Hello All,
a crack in a block can be devastating, but it doesn't necessarily mean its scrap. If the block is being magnafluxed it should show other cracks. Depending on the length, I don't think it should be scrap. These blocks are only going to deal with a maximum of 7lbs water pressure during operation and that really is nothing. If you are running a zero pound radiator cap it will literally be nothing. I've seen blocks that were grooved and drilled at the crack ends (to stop further propagation) and then heated to 400 degrees in a furnace, and then arc welded with a high nickel content rod. I've also seen people heli-arc them with stainless steel filling rod, brazing with brass as mentioned above, and even using cold jb weld.
Yes, to all those skeptics, cold weld does work. I still see that engine every month or so and it has been running beautifully for about 10 years since its rebuild.
Now if this were on the compression side of an engine the crack would be seeing 150-175 lbs of pressure and there I wouldn't recommend cold weld. But for seeling an external water jacket near a freeze plug opening I've seen it done.
The last option is drilling out a series of holes along the crack and filling with a series of overlaping pipe plugs. I've seen that done on heads before, but I actually think that the above methods are easier.
Just a word of caution, if you plan on heating the block up for repairs, do it before any maching is done on the block. You dont want to warp a freshly decked, bored, and aligned bored block. It will not be straight afterward, especially if it is not cooled very slowly after working. Do not quench the block at all to try and cool it, it will warp and possibly crack in other places, defeating the purpose of fixing it.
That being said, it really does depend on the length of crack and access to repair. If no other cracks show, I certainly would try and repair it.
Just my 2 cents.
54Monster
