I recently changed the water pump and thermostat in my 2000 dodge ram 1500 5.9 l. Since then the heater is luke warm, the top hose is hot and the bottom hose out of the radiator is very cold. Is there a way to purge the cooling system, what are the side effects that these symptoms can cause in the long run to my engine. My first guess is that the thermostat is bad out of the box, it's from napa, I believe I installed it properly, does anyone have a diagram? Help me ...I beg of you.

 

If the top hose is hot, the thermostat is opening. Here's a thread on purging the air out of the system: https://dodgeforum.com/forum/2nd-gen...in-system.html