Classic/Antique Car Repair: crack, jb weld, oil seeps

Question
I just finished rebuilding a 350 chevy small block. When I installed the three oil plugs behind the flex plate I must have overtighted the top one. I now have a hair line crack in the block. I used a drill to spin the oil pump and a small amount of oil seeps through the crack. Is there a way to fix this with out tearing the engine down and welding it?

Answer
You could try patching the area with JB weld epoxy cement - it's pretty good stuff, but I don't know if it would stand up to the oil pressure.   Before you use it, you have to clean the area very thoroughly to get all the oil and other stuff off the metal so it will stick securely.  I'd clean the area with spray brake cleaner, and blot it with paper towels until the towels come away spotless clean.  Then smear the JB weld around the plug and around the area where you know the crack is - and beyond it.  Wait for double the cure time to be sure.  

Then check it again for leaks before you put the engine back in the car, after the JB weld cures, run the oil pump some more - see if you can get the pressure up to 50 PSI or so (this might take a pretty good drill motor!) - it's good for pre-lubing the engine anyway, and you could see if it still leaks there.   

If it still leaks, it will have to have a small hole drilled beyond the end of the crack (to stop the spread of the crack) and then brazed or welded by a pro.

Good luck - you're going to need it!

Dick