Hi Everyone. Jon, I like the suggestion of just driving the car a while. Keep some coolant of your choice with you and check it and top off each time you stop for a few months of driving. You'll get an idea of what the car does and likes. For example speeds below 55 effect my cars differently than above 55 where I see more frequent coolant loss. If she steams, pull over and lift both hood sides.
You might find having the fluid 1 inch above the tubes is too high for what your car wants. One of my cars likes it like that (36 with big top tank, more expansion space), the other one wants the fluid barely above the tubes when cold but the level comes up after getting to temperature (35 with small tank).
The '35 I took on a 2K mile trip from DC area to Indiana and back last summer, and it never boiled over, just got all red gauge for a few minutes when I got stuck in a construction zone in West Virginia near the end of the trip and was stupid and didn't turn it off while waiting to get through. Every construction hold-up the rest of that day I just shut it off and waited.
Idling is not typically moving enough air through the radiator to get an idea of what is going on. My temp will always climb while I'm idling and then come down as soon as I get rolling. These cars usually do not like parades either. They need RPM's to push some water and air to cool it.
I've used Rust-911 as a rad flush in the 35 with a radiator that got removed when I did an engine swap in the spring before the trip, and does a nice job but this is probably not going to be a one-thing-fixes-it kind of project. I even jury rigged something to try to back-flush that radiator with water from the bottom going to the top that didn't help much.
A lot of systems could be and are affecting your cooling.
These blocks are frequently found with obstructions like wire and sand still in the water jackets from manufacture and the only way to get that out is attack it while the block is stripped. The bottom rear of them are a place where we've seen it collect. But you've gotta be fighting the battle for a while to get to that stage!
Thermostats... I run them. But I'd probably leave them out until you get a little further into the troubleshooting. Don't change more than one thing at a time without figuring if that change helped or hurt or made no difference. A close-to-original replacement is made by a fella named Schewman who advertises in the V-8 Times.
Skip Haney refurbed water pumps are a no-brainer to me, you can't go wrong with his experience, service, support, and great products. But even then you're just throwing $250-ish at it and hoping for the best. (If you do send him your pumps, get one of his 3# check valves for the overflow tube, some have found them just the ticket. And send your coil for rebuild and condenser for testing too!) Skip's info is in post #5 of this recent thread:
https://www.fordbarn.com/forum/showthread.php?t=287241
One last thing, Jon, I don't assume any car of this period has original anything especially a bolt-on like water pumps, but even the engine block. Engine exchanges were a thing that Ford dealers did a whole lot of back in the day.
Third Gen Auto has always been a go-to source and has been great to me so buy with confidence from Michael and Jane. They know a about '36's.
Hope some of this helps you to work out your issues. Just know you're a member of a pretty big crowd of old Ford guys working on cooling systems.
