Maybe the water pump truly is the last resort. I can't imaging that, however, as the failure mode for a water pump tends to be bearings seizing or bearing seal leaks - not impeller failure.

Is there a cooling system bleeding procedure for your car? Perhaps you have air trapped in the system? I seem to remember that thes enegines are auto-compensting, but I could be wrong.

Best of luck. You could always just wait for cooler weather to solve your problem too.

Troy
1995 E420
83k