Hole in engine block under valve cover.
I'm getting back into doing some work on my 86 cj7 (inline 6) that I've been away from for some time now. Well among other things, I've decided to replace the valve cover and gasket. After removing valve cover I noticed there is a threaded hole through the engine block and I can see coolant pooling. This hole is fwd the block on the driver side under the gasket. Is the a problem? I have noticed some compression issues but haven't put much thought or time into this. If this hole is a problem, can it be plugged and if so what would be some plug options. Thanks for the help.