I just replaced the water pump and all the thermostat parts I finally put it all back together and hooked up the water and started Her. I didnt see any water yet so i waited a minuite to see if the thermo. would open. Well i waited 4 MIN. and shut it off , pulled the tubes between thermo and block not a drop. So Pulled the lower unit today and it was all fried the Impeller was ate up and the housing was partially melted So like i said $100 down the ****ER. I checked the thermo parts they are ok . What is my prob. I cleaned all the passages with compressed air.