Thermostat not opening

completed timing belt change, new waterpump etc. truck starts up and runs great. I am not getting the thermostat to open is my guess. I put a new one in and when that did not work , put the old one back, same issue. bottom radiator hose stays cold, truck temp rises and not hot air through the heater. any suggestions would be great

 

Sounds like you’ve still got air in the system. Have you turned the heater on in the truck while the engine is running to try to burp out any air with your radiator cap off? Also squeezing the upper and lower radiator hoses.

 

Throw the thermostat in some boiling water and check if it opens..

 

I suspect it has something to do with the pump. Is there a possibility you routed the belt wrong and it's turning the pump backwards???

 

figured it out, air in system needed purging

 

thanks for all the responses.