welding cast iron

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Princess Valiant

Princess Valiant

A.K.A. Rainy Day Auto
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if i had an exhaust manifold that is cracked .....say a tab is broken .....can i weld it with a mig welder??

i have a lincoln mig welder and i was going to try it but i am not sure if cast iron is something i can do or if i should just not waste my time trying.

any input on welding cast iron?
 
Mig?...it will never never happen, no way, no how. GAS weld it?...I do it all the time. No oven, no preheat and mild steel filler rod. There's a technique......
 
no it wont work rani . do you have a electric arc welder? if so it would be my choice. cast welding takes more prep and welding a tab on wont be easy if you want more tips on how to attempt this pm me
 
well truth be told .....i saw this on ebay and it is listed for mega cheap so i was thinking if i could fix it and use it i would get it ......but just as i suspected ....there is a reason its so cheap and i would probably save myself a head ache and whole bunch of work if i just pretend i never saw it and wait for a good one to come through.


http://www.ebay.com/itm/Mopar-Big-B...n-/321249209831?&_trksid=p2056016.m2518.l4276
 

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I've mig welded exhaust manifolds that I got a little to aggressive porting and broke through the casting. I just "stacked" the beads until I closed the hole up.

then went back to report it to keep it flowing better. Man, the weld is much harder to grind than just plain casting.


Why do you other guys say that it can't be done?
 
That one could be a challenge to re attach that tab.


Rani, stop going for the cheap stuff.... Nothing's free... There's a reason that it's so cheap....
 
Who's holding the manifold in the picture? That doesn't look like your hand....
 
Take it to a shop and have it spray welded. Or use a stick welder with a shartanium rod . First pass with shartanium will look terrible second pass will get perfect. Just the nature of the beast. Yes it will mig weld if you heat it but will not be as strong if done that way. Gas welding does work but there is a knack to it as stated. Practice on something as another manifold you don't need. Years back I used old coat hangers and welding flux.

I had Shady dell break a X block on me. That is when I learned to use shartanium. The best home method. Spray weld is the strongest My son does it at the machine shop now but materials (Powder) is very expensive. Something such as a tab should not be done any other way. Very strong and will take a load through torque. Steve
 
krazykuda said:
Who's holding the manifold in the picture? That doesn't look like your hand....
Click to expand...


thats an ebay auction ...not even mine ....click the link thats there ....some guy in North Carolina ...i dont know LOL
 
A local welding shop could fix that easily. Clamp the piece in place, grind a V in the break, Arc weld with nickel rod.
 
I've welded exhaust manifolds with a Mig before, it's a nightmare but it can be done. To get it to burn in, I had to crank the heat setting up high and then the longer I welded the better it burned in. Which makes sense, since you're supposed to preheat cast iron before welding it.
 
krazykuda said:
I've mig welded exhaust manifolds that I got a little to aggressive porting and broke through the casting. I just "stacked" the beads until I closed the hole up.

then went back to report it to keep it flowing better. Man, the weld is much harder to grind than just plain casting.


Why do you other guys say that it can't be done?
Click to expand...

Mig welding closed a hole is much different than attaching a broken ear. The hole is surrounded by super thin casting, and it won't be subjected to torsional loading the way a cracked structural part would be.
As for the "technique", I actually developed it myself many years ago. What I do is heat both sides of the crack evenly to molten. Then, I poke and swirl both sides of the pool with a mild steel rod while focusing most of the heat on the casting. It's a very slow go with this...and it won't work on something like a freeze crack where both ends of the crack are within the boarders of the casting. But, for something like a broken ear, or adding something like a boss, it works every time.
 
My neighbor makes a jig for the part, heats jig and heats the part w a flare tip slowly and evey until very hot , he said he V the crack also. Weld w nickel rod. He is a brilliant welder and I doubt most could duplicate that process w/o risking warp or more cracks.

You would prob have to have the manifold surfaced anyway afte the work. May as well have a reputable shop weld then surface it.
 
I would put it In your oven on a head turn it on the highest setting. have sum old rags blancets what ever stick it in a cheap cooler and hall as to the man that's going to weld it!!!and that man will be at your friendly nabor hood construction co.im sure they have the rods and tools to do it.but I would take and get it all lined up before doing it.as If you didn't know that all ready!!:violent1:than get it back home and in the oven to get back up to temp then just turn the oven off and let set till you can touch with hand...and this could be days! unless you have a lot to do its not worth buying the stuff to do it yourself.the last time I but these rods they were 6.00 bucks each..buy a 50 pond box of them:banghead: unless I was getting riped but at the time I didn't care!!!hope this is a help...........Artie
 
No need for going out of your way. Just get the right rod.

[ame="http://www.youtube.com/watch?feature=player_embedded&v=ejGttywG98w"]How to Weld a Cast Iron Exhaust Manifold - YouTube[/ame]
 
I did this same repair by brazing it, i preheated it , then got it cherry red and brazed it . It worked perfect and its still running fine 3 years later
 
I've mig welded a manifold, took and cut the down pipe off turned it and welded it back on, this was a 1978 360 manifold, it never broke and that was 8 years ago
 
I have had some success mig welding cast and a few failures too. Cast can be a real pain because of the verying amounts of carbon. Exhaust manifolds are especially unpredictable because of all the heat/ cool cycles. I usually arc weld cast with ni-arc rod but have recently experimented with grooving out the area adequately and then heating the manifold to 450-500 degrees in an old gas barbeque. Check with a temp stick. Then run a nice hot bead adding some small diameter ni-arc rod similar to tig welding. Run a bit and hammer it down. Repeat until done. Hopefully you wont hear the dissapointing sound of an additional crack. Make sure you cool it slowly. Practice on Chevy manifolds. A failure or two on those won't cause you to lose any sleep!
 
I just had my son spray weld a manifold back together that had the front port broke off. You couldn't tell where it was welded.

I welded both ears back on the rear of an X-block that Shadydell ruined on me. I used a shartaniun rod . Expensive but Very strong. Nickle works good but brittle next to the weld on butt welds. Also very noticeable.
 
My uncle has welded (gas torch and special filler rod) many iron manifolds, most of which saw use WAY tougher than anything anyone here will manage! (Think: an hour or more at WOT, with 35+psi in the exhaust and 1000 degree exhaust temps.) They usually lasted until the engine was ready for an overhaul.
 
As was mentioned get a competent machine shop to do the repairs. I had a BB one which was broke in half. I had my local machine shop weld it and surface it, looked great, worked good and held up just fine. Once painted could not even tell other than one of the numbers being missing where the break/weld was
 
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