Hot at high RPM

bytor from a car i had a long time ago check this. had a 72 caddy with a 472 in it and would do the same with upper hose. what it turned out to be was the overflow tube going to the tank was bad. it would cllapse on the inside. i replaced the hose and upper hose did not collapse anymore. also i think they even make hoses with springs in the upper.

Didn't have a chance to chance the reservoir hose today.  I assume a collapsed reservoir hose acts like a bad radiator cap.  It could prevent the coolant flow to and from the reservoir.  I don't understand how that can cause the upper radiator hose to collapse.  I'm no cooling system expert though either. :)   By the way, nice forum.. I'm a 1st. time vette owner and this site is a good resource for information.

i am far from one either bytor but had the experience with the caddy of upper hose collapsing and could not figure it out. a top notch mechanic i knew told me that might be the problem and as i had nothing to lose except a few bucks for the hose and time it took to do it as on that car had to remove top covering the radiator up to the grill. it cured the problem. i would think not having a way to vent itself on a closed system had something to do with it. eddie208752007-01-27 16:04:58

Eddie is probably right on this...if the hose for the puke tank(overflow) is collapsing, then it wouldn't be able to "suck" the coolant back into the engine as it is needed. Check to make sure there is no restriction on either end on the hose first, and that the fitting that it fits onto on the tank is clear.
That's why the upper hose collapses. Then, as the upper hose collapses, you have an overheat condition due to the restriction.
I think if ya'll will take the time to study any of your cars, you'll see this action take place a lot, mostly on initial start/warm-up. As the engine warms to the opening temp for the t-stat, the upper hose will collapse for a few seconds, while it pulls the coolant back from the puke tank. This isn't a problem tho, because it only happens for a few seconds. If the hose is staying collapsed while driving....that's a problem!
Replace that overflow hose, and make sure your rad. cap is the correct rating(13-16 lbs) for the car.

Yep, had trash in the reservoir clogging the line.  Pulled the tank, cleaned it and installed a new reservoir line.  I went ahead and replace the upper radiator hose and cap (16lb).  I was able to drive the car at 3000 RPM with out over heating.  However, when I came to a stop it went up to 220 or so but then dropped back to 180 while driving.  Is this normal?  Thanks for your help with this..

only thing i could think of is maybe a lower pressure radiator cap. if pressure is too high it can't release it and water will heat up more before opening the cap.

What yould you recomend?  13LB?

I'd go 13lbs...but check the service manual, or owner's manual...