Ok, i’m confused. The engine was cold when it went in the river. We you rolling with a dead engine?
First issues first. Have you flushed the engine out to the point you have no water at all? Water will stay in the engine for many oil changes and corrode the bearings. I use a half engine oil half ATF mix as a flushing oil. the ATF has a very high detergent content and will hold the water in suspension more than engine oil so you can drain it out. Don’t leave it in there for a ride, just 15 minutes, a quick lap around the block and dump it again. Keep washing out the oil filter, no sense in using a new filter every time.
The water pump has a leaking inner seal. You are replacing the outer seal only i’m guessing. The weep hole issue is the cavity between the inner and outer seals. the hole is there to show if you have a leaking waterpump seal. The outer seal is to stop water escaping from the cooling system. the inner seal keeps the engine oil and coolant from mixing. The weep hole sits in the dry cavity between them.
Seeing as it sounds like BOTH seals are leaking i’d have a good look at the shaft and bearings, a partly collapsed bearing could be causing the seals to leak. In theory best practice is always replace the shaft but we cheat a bit on that one when we can. HOPEFULLY the bearings are not worn from moisture in the oil as i’d be sweating about main bearings next.
Lastly, how does the engine sound? Noisy in a grumbling bearing kind of way? Did you hydraulic lock it? was it running hard when it hit the water or just idling? When you towed it was the rear wheel ever locked and you seat bounced it past?
If you have hydraulic locked the engine then forced it over top dead center it needs a new connecting rod. I weeny bit of a bent rod will break at 8000 rpm and become a metal cutting saw the consumes your barrel/head/cases/.gearbox. I’ve seen it first hand. Not nice.
