99 B3000 gets hot when idling then it cools off after I accelerate. Ive changed the thermostat, radiator cap, cleaned the MFV, and changed the clutch fan. I'm thinking the water pump. Is there a way to check the water pump other than taking the cap off and looking at the water flow? OR are there other gremlins to check for. HELP PLEASE!!!

 

i had a 93 b2200 and it was doing the same thing

give it gass and look at the lower rad hose and see if it clapses

mine did it after i had it flushed so i put a new one in and every thing was good