4.3L engine not getting hot

Hello: Boy are you lucky Ha. What is not getting hot? No heater output or no temp gauge deflection? If you have a new thermostat and it indeed is working, then without a doubt the engine is getting to operating temp. Now if it is 40 deg below where you live then it might be possible for your engine not to get hot. After engine runs for awhile just feel the radiator hoses and see if they are hot, should be around 150 deg or so. Feel the heater hoses to see if they are hot also. If the hose is cold then there is no heated coolant flowing through them. Explain a little more
Thanks
Good luck
Darryl.

When the water pump and/or the thermostat were replaced a small piece of old gasket material could have flowed thru the system and stuck open the thermostat. And/or just because its new doesn't always meen it's good, allways check a new thermost stat in hot water with a meat thermometer to check operation. Good luck :idea: