Engine overheats at idle and while driving. I have replaced tstat, water pump, and fan clutch. No leaks and no milky oil.did my best to burp system when I replaced coolant. But engine is still getting way too hot. I noticed my upper hose reaching temps around 150-160 degrees while my lower hose was a cool 95 degrees. Radiator is free of any debri and it's only 80 degrees ambient temp. So please help. I would be very grateful thanks

 

maybe just a bad gauge? Upper hose temp sounds fine

 

I used an infrared thermometer. I thought it was odd the two hose had such a large difference in temp tho

 

Looks like your radiator is working good.
I'd say that your gauge is off, might try a new temp sensor.

Do another check, get it high temp by what the gauge says,
and check the temp on the hose real close to the TStat housing.

PS:
Got a Lazar Gauge too, love it !

 

All my gauges in the cab are broken (need new stepper motors)... that's next on my list. But temp at the tstat housing read around 95 while the block itself is 250+... Is it possible the coolant passages inside the block are clogged up? Thank you for helping

 

Anything's possible, but...
Given that you've replaced the Coolant, I'd strongly suspect that you have air in the System. Did you pull a Vacuum on the system when you replaced the Coolant ?

 

No I did not. When I refilled with coolant I just parked at an incline, let the engine idle, left the cap off, and filled while squeezing the upper and lower hoses. So should I try again and use vacuum? How would I fill and vacuum at the same time?

 

Tanin Auto Electronix here. We are vendors on the site and can help you out with new stepper motors for your 05 Trailblazer! Here is the link to the X27.168 Switec Juken Stepper Motors:

GM Switec X27.168 Stepper Motor

If you want to send in the cluster to have us go over it, we are happy to assist with that as well. Just give us a call or shoot us an email with any questions.

Thanks,

 

We appreciate our valued Sponsor contributing to this thread.

You'd probably need to go by a Radiator Shop, and have them use their Pump to clear the air out of your system.
You could do it yourself, but, the cost of the equipment for a one time use may be prohibitive.

https://www.youtube.com/results?sear...ant+vacuum+kit+
and
https://www.amazon.com/s/ref=nb_sb_n...nt+vacuum+pump

 

I had the same thing happen to my 05 Trailblazer back when I had it. Turned out to be a bad cooling fan relay. Replaced it with a new one and it stopped overheating.