brazzing

Brazing in areas that aren't "open ended" tend to keep on cracking. You can braze at the top of the block around the water areas with no worries. On cracks you describe I would drill a small hole at the end of the crack, 'V' the crack out a small amount, and apply JB Weld. If it is a 'spider web' crack, I have no recommendations.
 
I guess I'm too old fashioned. I'm still a driller, grinder and brazer.

But, many fellas swear by stuff like JB Weld so maybe its worth a try.
 
The problem with any heat related repair is the shrinkage as the metal cools. I have not brazed any cast iron but have used nickle welding rod to make repairs. The tricks I used were to heat the cast iron and then peen the weld as it cooled to relieve the tension stress and put it into compression. If done right the weld can be reliable. I suspect the brazing would be too and it has the advantage of being a more plastic metal.

A problem with cast iron is the high carbon content, which makes it hard for metal to stick. And it means that the cast iron does not melt to make a weld like steel.

Not too many people around that do brazing or weld repair of cast iron any more. Most of the repair is done by stitching with threaded inserts or using an epoxy type material. If you do decide to use an epoxy material, make sure the cast iron is perfectly clean. Grinding or a rotary wire brush seems to work the best.
 
nkaminar said:
The problem with any heat related repair is the shrinkage as the metal cools. I have not brazed any cast iron but have used nickle welding rod to make repairs. The tricks I used were to heat the cast iron and then peen the weld as it cooled to relieve the tension stress and put it into compression. If done right the weld can be reliable. I suspect the brazing would be too and it has the advantage of being a more plastic metal.

A problem with cast iron is the high carbon content, which makes it hard for metal to stick. And it means that the cast iron does not melt to make a weld like steel.

Not too many people around that do brazing or weld repair of cast iron any more. Most of the repair is done by stitching with threaded inserts or using an epoxy type material. If you do decide to use an epoxy material, make sure the cast iron is perfectly clean. Grinding or a rotary wire brush seems to work the best.
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There is an epoxy product called Belzona 1212 that is designed to be used on engines when the material can't get surgically clean. It is recommended by CAT and other big diesel manufactures when there is a needed field repair.
 
Cast iron is difficult to fusion weld but there are still a few shops that perform these types of repairs. It is usually only done on parts that are unobtainium due to the cost. It is a lot like working in a foundry due to the heat involved. Cast iron is fusion welded with pieces of cast iron that are basically the same or very similar in make up of minerals to the base metal.

If there are new castings being made then I would use those or replace with known good original castings. There is no point in patching parts that can be replaced. I braze stuff as well but limit my cast iron repairs to parts that are very hard to source or just not available. Repairs sometimes require dimensional checks of the part to make sure it will still function as it should. If it can't be restored to original fit after repair then the repair is just not worth the time or materials wasted.
 
I had an A block once that had a couple cracks in the upper eater jacket, on the passenger side. The guy was suppose dot weld it. He is a certified welder, and even does work for the local gas utility Mig, tig, stick...he has the highest certification for new work, and repair. He has an "R - stamp", if you know what that means. Abt 3 weeks later he calls me and tells me he's done. I get over there, and his buddy talked him into groving it out and using radiator solder on it! I WAS TICKED! My moral of the story is try to find a welder you can trust. Other wise the KB weld, or the Belzon 1212.
 
Solder repairs will work too. Done by V'ing out the crack, rubbing copper on V'ed out area or tinning then soldering. One of these days I am going to try it.
 
Try some of the epoxies recommended first.
If that doesn't work, try silver solder RATHER THAN brass. It flows at a much lower temperature.
If that doesn't work, try TIG welding it with ER70 steel rod. This will have to be done by someone familiar with the process though. This would be the strongest repair if it was a structural part.
 
oldredford said:
Anybody tried to braze hair line cracks like under the water pump due to freezing?
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It’s a water pump housing. They are a dime a dozen at swamp meets, and are fairly cheap as new reproductions. Buy ne of those, and put the time and effort into something else.
 
Not that I would use these methods, but the early model A restorer guides give some interesting repair methods I have otherwise never heard of. Including using iron dust to rust the block back together. There's another method that calls for 'sal Ammoniac' and brass powder, I'm assuming for some type of brazing process. If I had the book in front of me it would be helpful. I'm sure somebody else can recall better. Again, I'm not saying I would use the methods of yore' just interesting and topical
 
I took the engine from my first Model A to an old-time machine shop in 1967 to have a crack in the water jacket under the water pump repaired. Their attempts to braze it made the crack run down the driver side of the block. After that, I discovered JB Weld and was able to use that engine for another ~40 years before retiring it a couple of years ago.
 
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