A backyard landscaping project has stolen a lot of my spare time since this problem developed, but I can finally make an update.

Virtually anything that could have gone wrong went wrong.

- The temp sensor is the wrong one (two wire vs my one wire).
- The very expensive custom brass rig I built to go in place of the auto temp sensor keeps the sensor just enough out of the flow that I don't get an accurate reading and I need to splice the upper rad hose. Otherwise, it looks like the coolant is 100* at operating temp rendering the gauge effectively worthless.
- The copper splitter I bought technically does install just fine but I can't attach anything to it. It needs extensions or 45s or both or something. So I just installed the new oil PSI sensor, which thankfully is the correct one, back into the port. I would have installed the gauge instead, but the sender won't fit in that space without help.

All that mess said, I idled the car for at least 15 minutes, it definitely came up to temp, and there was no RCELOD.
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75,000 mile 1989 Crown Vic LTD wagon, answers to "Marge".