You get adequate air coming through the radiator at something like 20mph, so the fans running or not sounds like its not the real problem.

But the fans are switched by another temperature switch. I'm beginning to wonder whether your coolant is circulating properly. That gets into more scary territory like a clogged radiator or a waterpump somehow not being right. I've heard (not personal experience) about waterpump impellers coming loose from the shaft, or the vanes become mostly corroded away.

Do you have something like an IR temperature gun? Or simply feel the upper radiator hose. I haven't owned a V-6 so these are generalizations... The cylinder heads get hot first, then the hot water has to make it to the thermostat. On a 4-cyl you have the pipe across the back of the engine to carry water from the T-stat to the waterpump but I don't know if there's anyplace on the V-6 where you can verify the hot water is circulating out to the T-stat & pump.

Maybe some V-6 owners have better ideas?

 

I do have an ir temp gun. The v6 has a water tube that runs from the top passenger side across the top of the motor to the driver's side to the thermostat. The water pump was installed brand new when I rebuilt the top end and put a new timing belt on less than 500 miles ago.

 

New water pump

Thermo housing with pipe

How it lays across the v6

 

I guess one thing I could do is pull the thermo out put the housing back on and force flush entire system or use a shop vac and pull water through the system???

 

Did you try removing the thermo and taking it for a drive to see if it overheats that will at least see if it circulating or not.

 

Negative. I was going to, but got a hold of someone while on the side of the road and had them bring my old thermo to me to put in on road side. It started raining on me and has been and will still today. Lovely north texas spring weather. Will be able to do something tomorrow on it. Inspection runs out this month, was on my way to get it inspected lol

 

I see that pipe is buried under the intake manifold so you can't measure temperature when the engine is running.

- Looks like it's not possible to install the waterpump incorrectly.
- Presumably you looked whether that pipe is blocked with crud. (T-stat housing too)
- You've been around long enough to know which way around the T-stat is installed.
- I'm running out of ideas.

Drive without the T-stat sounds good. Check whether the bottom of the radiator gets hot. The top might get hot even if it's not circulating, but the hot water won't be forced to the bottom.

 

Should I leave rubber gasket in thermo housing while running without thermostat?

and yeah I cleaned every pipe, hose, fitting, nut, bolt, etc when I tore this sucker apart and redid the top end and put the timing belt and stuff on it.

drove about 500 miles after rebuild.. never overheated.
replaced power steering hose
replaced number 1 fuel injector
replaced upper radiator hose
replaced fast idle thermo valve ( with a 4 cylinder 1 because they were the same )
replaced some misc hoses
replaced fan thermo switch
flushed heater core
flushed system

would a fast idle thermo valve have any influence on overheating?

 

Got both thermostats in the house and did the boiling water test. They both opened. I jumped the plug on the fan temp switch on the thermo housing with key on and fans didn't come on. I thought they did before.. hating this car

 

Are both of your fans still wired to the condenser fan relay?

When the engine is cold and you open the radiator cap, how much coolant (if any) do you need to add?