I reinstalled the temp probe using the flimsy looking aluminum crush ring that came with it and used a copious amount of indian head sealer (instead of teflon) and she sealed right up after a day to cure.

I threw the coolant back in that I had siphoned out to redo the temp probe and took it for a drive. It was 90°+ and I ran up the steepest hill in the area. The new temp gauge ran between 205° and 212° the entire time regardless of driving style and use of ac switch. The stock gauge on the other hand ran between "o and the top of the m". Using th ac switch would immediately swing the gauge a full letter hotter (and would increase the engine pressure gauge a small amount).

I suspect that the instrument cluster regulator has been the culprit the whole time but my water pump fins were getting a bit gnarly and showed signs that the gasket might give out soon, and who knows how old the clutch was. I removed the alternator while in there and had it bench tested (motorcraft brand, 95 amp, and still good). I also replaced some old looking hoses and found some bad vacuum lines in the process. Was the radiator toast? Maye not, but there appeared to be half blockage so I'm really not remorsefull for replacing all this stuff.

Thanks to everyone's help on here, I feel MUCH better about hitting the road again. I just need to track down the gauge issue.

So there was old green radiator fluid in the block which is now mixed with my clear radiator fluid sold by advanced auto parts. Do I need to drain everything (including the engine block this time) or are the fluids okay to mix?

I also should probably ask... When removing the radiator, I realized a very small amount of transmission fluid is lost. Only 1/2 a cup or so dribbled out of the lines.. Should I top it off, drain and replace the fluid, or go get a flush with the new radiator installed? I didn't see this mentioned in any of the other forums I read through during this process.

 

From the temperature gauge it sounds like you are running at a good temperature. My 460 runs at 199F.
When I replaced my radiator, only a tiny tiny amount dribbled out. Not enough to worry about. I would check with the dipstick, and if it's fine I'd just drive it. I suppose since the fluid now has to fill the cooler lines in the new radiator you might be a little low on fluid - I did not even check mine so now I will. I don't see any reason to drain or replace or flush the transmission fluid.

I didn't know about clear radiator fluid so I would read the bottle to see if it says it is compatible with old fluid. I would think it would have to be. There is no way you can get all of the old coolant out of the entire system anyway.

Steve

 

After all of this work in 100° and the lost weekeends, reading the bottle for compatibility sounds amazing! Good call.

I call that a stupid check, and well, it would be stupid not to do that. Here's hoping!!!