Exhaust manifold crack repair?

[Lowhound]

I purchased a set HP magnum exhaust manifolds recently and they looked good. But upon blasting them to paint I noticed about a 6 inch long crack in the passenger side manifold. Is there a proper way for it to be repaired. I cant find anyone in my area that will guarantee their work on it. The guy I bought them from said he will pay to get it fixed or replace it. But as of now neither of us have found a possible replacement.

 

[benno440]

take it to a welding joint they should be able to weld up the cast iron easily enough, if not then there not good welders

 

[62 Dart Convertible]

I can understand welders not wanting to guarantee the work, they've probably been stung before. What looks like a small welding job can quickly become a large welding job as cracks can grow and appear elsewhere during welding. If you find a welder that has experience, you just need to hand it over and perhaps pray a little.

Welding cast iron is not that difficult. It just involves preheating, using the right rods and slow cooling, but it carries some risk.

If the seller is willing to pay for the repair, then it is him taking the risk, not you isn't it?

 

[bee71]

Try this.
http://www.ebay.com/itm/Mopar-383-4...Parts_Accessories&hash=item27e5973ffc&vxp=mtr

 

[kb67mopar]

I welded a cast iron manifold last year, its not too hard. Just pre-heat, weld, and post heat and slowly cool it. After that you should be good to go. But I would never expect a warranty for it. You never know the reason it cracked in the first place, casting inclusion, improper torque sequence, warpage....he can't plan for that but at this point what do you have to lose?

 

[D575]

proper rod, grinding, pre heat, post heat. slow cool down, last one I did , I made and oven out of fire brick and wrapped it up in a welding blanket. after welding, will need to machine mating surfaces flat.

I have had great success with Exercon #130 Cast-weld HPM
AC / DC

 

[trimmer]

lowhound, Dover Cylinder Head in Atlanta, Ga. will repair those and you will be happy with their repair.

 

[5.7 hemi]

Got to use a nickel rod and follow what others have said about pre-heat, and slow cooling.

 

[ZR9B]

the guy I know puts his in a box of sand overnight after welding.

 

[Meep-Meep]

The best way to weld cast iron is to gas weld it with a special poured cast rod. Preheat to at least 450F (hotter the better, like 700) and make sure to cool it slowly when done. I made a big BBQ for this purpose and use charcoal to preheat it. Smokes like crazy because of the charcoal so use a respirator, and when you're done just close the lid tight, seal off the vents, and let the coals simmer down.

 

[Photon440]

I've had success with the hot method using ni-rod, but there's also this cold method that I've been interested in - haven't tried it yet.

http://www.weldingtipsandtricks.com/cold-welding-cast-iron-with-mig.html

 

[68GTX440]

I have had great success welding them also. I start with drilling into the manifold at each end of the crack. (not completely through about half way in or less) This will stop the crack from spreading. Pre heat, weld then slow cool. I use gas weld with a flux coated brazing rod.

 

[steve from staten island]

Ive been a certified welder well over 30 years now and ive done some cast iron,not a lot but enough during that time. Im not up on my metallurgy but not all cast irons are the same. Some dont weld all that well and its usually the cheaper made casts like exhaust manifolds. You guys all are on the money with the post and pre heat and the gas welding is something to look into but i doubt many welders would warranty the work and what they charge should reflect that. That Meep is a bright young man.