van is overheating

I am helping a friend work on his Ford van (straight 6), van is overheating, found the thermostat bad and replaced, with no change. Removed the water pump and when looking at a new pump it looks like no wear, moves freely.Oh yes, the new thermostat is in correctly. Water seems to flow thought the engine and radiator (using a hose) ok. Also,it will plow vapor out the over flow when hot, but indicator does show overheating?

Have any suggestions? Thanks, Joe