cast iron welding

fiddleman

Member
I am an Allis collector and my dad and i have some gas engines .Dad bought a Meco engine cheap cause the head was broke out from freezing. He wasn't concerned about this cause he has welded up heads before. Except, when he got it home and looked at it closer , found that the whole bottom of the water jacket under the cylinder is busted out too and most of the pieces are missing.Major repair.I can weld, and i,m gonna try to fix it . I'm not an expert on cast iron welding, but i know there is preheating involved. I saw an ad in a magazine about those magna 770 rods , I think they were called. Sounds like they simplify welding cast,and sound almost too good to be true. Since they are very expensive, I wanted to see if anybody out there has tried them and what kind of luck you had with them? I thank you in advance for any responses.
 
Cast iron welding is not for novices. I have been fooling with the stuff for over 40 years and it still bites me in the hind end every now and then. George Md. is the cast iron expert on this forum. He welds it with oxy-acet. I have done a few pieces myself, but it is very labor intensive and expensive. Cast is not like a lot of other metals, once you have screwed it up,you can't back up and start over.
 
Cast is just fickled. You could have two identical parts to weld and one would weld great and the other seem to just burn up instead of welding. It just depends on the pour. Some of it can have so much impurities in it you can't electric weld it. Not knowing this when you get into it, it would be safer to braze it. To electric weld the parts it's just better to have a professional weld it. They would have the experience to know quick when it was a bad cast and stop.
 


I don't know what your project looks like ,but almost any chunk
of cast is solid enough that it cannot move as the weld from the
arc welder cools. all the noise about keeping it cool while you weld
is noise. The arc is several thousand degrees ,and when that weld
material cools , that contraction has to come from some where and
cast not being ductile ,you have just created a crack. If it is
small enough and you can strip it out completely , you can weld
it with O/A and the cast iron rod. You will need a fire brick
enclosure and a large propane fire ( weed burner ) to heat to
1200 deg ,weld and post heat to 1500 for 15 to 20 minutes .That
way you get a successful weld.
The other method would be lock & stitch plugs , they are better
in most cases the iron tite plugs as they don't spread the pieces
you are working with . Iron tite plugs work well in cyl head cracks.
Being you are missing pieces an old bath tub is a great source
of material , good welding and good drilling for plugs.
Here is a cracked head done with O/A ( before and after ) look
in the link for the steps in that repair and some others.

george

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more repairs
 
Could the bottom/missing pieces be replaced with A36, 1018?

That would simplify the welding, weld with stainless wire mig, or I assume the Magna rods would work.

Probably have to seal it up with JB Weld to water proof it.
 


O/A weld or plug it and most likely won't have to use a sealer.

Your best bet on an engine block is to leave the arc machines
on the shelf.

george
 
Wow. Some awesome responses. Thx everyone.I'm gonna try to post some pictures if I can figure out how to do it. Might take me a while to get to it though.I'm thinkin I might try to braze this thing. I do have some experience with that on smaller projects.
 
Hi, All,

this is a great thread. I, too, have a cracked block (Continental Z134) and was going to do exactly as George MD suggests, except I was going to use a stick welder and nickel rods. I dont have an OA but could obtain one.

I was going to heat the block as described - fire brick and propane - but was iffy on the timing. My plan, which may be a stupid plan, was to walk the temperature up over 10-12 hours and then back down over the same period of time. I had also read that you dont want to take the temp much above 1200 as 1400 is a key temperature for cast iron. The thread above says 1500 and I wondered why.

On other sites I do discuss about keeping the block cool (~100-200 degrees) and making tiny beads so the HAZ is small. This seems to me to be a recipe for disaster as rapid cooling of the weld and HAZ seems guaranteed to weaken it.

If the whole thing ends up ruined - well thats the way it goes. I have a replacement block so this is just for learning and maybe using next time a cracked Z134 comes my way.

thanks for the advice! this thread is terrific

Bill
 

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