Farmall B with welded crack in block

How much would it devalue the tractor with a welded block? It "doesn't leak oil into coolant or coolant into oil," but he is trying to sell the tractor...He said it does leak a little coolant to the outside. I have heard of these blocks cracking before bc they are part of the frame.
I would probably gouge out the weld and have it rewelded and see if I can make it look tastefull or barely noticable and not leak. A local welding shop does EXCELLENT work on cast so I am not too worried.
The tractor seems pretty cheap to be in fair and operating condition so I am a little nervous. The guy doesn't know tractors, so that could be the other cause. He doesn't even know what model it is, but the picture he sent is a dead giveaway. He got it to do food plot stuff and mow etc.
I think I have tractor buying fever! I better just hook up the trailer and buy it before somebody else does.

There are many that are cracked to the outside with no issues. That said, it may be that there are structural cracks internally. If the price is right, and your welder good, it is probably a go. The worst case is to find a good 123 engine with a hydraulic pump and make it nice, if it becomes irreparable. Jim

If you get the tractor and cosmetic appearances are important to you, grind down the visible weld and CLEAN up the area, then slather a coat of epoxy over it and, as it's partially hardened, press a piece of sandpaper against the epoxy to create a surface texture similar to the cast iron block.

PRESTO... no more leaks AND a nearly invisible repair.

As Bob and Jim have noted, it depends on what's gone before. If the crack is on the port side of the motor, generally in the area where the carburetor hangs, that's not uncommon, and is generally the result of a freeze-up. There are many good fixes on that type of crack out there, but also many not so good. If it's that type of crack, and the leak is only a slow seep, the epoxy fix could very well take care of it, as there's no internal pressure on the cooling jacket on the B. If it was a very bad job fixing that type of crack to begin with, it might be better to have whatever repair was done ground out and done over as in your initial thought.

If it were a stress crack, then you would need to go over the block with a fine-tooth comb and consider having it magna-fluxed to check for cracks in the webbing on top of the block where it mates to the head gasket, as well as the lower end where the sleeves seal.

Those blocks, though, were beefed up in the right places so that responsible use would not overstress their capcity as frame components. Are there any other repairs or welds on the block, like on the ears where it bolts to the front casting or the torque tube? That might suggest your crack could be due to stress.

If the price is right, then get it. It is a roll of the dice whether the block is salvagable or not, but the rest of the tractor may be worth it.

If you dont' have a B, or this B has parts you want........get it.

I fixed one yrs ago ground it smooth and put some rubber cement that they use holding your windsheild. Its been several yrs and will not leak. Tractor has been on several 180mi tractor rides. You can also use JB it works also some fiberglass will also work as we are just talking a weep correct. Mine had been welded but water fan out as fast as you could pour. Grind it clean is important.

...we are just talking a weep correct...

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Correct, the seller said it was a small weep. I'll see on Sunday when I go to pick it up.