Has anyone ever tried welding truck exhaust manifolds? I know you are not supposed to MIG cast iron but I have done it before with decent results, at least short term. I know there are lots of different varieties of cast iron so wondering if these manifolds are particularly bad or good for welding.

 

Evidently the truck manifolds are not your father's cast iron. I got inspired by what some of the turbo guys were doing welding on V-bands and tried removing the EGR boss and welding in a patch. I pre-heated in an over for an hour or so, did my welding and then stuck the manifold back in the oven and turned off the heat and let it cool slowly. No problems after 8 months and more than 7,000 miles.

 

thats probably the best way to do it so it does not crack. once the cast iron cracks its hard to fill in the crack it keeps getting bigger

 

If you go to the welding shop they have welding rod for cast iron. They aren't cheap and you don't get but a few rods. I have welded a few import eh cause manifolds that cracked and they haven't had an issue in years.

 

Try a search... This topic has been discussed multiple times...

 

Ive done it. Little prep done and welded great. I just heated them a little and let cool in sand. Used Flux Core wire with gas. Made a pretty weld too

 

Cast iron will crack eventually, even when using the special welding rod aka "nyrod" it's nickel rod basically. I've welded a lot of cast stuff, cast iron, cast aluminum, cast steel... It will all crack over time, may be years, but it will.

 

I welded my manifolds with my MIG and have had no problems. I cut the flanges off and bevelled the edges then welded vbands to them. Then when I converted to turbos I welded a short piece of pipe to another set for the turbo flanges.

 

We use a rod called Crown 260. Works fine.

 

People should be banned for making post like these. SEARCH and literally hundreds of threads would have shown up.

 

Probably find they are cast steel not cast iron.

I have welded a number of G8/commodore manifolds here in oz with mild steel mig wire and never had a cracking issue, these are also cast steel. These manifolds look the same as the latest Comaro manifolds.

The truck manifolds are possibly the same cast steel, there is a simple way of checking by getting a known piece of cast iron and grind on it with your grinder and take note of the colour of the sparks, then grind on your truck manifold and if its cast steel it will have different colour sparks compared to the cast iron.

 

mig welded mine... no issues.

 

I need to do this also. What wire and gas are you guys using with your mig welder? I have enough truck manifolds to practice on.