repair of 27 Pontiac block

[boler76]

My 27 Pontiac has had a cracked block that seeps coolant externally, for well over 60 yrs, my question is, there must be a product available now to put in the coolant to stop this leak , it is a non pressurized system, but I do not want to jeopardize the cooling. What are the suggestions? Thanks

[Tinindian]

You can do a stitch repair. About 1/8 of a inch past the end of the crack drill and tap a 3/16 hole. Insert a brass plug. Move along and drill and tap another hole overlapping the first plug by 1/3. Keep on until you are 1/8 " past the other end of the crack. By using a dab of sealant on each plug as you install it your block is fixed. I have seen a good number of repairs done like this and the engines were used for many years with no problems. The first couple I saw were in cars that I was pulling out of the bush where they had sat for a couple of decades. None of them ever leaked.

[boler76]

Thanks for the input Tinindian, i should have mentioned that the crack is on the underside of the block between the 2 heads above were the dist/oilpump mounting bolt is located. Cant get a drill or tap in there, i just thought that there would be some new space age stuff that could be put in coolant to fix from inside, what I have done to fix it so far is clean and use JB Weld while applying vacuum to cooling system, Thanks again for your thoughts

[Tinindian]

This is not going to help your repair but the shop manual suggests what may have caused you damage. There are two longer head bolts which are supposed to be used to hold the horn bracket. If they are used in the corner of the head nearest the middle of the engine and are tightened down enough to make the head gasket seal they will have bottomed out and can break the block at this point.
If you were to pull the heads you should be able to repair the crack as I suggested earlier.

[Xprefix28truck]

Tinindians way is by far the best. BUT there is a good product out there that I have used with great success on older John Deere tractors. It's called K&W Block Sealer. Follow the directions to a T and all will go well.