[SteveJones]

I've got a 2000 Silverado extended cab 4x4 with a 5.3L V8 with just under ¼ million miles on it. Over the past three years; I've replaced the water pump, the radiator, and the thermostat. I just had all the hard brake lines replaced. The heat core was bad, so I had the guy replace it for me while he had the truck.
It runs fine, but the engine seems to be running cold now. In the past, it sat around 210°, but now the temperature never seems to get above 175°-185°. The heater puts out decent heat, but it's not what I would call hot. Any suggestions?

 

[Tatsngats]

Maybe your temp gauge is going bad? Maybe you put in a lower temp thermostat? Just thinkin.....

 

[rollover]

Did you replace the water pump, radiator, thermostat and heater core all at the same time? If not at what point did you notice the temperature difference during the replacement sequence? As previously stated the thermostat would be a likely culprit. Or the engine temp. sensor/sender unit or the temp gage going bad. My 99 Silverado has run at 195 degrees indicated since day one. Even after a couple of thermostat replacements. I would say if the engine runs good where it is at, not engine codes being generated and you are getting all the cabin heat you need, run with it. If it continues to degrade I would suspect indication problems.