Cracked Block?

You are correct....freeze crack....quite common on the D2's and D4's in that location. Repairs, either welding or epoxy seem to hold up quite well. Not normally a very stressed area of the block.

I've taken a cracked block and drilled a hole at each end of the crack to stop it from spreading, then heated the block, at the crack, cherry red and used a mig welder to weld it. I ground out the crack a little with a hand grinder and never had a problem. This entire procedure takes about an hour or less.
So far, I've had very good luck with cast and a mig welder. I can hardly use my stick welder anymore.

I bought D2 5J3691 (1941) in 1969, with a plate bolted over the hole in the water jacket. It was probably one of the reasons I got the Cat for a short song. I've never touched it. It has never leaked or caused any problem. The Cat is still in service after 40 years with me, and the plate is just black steel, probably with the gasket completely covering the face of the plate. I'm not sure, I've never messed with it.😊

The weld looks like a high nickel rod was used. It also appears that they used a stitch technique. I'm guessing a stick welder was used.

Like I said in my op it hasn't been a problem for thirty years and I don't see it being a problem for another thirty.

Here is my cracked D4400. What a ugly weld. But it wasn't leaking so I guess all is well.

[img]http://c2.ac-images.myspacecdn.com/images02/27/l_7dd99833817f4149a4f3607e4ed9582d.jpg[/img]

Give it a paint job and it will look like nothing ever happened to it. As long as it doesn,t leak then that,s the main thing.