So I got my 86 4runner back from the grave. Sitting since 06. Pulled the tank and clean gas. Had the injectors cleaned, repaired stripped number 1&2 sprk plug thread hole with inserts (the plan is to replace the head once it's running and passed smog. Maybe a header)
she ran smooth! Idles great and and I drove her about 10 miles round trip,, got home pulled the radiator cap and calm, no boiling over. And needle stayed below 4 o'clock. I had drove it to the muffler shop, but they were too busy.
next day I replace the exhaust manifold gasket and a couple bad studs and flange gaskets.
I then drive it a mile to the smog place and it's hot, I can smell it. i bring it right home and it was boiling and now it won't idle.
oil and coolant look normal. Today I'll drain the oil and coolant, see if I see any milk, but it looks fine on the dipstick. I'll check out the thermostat. It sat for so long.

 

Silly question: Are your belts all still there and does the water pump and fan spin when it idles?

 

Yeah, sounds like the belt for the water pump is missing, or slipping, or that the water pump may have a problem. The fan clutch is also a very real possibility. Was the fan making the characteristic "whooshing" noise when the truck got hot? If not, fan clutch.
You can feel, when the truck is warmed up, whether the water is flowing properly, IE the water pump and it's belt are ok. Just feel the driver side of the top of the radiator, or the lower radiator hose. If it stays very cool, there's no water flowing, so either the water pump has gone south, or the system is clogged completely someplace. Most likely the thermostat not opening, or not opening completely.
Did you say you had taken the thermostat and tested it in a pot of water on the stove? Either that, or just replace it. They're very inexpensive, even for an OEM item.
Did you ensure there was the correct amount of fluid in the recovery tank? It's important.

The cooling system may need a good flushing out. Did you look down inside the radiator to see if the downtubes you can see were clear and open? Did you give the outside of the radiator a good cleaning, using either air, or water, to backflush the fins? Critters love to build nests in the strangest places! Like inside the radiator shroud. Speaking of, is the radiator shroud completely installed, including the little piece that goes across the bottom? It matters a lot.
Don't forget, it could be as simple as needing the cooling system to be burped. They can get air bubbles stuck in the strangest places, and they can cause very real problems.

Did you look on the inside of the oil filler cap for the "chocolate milkshake"? That's the most likely place to see the problem, not the dipstick. By the time it gets visible on the dipstick, it's a BIG problem. Another place is the radiator cap, but you said you looked there. Was the radiator full before it overheated? It should have filled up the recovery tank when it boiled over...

Just throwing out as many possibilities as I can think of. I wish you the best of luck. Keep us up to date on how it goes for you!
Pat☺

 

I checked the old thermostat and it was closed at 200. Boughton a new one and confirmed it opens at 185.
I bought an autometer temp gauge. I've installed in in the top radiator hose using an adaptor. I drained the coolant and ran water through the empty thermostat opening and out the cock valve.
the belts are there but I'll conrm no slipping.
the radiator is going to be replaced,I'm looking at a 2 row aluminum.
I have one of those peak flush kits I was going to try, then fill and start.
Thank you very much to both of you for helping.