Hey guys, so I was trying to prime my engine using a oil prime tool I had made. Long story short, I have a tapped hole and I do not know what goes there. The hole is located on the rear lip of the block, it sits just off the intake manifold. It is tapped to a 3/8-24 (very odd) size, I know it's part of the oil passage because I primed oil all over my wrist... So, if the oil pressure gauge sensor goes by the oil filter what goes up here? Is it a sensor for a dummy light? Do I just plug it?

Thanks

In some vehicles that's where the gauge sending unit goes.

It's not 3/8"-24; it's tapered pipe thread. 1/8" NPT to be specific. If your car doesn't use it, just plug it. You can get brass plugs in that size at the hardware store.

Yes a geyser of oil will shoot out if you don't, and start the motor. I've personally witnessed it. Quite a mess.

Thank you for the info... I can only imagine the geyser as the spurt shot pretty high just turning it by hand...