My dakota is running warmer than i think it should be....

Its a 91 LA 318. I have a 180 t-stat in, and have done the taurus fan swap with 2 speed controller (turns on at 195 and 210)

Its been fine until today when it warmed up to about 70 degrees outside. Thermostat is newer (did it when i did fan swap a month or so back) its not over heating so to say but its steadily climbing going down the highway to the point my fan kicks on and will still climb.
It hit almost 220 today on my way home. Ive always been told that your fan wont/shouldnt run while traveling at highway speeds (60-70mph) Im not finding any leaks, nor am i losing coolant. Ive tried to burp it again and had no change. I also took the garden hose today and cleaned off the radiator fans. Going to try and flush the rad tomorrow see if that helps and maybe do a whole system flush (depends how much coolant i have handy still) Im wondering if it might be caused by my water pump getting weak.

just looking for more insight pointers, maybe im over looking a test/process to check. Any recommendations for cleaners to use for the flush? anything to stay away from?


Now a possibility that may not be related to the coolant system. On my drivers side exhaust manifold there is a little round thing (butterfly heat valve im assuming) there is a spring and it only moves so far if i turn it by hand, but it doesnt seem to change between hot or cold. If it is what i think it is shouldnt it spin one way or the other when its cold and then release when the truck gets warmed up to help with initial warm up (when its colder out anyway) which way if anyone knows is open or closed mine is always rotated the farthest counter clockwise... (you can only rotate it clockwise and then when you let go it springs back counter clockwise until the stopper if looking from the front of the truck)

 

The little butterfly thingy is called a heat riser--it directs exhaust up and through the intake manifold to help warm up the carburetor and engine. It isn't the culprit. You may be able to loosen it up with blasts of PB Blaster or some other penetrating oil. Very old school, it's not used on Magnum engines. (But you've got an LA engine.)

A 91, so if it's got the original radiator, it's pushing 25 years old. Likely home flushing won't help much. A new radiator is probably the best solution. And while some say they haven't had luck with the ones on Ebay, I haven't had any problems. Get a two row replacement, btw.

 

All i can find for replacement radiators ate the plastic/aluminum ones. Im wanting a brass/copper 2 row replacement (what i have now) anyone have any luck finding one for the pre-magnum motors.. (only difference i believe is the upper hose is on passenger side for mine and drivers side on magnums) I think im gonna just do a complete change.. new thermostat new heater core and radiator hoses new water pump new radiator and do a dang good flush at home before changing all this. As hard as i can be on my truck a completely refreshed cooling system definitely wouldnt hurt.

i just would rather have a brass/copper radiator over the plastic aluminum ones...