This had stuck thermostat all over it from post #1. Full coolant, higher RPM lowers temp (not the water pump) no leaks, slow coolant movement. Stuck thermostat we have a winner. Sorry guys sometimes it gets a little over Analysi.

 

The local Chevy dealer wanted to replace the water pump and t-stat for $938 plus tax. $20 for the part + $13 for Dex-Cool + $40 for labor = $73 repair.

 

Good deal - ya lucked out. Like you said earlier, do the simple things first. Glad you got it fixed.

 

Is there a way to test the flow of the water pump?