Mr. SwartIkk I follow you and LesMyer and I happened to see this thread in email. My Blazer 2004 does not reach operating temp which is normally 180 or so. Its around 160 or so not enough to warm the heater and will not get warmer unless the ambient air temp is above 75 degrees. I replaced the sensor a year ago but I can't remember the last time changed the cooling thermastat. I did flip the blazer and broke parr of the cooling shroud.

I apologize if I was supposed to start a new thread. But thank you for your time helping idiots like me.

 

Blaz_r, I moved your reply to the other thread into a new thread in the 2nd Gen Tech section for discussion of your problem. There are vast differences in the cooling systems between the s-series trucks and the newer CUVC's.

As to your specific problem, I would say that a cooling system service consisting of new coolant, thermostat replacement, and a heater core flush will likely resolve this problem. It sounds like you might have a stuck open thermostat, but could also be an issue with the heater core flow itself as well. While 160F is low, it should still produce heat inside the truck, just not the same as 205F where the thermostat should regulate.

 

Strange problem, the temp is too low! Could be the thermostat stuck open or it's a high-flow one.
Or, I wonder, if someone put in a high speed water pump and the water is going too fast to pick up all the heat from the engine.