my rev hard downpipe is cracked alost all the way around the flange, hanging on by like 1 inch. and the pipe needs to be welded to the origonal exhaust. any ideas?

 

welding to cast in not suggested, but if you do, it will have to be TIG Welded with high nickel content filler, and should be preheated before welding. then slowly cooled.

 

you can also stick weld cast iron...TIG is not the only way...but yes whatever filler you use must have a high nickel content

 

Also it is recomended to Pre-Heat the cast with a torch, then weld, and then Slowly cool it, put it in a bucket of sand and let it sit. It will take a long time, but will minimze the chances of cracking.

FYI, on my first HMT Turbo I welded a 3/4 adaptor plate to my 14b turbo with a standard 6013 Arc rod, no pre-heat, and no cracks, still holds after 2 years.

 

i'm here to represent the brazing crew of cast iron welders. I have brazed a few cracks that have worked amazingly. You need to drill out either end of the crack to relieve the stress though. Also follow everyone elses pre/post heating instructions.

 

so, heat it up with a blow torch first (or maby an oven, thats wat my friend said) and they weld it very carefully and then let it sit in the 85degree temp air for an hour or 2?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by skiwithcars &raquo;</TD></TR><TR><TD CLASS="quote">so, heat it up with a blow torch first (or maby an oven, thats wat my friend said) and they weld it very carefully and then let it sit in the 85degree temp air for an hour or 2?</TD></TR></TABLE>

pack it in sand or DE or fiberglass over night. It will keep is much hotter than open air.

 

I am not reccomending this, but it is possisible to weld cast iron with a mig. I have done it on 3 different occasions and had some success. The only problem is that you will ruin a ton of welder tips and it takes a while to accomplish. First i heated the cast iron up with my blow torch, I welded it to a stainless steel flange. Then i used mild steel wire and an argon cO2 mixture. To weld it keep a very close gap between the tip and the piece. Watch through the mask and make sure it doesnt start forming on the tip. You will mess this up a few times before you get the hang of it. You will only be able to weld a half inch at a time. If you weld more than that you will mess the tip up and have to replace it. The welder almost acts like a tig welder because it almost throws the arc out of the gun. Good luck, but only do this if it is a last resort.
Thanks
-Drew

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Electron_LS-Vtec &raquo;</TD></TR><TR><TD CLASS="quote">I am not reccomending this, but it is possisible to weld cast iron with a mig. I have done it on 3 different occasions and had some success. The only problem is that you will ruin a ton of welder tips and it takes a while to accomplish. First i heated the cast iron up with my blow torch, I welded it to a stainless steel flange. Then i used mild steel wire and an argon cO2 mixture. To weld it keep a very close gap between the tip and the piece. Watch through the mask and make sure it doesnt start forming on the tip. You will mess this up a few times before you get the hang of it. You will only be able to weld a half inch at a time. If you weld more than that you will mess the tip up and have to replace it. The welder almost acts like a tig welder because it almost throws the arc out of the gun. Good luck, but only do this if it is a last resort.
Thanks
-Drew </TD></TR></TABLE>

as he said, last resort. Half of my repairs are loads of cracks from people migging on cast.