Welding exhaust manifolds

[2005F250]

Well I have a question. Exhaust manifolds are cast iron (I think) and sometimes they crack. I know you just can't MIG weld over the crack but there should be a way. What I am thinking is drill a little hole at both ends of the crack so the crack doesn't grow anymore. Then get out the torch and brazing rod and go to work brazing the crack so there is no more leaking. I'm pretty sure you can braze cast iron without running the risk of ruining it anymore. I'm pretty sure this will work but I want to get some input on this. Also to can you use a TIG welder since it is similar to the torches?

[Jeff_Northon]

High temperature adhesives. High Temperature Adhesives and Epoxies, Ceramics, Insulation, Epoxies and Epoxy

[2005F250]

Well the crack I'm looking at is on a cummins right were all of exhaust ports go into the turbo. I'de rather to try and weld it so it won't crack anymore and fall off.

[Rattlebox]

Had good luck TIG with phosper/ bronze filler long ago, beat the heck out of a test peice and the "weld" and surrounding cast broke away from the rest of the casting. Check with Airco or Praxair welding supply store. Clean the unit real good first. mabe even gouge a small vee to get to clean material. Always disconnect the battery if you weld on a vehicle with a onboard computer, but it would be best to remove the manifold. Anyone else use phosper/ bronze with a TIG?

[2005F250]

Originally Posted by Rattlebox

Had good luck TIG with phosper/ bronze filler long ago, beat the heck out of a test peice and the "weld" and surrounding cast broke away from the rest of the casting. Check with Airco or Praxair welding supply store. Clean the unit real good first. mabe even gouge a small vee to get to clean material. Always disconnect the battery if you weld on a vehicle with a onboard computer, but it would be best to remove the manifold. Anyone else use phosper/ bronze with a TIG?

I was just thinking of using the TIG torch to melt both sides together and not using any type of filler metal.

[Rattlebox]

You probably will need a filler, I have never seen cast iron fusion welded. Some folks weld it using a stick welder and a nickle alloy rod. Preheating the base metal helps too. Good luck, let us know what worked for you.

[cstroke69cpy3]

ive used the tig with cast, works alright.. Preheat is important, as is cooling slowly several different things to do.. Can put in oven afterwards and bring down temp slowly, or after welding put in lime or sand to let heat dissipate slowly.. I like welding cast with nickel rod. Surface prep is important grind out in vee and make sure its clean.. Also take piece off the truck, when welding the small bbs could go where you dont want them..
good luck
chris

[720Deere]

The only sure way to weld cast is with a torch and cast rod. The part needs to be preheated to 1200 degrees and that temperature maintained throughout the process. After the repair is made the temp must be lowered over the course of several hours so as not to create stress fractures.

I have a local guy that will amaze you with the repairs he has made to cast iron. Some of them still going strong after 30 years of service.

[StarDriver]

I know this can be a probelm on the Cummins, ( mine hasn't cracked yet.), that is why there are now 3 piece manifolds which flow better also. I'm going to get one when I get the chance.

[cstroke69cpy3]

Originally Posted by 720Deere

The only sure way to weld cast is with a torch and cast rod. The part needs to be preheated to 1200 degrees and that temperature maintained throughout the process. After the repair is made the temp must be lowered over the course of several hours so as not to create stress fractures.

I have a local guy that will amaze you with the repairs he has made to cast iron. Some of them still going strong after 30 years of service.

welding cast with a torch is a great way to weld cast, but not many are capable of doing it.. Its becoming a lost art.. Also its done with a carbonizing flame.. which means it has a little less oxygen, its done to put more carbon into the weld.. If you can find someone who is competent either oxyfuel or stick with nickel rod should be a great fix..