I have an interesting issue. If you're looking at the water pump housing on the passenger side of the engine, there are 2 mounting bolts, and in between those 2 bolts, recessed in a little, is another hole for another bolt. I missed this when assembling the engine, and now its leaking coolant when trying to fill the system. I can't for the life of me remember taking a bolt out of that hole, and I don't have a bolt that seems to fit. I have tried 5/16 of various lengths and it just slops around in the hole. 3/8 seems to be too big. Any ideas?

Any help appreciated, thanks!

--Paul

It is 3/8". Run a tap in there if you have to.

Big block housings have 6 bolts--3 on each side.

They are all the same thread size.

These holes go into the water jacket, so you will never seal it without the bolt in there...

Right, each side of the housing has its 3 mounting bolts, but there is another hole between the 2 top mounting bolts on the passenger side of the engine. See picture.

That hole is where the water temp sensor screws in.

Then a wire attaches to make your temp guage work

put a temp sensor in there or a 1/8" (I think)pipe thread plug

Gotcha, I put the temp sensor in the top, right next to the one heater hose nipple, didn't even notice that hole there until it started spewing coolant. So the 1/8 pipe plug it shall be

Thanks!

There's still 3 bolts on that side of pump housing, so if you only installed two, you are still one short.

I know, all 6 of my water pump housing bolts are installed, and not leaking. I missed the hole for the sensor because I had installed it with one of the holes on top of the housing. I got the hole tapped, and plugged with an 1/8 pipe plug.

Thanks for the help guys!

--Paul