Sounds similar to the issue I had on my Sport Satellite, but it has small block in it . . . . car runs stone cold with AC blowing ICE cold when travelling around town at low speed (below 50mph)- even in 100 F temps. Get on the highway and anything over 60mph, temp gauge goes almost to H . . . .
Took me 5years to figure this out . . . the belt that drives the water pump is also the belt driving the power steering pump. I could NEVER get the belt to stay "tight" - also, had the power steering pump brackets cracking and breaking. Always felt a "vibration" in the steering wheel/column, but no where else in the car . . . . FINALLY a couple weeks ago, I figured it out !!! There was a "Triangular" shaped bracket missing, that bolted to water pump and was support for the front bracket that has adjustment slot on it, that mounts to front of power steering pump. The rear bracket, which has the welded nut on it, that the pivot bolt tightens to, was broken, but in a way that it was keyed together until starting to go over 60mph . . . hence the vibration ! . . . finally got right bracket and replaced the cracked and broken brackets . . . VOILA, TIGHT belt !!! No vibration, and car stays COOL at any highway speed now !!! . . . I have the factory recommended 195 deg stat in the engine.
http://www.hoffmanswinnerscircle.com/images/ps004.jpghttp://www.hoffmanswinnerscircle.com/images/ps004w.jpgThe triangular bracket is the one in the upper left corner . . .
I first thought maybe the lower hose was collapsing, replaced it, no change. I know my rad is good, it is factory original 26" recored with high efficiency core, etc . . . all new components (water pump, stat, clutch fan, etc) . . .
I know my car is small block, but maybe my experience might help point you in the right direction . . . good luck !!
Cheers,
Mark
