coupling is? Is it part of the manifolds? Or does it go into the engine head?
Vernon
Those two pieces will move relative to eachother by a good ways when up to temp. You'll either have to remove them and reseal them properly, or find something that can work as a high temp patch and remain flexible. I don't know of anything that would work. Braze will melt out, something higher temp will crack right away, and a solid weld will likely crack the manifold again somewhere else.
Preheat with a weed burner if possible
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.