Hey all,
I found out that there's a 3" crack in my shortblock between the two freeze-plugs on the drivers-side. Looks like it's there for a long time because of the rust-buildup in that area.
A friend of mine, who works at a truck-shop (Scania), told me about a liquid sealant I could use to close the crack by mixing it with the cooling fluid.
Should I be worried or...thanks for the info.
It concerns a 383 from 65.
What you describe was frequent enough that the factory redesigned the blocks with extra stiffening ribs in 69 or 70 (I forget which year).
It most commonly occurred in very cold climates, which I am guessing was due to the continued stress of expansion differentials of the engine heating from the inside out, while the outside was exceptionally cold/freezing.
The good news is that it doesn't cause any problems other than potential slight coolant loss, but I have heard of freeze plugs coming loose and popping out if it is not repaired.
The ideal method would be to have a welding shop run a bead down the crack, but I would be afraid that the weld would crack unless it was run extensively on both sides of the crack (for the same reason the stock block cracked). I have heard of JB weld, or silicone, used with perfect success.
The problem I see with an internal only sealant is that the expansion differential problem will crack the internal seal much easier than the original cast iron, so I doubt it would do anything other than "gum up" the cooling system.
Were it me, and keep in mind that I have never had the problem happen, so I am only offering a solution that I consider logical, .... I would clean the perimeters of the effected freeze plugs, and a 1/2 inch or more along the crack path. Use about 4 small dabs of JB weld around the diameter of the freeze plugs so that they can't pop out (not so much that you could not get the freeze plugs out if you ever need to replace them), Then about a 1/8th inch thick layer of "ultracopper" high temperature silicone along the crack path.
This should allow the block to expand as needed in any temperature differential, while keeping the freeze plugs from coming loose if the temperature differential is extreme.
A tube of Alumaseal in the coolant, along with the external repairs, should provide as long a life as a non cracked block. --- Keep in mind that most blocks that do this are never even discovered to have a problem till time for a rebuild, so the effects of the problem are quite minimal.
My opinion anyway. --- Good luck
