cracked block repair

Al Bass

Al Bass

Senior Member
When I first rebuilt my engine I found a crack in the block and had it welded, but when it was reasembled it still leaked. I asked for suggestions on the forum and was told to try JB weld. So the second time I rebuilt my engine from a bad babbett job :mad: I heatted up the area of the crack with a torch to make sure it was totally dry and used my dremel to roughen up the area and applied the JB weld. It has about 3000 miles on it now and is holding up fine.
Thanks for the advice :)
 

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Hi Al,

J. B. weld & similar products are great for similar applications.

Cutting "slight" recesses in sides of metal joints with a Dremel tool, or drilling in "slight" recesses in sides of joints with a drill, or forming joints similar to dovetail joints can greatly increase material attachment & holding power.

If one were to investigage many material application failures, one would often find improper surface preparation & improper cleaniness of metal surfaces.
 
I run a materials laboratory....one of our customers, a major adhesives company, wanted to market their own epoxy, so we started by testing all of the available products on the consumer market (that we could buy locally) for strength and durability on all sorts of surfaces. JB Weld was simply the best we found. It's been sold for so many decades now and you really can't beat it. There are adhesives that cure faster but none that outperform it. I was really impressed. And H.L. is completely right; surface preparation is so critical: clean, clean, clean until water sheets off of it. And roughen the surface as well. I always like to apply some heat to speed cure; a hair dryer or light bulb works great. Also it lowers the adhesive viscosity and lets in flow into the peaks and valleys of the roughened surface. Looks better and works better.
 
i bought a 8n ford tractor back in the 70's, with a hole in the block and the connecting rod was sitting on the block and oil pan flange, rod cap gone. The hole was about 1 1/2 ", my uncle and i welded it using a 3/16" steel plate to fill the hole, we used stainless rod arc welding, i was welding about 1/2" at a time my uncle was cooling and peening with ball peen hammer, worked like a champ, we also used a material simler to jb weld, it's still there, no problem, this was not in the water side of the block .

jim, ky
 
The only reason a weld would crack is if the person who had welded it for you did not use the proper cast iron rod. I have seen this in all areas of fabrication through the years. "Look, I used the mig and it's holding fine". Thats when i would whack whatever it was with a hammer or mallet to prove my point and walk away laughing.
 
Yeah and no, Kenny, I've welded some stuff together with Ni-rod some held and some didn't and I've welded some stuff with S.S. rod and it worked fine and some didn't. A lot depends on the iron and how contaminated with carbon it is. The best one I ever ran into was a Cat. head that was cracked. So my friend Bill heated it to 1200 deg. and poured 6010 into it. 6010 is a very violent arc and it will burn out a lot of carbon. AFAIK, It's still holding. With C.I., you've got to be flexible.
Terry





kenny5074 said:
The only reason a weld would crack is if the person who had welded it for you did not use the proper cast iron rod. I have seen this in all areas of fabrication through the years. "Look, I used the mig and it's holding fine". Thats when i would whack whatever it was with a hammer or mallet to prove my point and walk away laughing.
Click to expand...
 
Al Bass said:
When I first rebuilt my engine I found a crack in the block and had it welded, but when it was reasembled it still leaked. I asked for suggestions on the forum and was told to try JB weld. So the second time I rebuilt my engine from a bad babbett job :mad: I heatted up the area of the crack with a torch to make sure it was totally dry and used my dremel to roughen up the area and applied the JB weld. It has about 3000 miles on it now and is holding up fine.
Thanks for the advice :)
Click to expand...
Thanks for that Al, I have a block with exactly the same crack, and is otherwise pretty good. Now that you have proven it will work I'll give it a go!
Cheers!
 
Here's what happens when JB weld goes wrong.
It seems someone tried to fix this block with JB weld,then braze and then try to pin it . They threw everything at it but the kitchen sink.

It was a mess. The one thing no one has mentioned on this post is "metal stitching" which we do here successfully and have repaired this block doing so.
Once the repair is done it isn't obvious under the paint.
http://www.jandm-machine.com/metalStitching.html
 

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