3800 S2 NA - Water Leak Behind P/S Pump

[tweak1029]

I am finishing up an engine swap from a 99 Buick Park Avenue to a 99 Olds Intrigue (3.8, not 3.5). One of the holes in the block leaks water on the Park Avenue engine.

 

Here you see the hole that is unused on the intrigue block. The bolt impression is from me screwing a bolt in to find the right thread size to make my own plug - it was unused and unleaky.

 

 

Circled is the corresponding hole on the park avenue block - obviously a smaller hole. This one leaks water as quickly as I put it in. I've confirmed with a video (dangling phone in while adding water).

 

My question is, has anybody seen this on another engine, and do you know the proper thread size so I can fashion a plug for this hole? I have tried a m8x1.0 (I think, the typical 10mm bolt thread size/pitch) and it still feels too large for the threads. The park avenue was not leaking coolant when I pulled the engine, but I don't recall removing a bolt from that location.

 

This is very frustrating. The swap is complete with the exception of adding coolant.

 

EDIT: I have some taps, but it's too tight for a t-handle without removing the engine again. Also, does anybody know the fluid capacity of the torque converter?

 

EDIT: I wound up digging through my bolts until I found a long one that fit, then dug around more until I found a short one. Turns out it's only slightly smaller than the P/S pump mounting bolts. I think the tapped portion of the hole is very shallow and I felt it bottoming out rather than not fitting. I hope this helps anybody haivng a similar issue (though a google search prior to this post only yielded a couple of instances).

[Imp558]

on an H body car that would be a hole for an engine mount. I just went through that the other day changing belts and an idler.