Did you disconnect the battery (for at least 10 min)? May need to reset the computer. Why did you fun flush thru a brand new cooling system? I only use fluch once every 100k miles.

 

I ran it through in case my block had some crap in it... I didn't disconnect the battery but I did accidentally kill the battery so it had been powerless for 3 days about.

 

hi,
a scan tool would give you the temperature recorded by the ECT sensor.
that should be similar to the value of the gage.
more importantly, the ECT value is the one used for engine control functions. The gage readout is just to give us something to look at.
For my truck (2008) both values come from the same sensor. The ECT voltage is read by the ECM (control module) which outputs a filtered voltage to the dashboard gage.
so if the ECM is happy with the ECT then the gage is probably no big deal.
That said, i would keep looking until you figure out what's going on.

you could always just stick a thermometer in the coolant resevoir to get an independant reading.
the sensor is probably not the problem, if you've replaced it twice already.
the wiring to the sensor is not very robust. a bad connector (at either end) or frayed wire could easily skew the answer.
perhaps the new thermostat has a differnt opening temp then the original?
no worries,
-bill

 

It should be a 195 thermostat for my year correct? I'm going to try the computer reset anyways maybe it didn't drain completely. I'll double check the wires right now.

 

195 would be a good guess.
Truth is the thermostat does most of the work controlling engine temps, no matter what the other do-dads are telling you.
So, it should be no surprise that a new thermostat could alter oprerating temps. (Tossing the old one in a pot of hot water would provide some clues to its effectiveness)
And if the coolant system was getting corroded and clogged, all of other items you replaced would lower temps as well.

But, if you believe performance is off, because of your mods., you should confirm that the ECT is reporting the desired (correct) temps. Matching the number on the dash gage is nice, but not really critical.
There are certainly lots of reasons for poor fuel economy.
But there shouldn't be much grey area about what the temperature is.
Convince yourself its hitting the right number so you can go from there.
-bill

 

I know that the temp on the actual engine is correct because when I shoot it with the gun it is around 198-205 and my fuel economy didn't suffer until this started happening... There has got to be something somewhere that is messed up either the ECM ECU what ever you call it on a Chevy or the wiring or something. I'll be digging into it after the Thanksgiving dinner tomorrow so I'll let you guys know if I can get it fixed. I also noticed when I was looking at the wires I frayed one on purpose to see if the engine light would come on and it did. Man this is really starting to bug me

 

that all sounds good.
my point is...
now that you are confident that the engine temperature is correct,
you should determine that the control module(ECM) also thinks the temperature is correct.
many scan tools will provide performance data ,real time, without the need to trip any error codes. The ECT (eingine coolant temp) is the magic value used for control logic functions. Odds are that your dash gage temp is the same as the ECT temp.
But i think you should first get a reading from the ECT, BEFORE you fix it,or you will just be 'grasping at straws'.
There are way too many reasons for poor fuel economy on a 15 year old truck.
give the vehicle a chance to tell you what's off or be prepared to change everything.
happy thanksgiving.
-bill

 

So I figured it out... When I put the new sensor in it never really got tight so I just kept turning and turning until it finally just stopped suddenly... Well it had impacted the thermostat itself it was in so deep. Put some sealant around the threads and only put it in about half the distance and everything seems to be perfect except now I'm having a hell of a time getting my system to "burp" any tips on that?

 

good, ...i think.
I'm a bit confused.
is the sensor and thermostat close enough to interfere with each other?
never mind i just checked for myself

I believe you can damage the sensor by over tightening.
installation is only 10 ft-lbs
have you checked the sensor resistance since reinstalling it?
what happened to the first two sensors?
can you compare their resistance to the current one?
what does the thermostat look like after all this?

so far as burping the system goes....
i would park on a slope that allows the fill cap to be the highest part of the coolant system.
open the cap (w/o getting scalded)
let the system warm up
turn on the heater
run at fast idle to move water
repeatedly squeeze the top radiator hose with both hands to dislodge any air bubbles
add coolant as needed.
i've seen similar suggestions in past threads that may provide a few more tips.

But ALLDATA says this is all you need to do:
These engines do not require a specified bleed procedure. After filling cooling system, run engine to operating temperature with radiator/pressure cap off. Air will then be automatically bled through cap opening.

...big help, huh?

-bill