[62eyadams]

Today I'm putting coolant into my rebuilt engine for the first time, and after about a gallon I see coolant pouring out of a hole at the back of the block. The hole is in the block, on the passenger side, below the spark plugs, roughly between the 3 and 4 plugs. I think it's 5/16 in diameter, and fine threaded.

I've attached a picture of the hole, with a bolt put in to keep more coolant from leaking out. You can clearly see the oil filter and exhaust manifold in the picture.

So - what should go here? I assume a bolt is wrong, but beyond that I'm a little stumped.