Thread: Welding a cast iron exhast manifol

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Have a crack in a 1999 sunfire exhast manifol. Have some nical rods. 1/8. Should I use DC or AC ? Thanks John.

Go to your local welding supply, they sell rods just for doing cast iron,gouge out a small groove at the crack, then preheat the manifold to i believe 700 degrees, weld the spot then slowly cool the part in sand or oil for like 8 hours, do not throw it in water it will crack again

Is it a ''hard to get'' part? Salvage yard replacement might be easier.... if you can find one.

Originally Posted by hotroddaddy

Go to your local welding supply, they sell rods just for doing cast iron,gouge out a small groove at the crack, then preheat the manifold to i believe 700 degrees, weld the spot then slowly cool the part in sand or oil for like 8 hours, do not throw it in water it will crack again

What he said....not too sure about the temperature, but......ensure that it's very hot, too hot to handle. Ensure your sand or oil is extremely hot too, before you start.
I have used stainless steel rods too on cast parts before now, with great success.

johnboy

well i posted before on welding iron blocks i have welded some blocks but the quaity of the iron has alot to do with how good it welds i like the 700 weld mold rod and run it in AC have welded many decks and blocks it works great it is the best i have used other NIc rods just seam not to work as good you do not have to get it that hot 500 and let cool slow ex manfolds can be tuff they have burnt iron and mill on them this needs to be ground off were you weld i just did a gto Ex with the 700 rod it work great built up some of it where it was crack i U grooved it out and you must peen it as you go and getting it warm helps but on to hot or it will crack of sure you need to find the ends of the crack i go past them just a bit U grooe and weld a cross the ends then weld up the crack i weld no more than 3/4 and peen then grind the end where i stop and start to keep slag out

See if you can find someone with a metal spray torch, those work great for cast iron repairs. It's kind of like brazing, kind of like welding, but something entirely different. You heat with a torch like brazing, but spray an alloy like nickel 99, used for welding. There is no mixing of nickel except of the very surface, so the joint has much better mechanical properties and is more easily ground/machined.

76gmc likes the spray torch. i am not that crazy about them .WHY ??heat and alot of it at this point then you should weld it with iron filler rod. i haved used both .i will sell you my spray torch. i haved tig and sprayed and arc iron you best shot is with the pure nickel nic rod runing in ac or the 755 rod copper-nickel and you do not have to put it in a oven to do it

http://www.muggyweld.com/castiron.html

see what he say about welding cast iron...joe

the rods he sell are i think very close to the rods i use the weld mold 700 rod work very good and welded many blocks with it and i will add my welds look a hell of alot better than his