So when I first got my Blazer about 2 months ago, it pretty much sat at 210 *Or slightly below regardless of driving in the city, highway or idling.

Recently, my blazer appears to be getting a bit higher at the speeds of 50MPH-70MPH, to the point where the gauge sits between 210 and the next white notch. Anybody have any ideas as far as what may be causing this? I did have my temperature sensor replaced about a month ago.

Thanks for the help!

 

If you're talking about the stock gauges I wouldn't put much mustard on their readings...

Question is what year K5 do you have? 210 is a little high for a TBI motor and way high for an 86 or earlier carb'd model.
You really want to be running at either 180* or 195*.
Trucks made in the last 10 years run at a much hotter temperature, 210*, to improve fuel burn and blablabla... but I'm doubting you're running an LS motor.

 

I ended up replacing the 195F thermostat with a 180 and it completely resolved the issue. It would go slightly above 210 prior, now it never even touches 210 and only sits slightly above the notch prior.

Engine is a 90's TBI