Working on a 1992 Chevy Lumina APV. 3.1 L engine
The engine was experiencing several problems which have been repaired....but still running hot (not overheating, just running hotter than normal).
Engine Temperature is 207.3 degrees (OBD1 tester). Electric Fan does cycle on and off. A radiator thermometer shows antifree temperature to be around 210 or so.
But, with the engine running and at 200 plus degrees, the system should be pressurized...but it is not. I can remove the radiator cap without having the coolent spurt all over. And the upper and lower radiator hoses...are hot but can easily be collapsed.
When thermostat opens and water begins to flow I get even heat over the surface of the radiator.
Cooling System Tester showed the cooling system holding 15 pounds pressure steady for over 30 minutes without losing anything. Also no leaks, or signs of leaks. Radiator Cap tested okay using tester but I swapped in a new one anyway. No change
The water pump was replaced about a year ago. Thermostat was replaced (tested before replacement). Radiator is full of coolent. (about a 50% mixture using an antifreeze tester.
Is the system failing to pressurize during operation indicative of a failing water pump??? Water pump is not leaking. No bearing noise (far as i can tell).
Is the troubleshooting technique okay....what am I overlooking ???
Thanks in advance for your help.