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Discussion Starter #1
Did a search and found zip....

Can a cast iron exhuast manifold be welded ? Looking to weld a hard to find/replace early diesel engine manifold. Crack was due to a motor mount failure and bump stop missing.
The crack is around the collector outlet and is cracked 75% of the way around the pipe. It can be taken off and cleaned and prepped prior to welding.
Can it be welded satisfactorily ?

bennett
 

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vee it out and braze it....should last a long time if you clean it up good..
 

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Yes... I have brazed these. depending on how rotten the thing is will determine if it will hold or not. Youll know what kinda shape its in when you start to weld it.. Also clamp it down so it want draw on ya from the heat...
 

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If you take it off to weld it or braze it I would think that you had better bolt it to a heavy plaet to keep it all streight during and after adding all that heat or it may warp.
 

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Discussion Starter #5
85 Chevota said:
vee it out and braze it....should last a long time if you clean it up good..
Do you mean Braze it with "brass" ?

Any particular flux better than another? Maybe I should braze it while it's on.. I can get to most of it...then take it off and finish?
 

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It can be done just take your time and pay extra atention to the prep work and remember it is not just mild steel so it should not be treated as such. Preheat and cooling rate shuld be controled not too much to fast for either, try to heat and cool it evenly.
 

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bennett said:


Do you mean Braze it with "brass" ?

Any particular flux better than another? Maybe I should braze it while it's on.. I can get to most of it...then take it off and finish?
Brazing is actually bronze rod, but if you go to your local welding shop and ask for brazing rod they will know what you mean. I have had the best luck with paste type brazing flux. Apparently this is the same as used for silver solder. Borax works too. Be careful of pouring on the heat because if it gets too hot and burns the flux off and oxidizes the iron, you will have togrind it out and start over. It would be best if you could braze it w/o removing the part as long as youdon't fry anything else.

It has held up on my cracked exhaust manifold for 6 years now.
 

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i much prefere to stick weld it or tig it, you will need to grind it as stated already. go to you local welding shop and see what the offer to do the job usally a very high nickle rod. and practice on something else till you get the hang of it. and that goes for brazing it also. or just pony up and take it to someone who has done it before. mike
 

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yeah I second that, if its truly rare don't mess with it, take it to a pro and have it welded, high nickle rod and pre-post heat treatments will match the stock strength.
 

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The best way to weld Cast Iron (exhaust manifolds) is to use the Acetalyne (gas weld) process. You can buy Cast Iron Rod (most often square) and Cast Flux. This rod works much better than Bronze due to the material cpmponents being exactly the same. Cast manifolds expand and contract more than mormal cast applications due to the extreme heating and cooling temperature differences. The Bronze does not have the same elasticity (much more) than Cast Iron and will seperate (crack) most often. If you are not experienced with castings and cast welding, I would recommend a reputable shop with casting experience.
 

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I worked at a shop one time that had a high tech oxy-acetylene torch that had a bottle of powdered nickel mounted to it.

There was a button you pushed that would inject the fine powder into the flame and spray the molten metal into the heated Vee'd out area in the casting. We used it to repair cast iron exhaust and intake manifolds quite often.

It was very controllable and you could build the weld up as much or as little as needed. Last I checked the set-up was invented and manufactured by someone in So Cal.

There were also other powdered metals in the kit.
 

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I welded the cast manifold in my DD with a mig and the steel wire I always have in there. It's been a year with no problems. I ground a V along the crack and did a two pass weld in 2" long chunks. I would weld, then let it cool for a while, then weld the opposite side and cool, etc.. It worked great, no leaks or warping.

I'm not saying anyone here is wrong, I'm certainly no expert welder. I just figgured I'd mention it since it worked fine for me. Of course, I could get a replacement for less than $200, so I didn't have anything to loose by trying it.
 

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I have also used a mig on cast iron manifolds with no problems. I even cut one up into small pieces, re-arranged the pieces and welded it all back together. It has been like that for 5 years.

I did have it bolted to a junk head when I was tacking the pieces back together.

I didn't take any special precautions when cooling it. If I remember right it was in the middle of summer (hot anyways)
 

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you can stick weld it with nickel rod:rolleyes:
 
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