Welding Cast Iron
Thread Starter
Race Director
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From: CO
Welding Cast Iron
I have a cracked exhaust manifold (cast). My friend who has many differnt types of welders and has been doing it for quite some time says that he can weld the cast iron and fix the crack.
When I mention this to mechanics they kind of look at me funny and say "cast iron? can't be done".
So my question is ... can it?
My friend said that you have to get it really hot like 2000 degrees or something. NOt sure if I should raise the
flag or let him at it and see how it goes. He is a good aluminum welder as well as stainless and all that jazz. His dad welded the stainless tanks at Budweiser for quite a few years so I think he knows his stuff.
When I mention this to mechanics they kind of look at me funny and say "cast iron? can't be done".
So my question is ... can it?
My friend said that you have to get it really hot like 2000 degrees or something. NOt sure if I should raise the
flag or let him at it and see how it goes. He is a good aluminum welder as well as stainless and all that jazz. His dad welded the stainless tanks at Budweiser for quite a few years so I think he knows his stuff.
Race Director
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From: Forked River NJ
Yes I have seen it done many times. I was in a tool show a couple of months ago and there was a guy across the aisle tha twas doing just that. He had a cast iron exhaust manifold that had cracked in half and he was welding it back together. If he is a good welder and knows his stuff it can be done.
Safety Car
Joined: Oct 1999
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From: NorCal
Yes and No
Cast welding is an art. Low temp stuff like blocks and heads is no problem "if" the welder know his stuff. The only guy that did work for me recently passed away (major bummer!), but his proccess was this: He cast up his own blended arc welding rod, heated the work piece in a pottery oven, and then CAREFULLY welded the crack. The trick is to keep the work area a consistant temprature to prevent further cracking adjacent to the fix. It would go back in the oven two or three times. No one (to my knowledge) has successfully been able to weld cracked exhaust manifolds because of the heat they are subjected to. Used manifolds have been cycled (heated and cooled) so many times it changes the iron somehow and makes it almost impossible to weld. Often if one is cracked, you'll notice that the iron has crystalized and comes apart in crumbs, and is not repairable. Hope this helps.
Also, I recommend headers!
Hans
Also, I recommend headers!
Hans
Safety Car
Joined: Oct 1999
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From: NorCal
Originally Posted by Gordonm
Yes I have seen it done many times. I was in a tool show a couple of months ago and there was a guy across the aisle tha twas doing just that. He had a cast iron exhaust manifold that had cracked in half and he was welding it back together. If he is a good welder and knows his stuff it can be done.
Hans
Thread Starter
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From: CO
Originally Posted by Wrencher
Also, I recommend headers!
I was thinking about just letting him weld my original manifold and then I could just resell the header. Nothing like stock to fit correctly. Makes me think twice about headers for the Vette.
A stock manifold from honda is 260 bucks. Used I found one for 160. The Stainless header (its nice) was 90. I am on a budget or I would have just got the stock manifold.
Oh and im not trying to rice out the Honda by any means, the tailpipe is and will remain stock. Just trying to fix annoying exhaust leaks.
From the response I have gotten it looks like it IS possible. The metal is not crystalized or breaking apart, just a crack. So I will have him give it a shot.
Last edited by flood; Oct 5, 2004 at 02:39 PM.
Safety Car
Joined: Oct 1999
Posts: 4,101
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From: NorCal
Ah ha!
Good 'ol Hondas. They didn't vent the shield properly (Toyota 4 banger trucks do this too), it builds WAY to much heat and they crack! Neat, huh? Cut a couple of slots (louvers) in the tin cover to prevent a repeat. Toyota sells the louvered cover for their 20-22R engines. I'll stick with Subaru for my wife's daily driver. Heck, I don't have to work on it!
Hans
Hans
Thread Starter
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From: CO
Originally Posted by Wrencher
Good 'ol Hondas. They didn't vent the shield properly (Toyota 4 banger trucks do this too), it builds WAY to much heat and they crack! Neat, huh? Cut a couple of slots (louvers) in the tin cover to prevent a repeat.
Team Owner
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From: Here to make friends
St. Jude Donor '11, '16-'17
Certain types of cast iron (white cast iron for example) cannot be welded, but I'm pretty sure an exhaust manifold can be. There is definitely a technique though.
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Instructor
Joined: Apr 2004
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From: Grand Island NY
Cast iron does not get crumbly from heating and cooling in fact its extremely sable that’s why they use it for blocks, heads, manifolds ect. There is no such a material as white cast iron you must be thinking of die cast or pot metal completely different animal. Any competent welder can weld cast iron.
Le Mans Master
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From: Little Rock AR
Team Owner
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From: Here to make friends
St. Jude Donor '11, '16-'17
Originally Posted by Philvet
There is no such a material as white cast iron you must be thinking of die cast or pot metal completely different animal..
http://www.britannica.com/ebi/article?tocId=202942
http://www.matter.org.uk/glossary/detail.asp?dbid=521
Last edited by The_Dude; Oct 5, 2004 at 04:16 PM.
Race Director
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From: Waterloo ontario Canada
Originally Posted by The_Dude
No, I am thinking of white cast iron.
http://www.britannica.com/ebi/article?tocId=202942
http://www.matter.org.uk/glossary/detail.asp?dbid=521
http://www.britannica.com/ebi/article?tocId=202942
http://www.matter.org.uk/glossary/detail.asp?dbid=521
Cast iron can be welded with nickle rod but brazing with golden rod and the proper flux is very successful.
Team Owner
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From: Here to make friends
St. Jude Donor '11, '16-'17
Now we're getting off topic, but,
http://www.twi.co.uk/j32k/protected/band_3/jk25.html
White cast iron which is very hard and contains iron carbides, is normally considered to be unweldable.
Melting Slicks
Joined: May 2001
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From: May help you? You can sure as hell try!
Just looking through a welding manual the other day. Cast iron CAN be welded but because of it's brittle nature it doesn't take to well to the localized heat involved in most kinds of welding so any cracks just propagate away from the area being welded. The entire casting must be heated uniformly before being welded in order to avoid the highly localized expansion at the hot area near the weld. The welding manual goes on to recommend brazing as an alternative as it doesn't require as high temperatures. Nickel welding rod is recommended if welding is necessary.
Safety Car
Joined: Oct 1999
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From: NorCal
Originally Posted by Philvet
Cast iron does not get crumbly from heating and cooling in fact its extremely sable that’s why they use it for blocks, heads, manifolds ect. There is no such a material as white cast iron you must be thinking of die cast or pot metal completely different animal. Any competent welder can weld cast iron.
We see a bunch of this in Norcal, surely due to the extreme (100 +)summer temps and the heat riser on that side.
Hans
Burning Brakes
Joined: Oct 2004
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From: Grants Pass Oregon
Cast welding
Take it from a welder who worked in the ship yard at charleston S.C.
Originally Posted by glen242
Repaired cast iron manifolds, in the old days, by brazing. Worked like a charm.
Burning Brakes
Joined: Feb 2004
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From: Ville de la Baie Quebec. A winner is just a loser who tried again.
I've welded many exhauste manifolds with excelent results,, weather with a stick or tig,,, the secret is pre-heat the whole part to about 500 to 600 deg, weld, and place it back in the oven and turn off the heat, let cool down 24hrs, you can allso bury it in asbestos powder, or even sand work good,, the idee is to let it cool very slowly and evenly. You have to make sure you have the proper welding rod. 
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by stingr69