Quote:
Originally Posted by Synchro909
Tghis problem is usually caused by uninformed but well meaning people over the years not knowing that the holes are "blind". Expecting a leak, they put sealant on the threads and screw them in. The next fellow removes the studs, leaving behind a little sealant. This happens a few times and the bottom of the hole is filled with old sealant and the studs cannot be screwed all of the way in so they are forced in. That breaks out the cast iron at the bottom of the hole and creates the very leak the earlier guys were trying to prevent. That's my version of how this thing happens but I'm always ready to hear another
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I gently chase the holes in the block using thread chasing taps, not regular taps. I then check to be sure the holes are thoroughly cleaned (taps, picks, carb cleaner and compressed air on a small nozzle blowing from the bottom of the hole all play a part). Tedious, but worth doing right. Blind holes get copper antisieze only on the studs. I run them in by hand, then just a light bump with pliers to be sure they have seated. Holes that have already been punched out get Permatex #2 on the threads.
I prefer Permatex #2 over RTV for threads. Much easier to clean later. RTV is fine for gasket surfaces where you have a flat surface to scrape.