03, 3.8L... change radiator, thermostat, water hoses, fan assembly... fans or kicking on.. but I can't figure out why my temperature is going all the way up to the halfway mark.. and goes a lil past it... then comes back down to halfway... b4 I change this my temp only use to go up like 3 r 4 lines and stay in that area

 

Beehooved,
The issue that you explained sounds like a little air pocket is still in the coolant system. Keep in mind that the normal operating temp of the GM 3800 is 210 degrees F. You could Try to bleed your coolant system again to ensure all of the air is out. If it is still running on the hot side you could try testing your thermostat by dropping it in water on the stove. when the thermostat opens record the temp of the water. Should open @ 210 ish.

 

ok will try that.

 

Thats the standard operating temp for the 6th gens. Just had mine rebuild a few months ago. Does the same thing yours is, just gotta check the coolant. 😄

 

I noted that I did all of the same (except fans) several years ago and mine runs higher than before - I used an Auto Zone radiator and I think it's just not as efficient as the OEM. The air pocket/bleed is also a possibility for your issue.

 

yes.. this is what I determined after I changed the T stat to a 180... plus I got my radiator from rock auto... so I guess that made a big difference in my before normal temp operating range... I did bleed it out and change T stat and its holding steady by the halfway mark on the temp guage...