TIG weld a crack in a cast iron manifold?

[soundcontrol]

A crack in an cast iron exhaust manifold. Is it possible to TIG weld this? Googled but I get many different opinions and don't know what is correct. I know that I should drill the ends to stop the crack. if TIG is OK, should I preheat it? What material should I weld with? I can use a regular stick on my machine also, if thats better. Crack is about 1,5 inch long.
 

[734406pk]

Try this site for info:
http://muggyweld.com/cast-iron-manifold-repair

Preheat is necessary in addition to the correct electrode. Check out the video, this process works great. Hope this info helps.

[soundcontrol]

Great, I'm gonna try that. Thanks!
I want to a swap meet today and saw a guy using a Dillon gas welder to repair cast iron also, he used a special cast iron rod and dipped it in something before welding.

[johns cuda shop]

I have had good luck in heli arc welding cast iron with silicon bronze rod, depends how bad the crack is and how clean the metal. make sure you have the part bolted to something flat and strong so it doesnt warp. preheating and slow cooling is a must.

[jimynick]

Probably not as comprehensive as the prior replies, but we welded a broken off chunk of a cast iron grate by heating it red hot (after first cleaning it) and then migging it, then we re-heated a slightly larger area than the repair again red hot and let it air cool. It's been in the BBQ and heat cycled dozens of times and no issues at all. Just my 

[734406pk]

Great, I'm gonna try that. Thanks!
I want to a swap meet today and saw a guy using a Dillon gas welder to repair cast iron also, he used a special cast iron rod and dipped it in something before welding.

The Dillon torch is another good alternative. No electric needed, but definitely pre-heat cast iron for welding. Brazing with fluxed filler rod works, but you want a color match of the weld area so it appears undamaged i assume. Nickel arc/gas rod made for cast iron repair would be best for this repair IMO. With a little grinding and sanding, the weld area will look untouched.

[YellowThumper]

Yes mount it to something solid. Heat it up for a good period of time. Not just get it hot and stick it. Weld it. Don't do too much and over heat it. Bit at a time. And then maintain overall heat for a while also. Certain weld projects our welder does he puts into a box of sand and closes it up. That way it will slowly cool over a few hours.

Good luck
Mike

[734406pk]

Yes mount it to something solid. Heat it up for a good period of time. Not just get it hot and stick it. Weld it. Don't do too much and over heat it. Bit at a time. And then maintain overall heat for a while also. Certain weld projects our welder does he puts into a box of sand and closes it up. That way it will slowly cool over a few hours.

Good luck
Mike

I place the casting in a galvanized garbage pail 1/2 full of sand then add the other 1/2 over the casting in the pail. Let it cool for 24 hrs. 9 out of 10 times its good to go.

[AussieMark]

You could try metal stitching what happens is you drill and tap a hole at the start of the crack and screw in a tapered cast iron plug then another hole next to it and slightly into the plug, tap it and screw in another plug and so on until you've covered the length of the crack with plugs that are interlocked this stops them from working loose. They are called "A" plugs and you can get "B" plugs but they are larger. I have seen many cracks in engine blocks and cylinder heads repaired using this method you will need the correct tap to suit the plugs and then shorten the plugs so you don't have too much hanging inside the manifold or it may upset the exhaust flow Google Lock-N-Stitch for more info it's a lot easier and not as risky as welding I have seen many welds crack again along side the weld the only guaranteed way to weld it is heat it in a furnace until it is glowing red, oxy weld it with a cast iron rod then cool it by very gradually reducing the temperature of the furnace over many hours.

[soundcontrol]

I got some cast iron sticks for my TIG and did a rough test on a scrap manifold, not too bad, easy to get holes though, I guess that is from contamination of the material. Like when I tried to TIG weld a galvanized part, impossible. The TIG is very sensitive to contamination. I did not preheat much, just a little bit (a minute) with a gas torch, and did not put it in sand or anything, just wanted to see if it would crack because of that. I did hit it with a hammer a few times after welding. Think I'm ready to try the cracked manifold now. I will be more careful with that, clean it good, preheat and put it in sand.


If I preheat a lot, I could mount it to the head (it's loose) so it dosn't warp, is that a good idea?

[734406pk]

I would vee out the crack a little more (45 degrees or so).  You don't need to preheat so much as to raise a warpage an issue. Preheat and weld then submerge in HOT sand and let it cool slowly. You should be fine.

[soundcontrol]

I would vee out the crack a little more (45 degrees or so).  You don't need to preheat so much as to raise a warpage an issue. Preheat and weld then submerge in HOT sand and let it cool slowly. You should be fine.

Yes, on the real manifold I'll do that, I just made a cut with my grinder in this junk manifold to test weld and see how it would work out. The real crack goes almost 360 around the manifold and it held together with just about 1/2" of material, if I tap on it it will be in 2 pieces. Thats why I was thinking of mounting it on the head while welding, at least the part I can reach when its mounted.

[734406pk]

Yes, on the real manifold I'll do that, I just made a cut with my grinder in this junk manifold to test weld and see how it would work out. The real crack goes almost 360 around the manifold and it held together with just about 1/2" of material, if I tap on it it will be in 2 pieces. Thats why I was thinking of mounting it on the head while welding, at least the part I can reach when its mounted.

Ah, I see. Yes you can bolt the exhaust manifold to the head to maintain alignment or use a piece of 3/8"-1/2" flat stock bolted across the gasket surface. I would prep the weld area, tack weld every 1/2"-3/4" to minimize distortion then fill in between the tacks. Good Luck!

[soundcontrol]

I did it now, it was very difficult, the test maifold I welded on was much easier. This one had to be another type of cast iron.( Its an old one, a -55 T-Bird manifold.) Looks OK now, but during the welding it did not feel like the weld connected to the manifold that well, kinda like soldering on a surface that don't let the solder flow out. Did it right, drilled the ends, made a V shape in the crack, preheated well, cooled off in sand that I heated up....(in a styrodoam box). I suspect it will crack again, time will tell, I tried my best. Maybe the goast of Henry Ford didn't like a Mopar guy welding on his stuff...

[AARTA340]

Interesting--let us know of any updates, OK