A follow up and (hopefully) the last chapter of this particular project.
After a few runs on the muffs it became obvious that, although I had a cooling water flow, it just wasn't like it was before the old impeller went. The flow through the tell-tale at idle was just a drip (again, on the muffs). Running on the muffs I had to crank the faucet way further open than I had previously.
I had forced water through every available orifice before putting the LU on, so, I was sure the issue wasn't a clog in the cooling passages. So, I pulled the LU and disassembled the water pump for further study. I had the old parts so I compared them to the new (Sierra) parts. Except for the previously mentioned bottom plate, they were identical. Whoops, wait a minute. There was the new gasket that goes between the housing and bottom plate - sitting there kind of mangled. Took a closer look, compared with the old gasket (fortunately kept it) and, damn, it was half the thickness. Took a closer look and the new (third party) gasket wouldn't even compress when the pump housing was placed on the bottom plate.
Went to my local O'Reilley's and bought some water pump gasket material - turned out to be a hair thicker than the original gasket material. Cut new gasket, reassembled, test run this p.m., and, yessssss, back to the way it was way back.
The damn gasket made the difference. Who'd a thunk?
So, I again learned a few things by experience. First, 3'd party parts are great - save some $$$ and also deal with that dreaded "NLA" on the OEM parts list. But, as much as possible, check
every piece against the old pieces.
Second. Save old parts till you are sure everything is working properly.
Only thing I'm worried about now is that the O'Reilly's gasket material didn't say "marine" on it. Hope it holds up
