My gut tells me the little paper gasket is not doing its job. I have made my own gaskets out of gasketmaker in the past, but what is your preferred method? Gaskaseal?  Trace and use a better gasket? I scraped all of the old gasket off and have very clean surfaces on both sides.   https://drive.google.com/file/d/1qPz8NSo3ldpsIruP2JRoRjScz4but56E/view?usp=sharing" rel="nofollow - https://drive.google.com/file/d/1qPz8NSo3ldpsIruP2JRoRjScz4but56E/view?usp=sharing

Last year I just dealt with the leak (it was smaller last year), and as you can see, it is right at the paper gasket. But really, the o-ring seemed like it was the right overall diameter (2" ish), but tiny and not very thick (*but was identical to the o-ring I pulled out)

This is what I replaced https://www.nautiqueparts.com/product/impeller-pcm-gm-for-non-serpentine-belt-engines-rp061017/ and impellers were the exact same size (same purchase as last year). 

Thoughts?  Thanks in advance! 

This is a 1994 SN w/ Ford engine. I have no overheating issues, just doing routine maintenance :)

My gut tells me that you've linked the wrong impeller or you have some mighty strong fingers to squeeze that  RP061017 impeller into your pump. And stronger arms to make the pump halves bolt together. 

The PCM number for your pump is R061015  (Or Sherwood 9959K)

Assuming you linked the wrong impeller, I'm thinking you should make sure both surfaces are flat with some lapping compound or sandpaper on a flat plate and then use a little Permatex2 or some equivalent type non hardening sealer on both sides of the gasket.

To check both sides you need a plate that has a hole in the middle for the shaft to stick thru while lapping.

Well that's a relief 

Just check those surfaces flat and a little sealer should do it

As far as I can remember all mine (85, 95, 2000) just has a brass backing plate and the O-ring and they never leaked 🤔

Click on the link for a Sherwood Catalog, go to page 32 

http://www.go2marine.com/Product-Guides/MFR/Sherwood/Sherwood_Catalog_ENGLISH.pdf" rel="nofollow - link

I guess mine is on there and I just never noticed it 🤔

It only needed the O ring and no paper gasket.

The paper gasket showed up with the bigger wear plate that wasn't set into a recess.

Here's a picture of the G20 plate recessed into the bearing housing on a pump from 1976

And a picture of couple of the later style next to the old style