Nagging oil leak (a stumper for ya!)

[KShortell]

OK, it's my turn for a stumper.

I've got this nagging oil leak that I'm having trouble nailing down, but I do have it localized. This is on my stock 1986 350 SBC (LS9) engine.

Keep in mind that the valve stem seals, valve cover gaskets, oil pan gasket, rear main oil seal, oil cooler hoses, and oil filter are all new. The valve covers and rear main are not leaking at all.

Only the driver's side of the block below the manifold alongside the rearmost two cylinders is wet. I'm almost wondering if the factory oil cooler connection/adapter at the spin-on filter location has a bad gasket. It's never been apart.

It's a nagging leak, but not a hemorrhage.

There is a bolt between the middle two cylinders one either side of the block just above where the oil pan is. I'm not sure what these are. The oil starts from here back on the driver's side. I'm inclined to think that these bolts are coolant drains for the jacket in the block. My FSM and Haynes book don't show these bolts.

See the photo below for the area in question and a close-up of the bolt I'm talking about. Thanks!




Kevin