1941 John Deere HN - Investigating Cylinder Head and Engine Block Issues Part 2 of 2

Two days ago is where I left off on the previous blog. Yesterday I ground out the engine block crack. I used a carbide burr on an ancient dremel-type drill motor.

The crack is now filled with JB Weld. I'll let it set up for a day. Then I'll file down the part that is the head gasket sealing surface, but will leave the rest au-naturale.

That brings us up to today, and let me tell you, there's sad news on the HN engine front. This morning I found a lot more freeze damage.

This next photo below is of the front end of the engine block. The center oblong hole is the water jacket and the two square-ish holes next to that one are for the pushrods, so they are part of the crankcase. There are three small cracks between the water jacket and each pushrod hole. That's a bummer. I don't know how I can seal those. I may need to just use a coolant sealer additive.

After finding those cracks on the cylinder block above, I started messing with the head. Whoa.... that's a serious break. The "loose" chunk (it's not really loose) has also raised up its surface that contacts the head gasket. This raised surface will need to be filed down or water will leak even if the cracks are fixed.

After a bit of contemplation, I decided to just delve in and braze up the cracks. I think they are too big to try and fill with JB Weld. I ground out the cracks with an angle grinder and cutoff wheel, then I hit it with the aforementioned grinding burr.

I don't do a lot of brazing but I'm hoping my feeble attempt turned out passable. I won't know if it leaks until I file down the head gasket surface high spots, reinstall the head, and then actually get the engine filled with water.

After what seemed like an eternity of filing, I am calling it done on this head gasket sealing surface. It looks smooth enough to work. The biggest problem, as mentioned above, was that the piece that broke out also tweaked the sealing surface so things weren't flat anymore. I filed, filed, and filed some more until it didn't seem like things were improving to any great degree. It is going back together like this.

The head is back on and torqued down. Pushrods are in, valves are adjusted. Just a few things more and I can try starting this tractor again. Last time it ran, it was only on one cylinder. Hopefully with the work I did it will run on both.

This video below is what I went through to get the tractor started after the "rebuild". It did not want to start, but finally it did. There was still a small leak in the cylinder head but I'm hoping radiator stop-leak will fix that issue.