Two things here-

- All 944's and 968's have the bleeder screw where the upper radiator hose joins to the head, and all must be bled if you loose a significant amount of coolant or drain it.
A good way to bleed in a jam is to have a funnel that fits tightly into the resevoir fill, and keep a stand of coolant ABOVE the level of the bleeder screw while you open it. Let the air out and close it when solid fluid comes out. Be carefull about tightening that bolt because I think they're all hollow and can snap if you over tighten.

-Ive seen two radiators recently that didn't cool efficiently, and I noticed that the space between the cooling fins was heavily clogged with sand and dirt. The radiators were replaced so I don't know if a propper cleaning would have cured it, but logically air wouldn't be able to pick up heat if it can't flow through the radiator.

My 87 951 runs in the middle at sub 100 degrees in all conditions stop cruise, 100mph even with the ac on. However at 110 degrees plus I have to stay under 95-100 mph and turn off the ac especially around town. Both fans blow on high speed. Perhaps the radiator may have some deposits, but before trying to find a problem, I'd like to know if others experience similar problems in hot desert conditions. Have I reached the thermal limits of the design?

Diverdan

Its been a while since I've driven mine in extreem temps, but I doubt the thermal limit of our cars is only 110 ambient degrees. I would guess that your radiator is not doing its job, and either it is somewhat clogged with deposits internally or between the fins.

Thanks Gab. The ac condensor is a little battered and while I'm at replacing that, I'll either clean or replace the radiator. It is time for me to just put the car up for the summer as I'll be getting myself to a cooler climate for the next couple of months.

Diverdan