I have not replaced the Cap. Curious why that would cause an issue?
I'm hoping it could be that or a bubble instead of a head gasket or something major.

 

It is supposed to release in both directions at 15psl. If it doesn't then count cannot go back and forth. Also 15psi raises the boiling temp by a co sidereal amount. Also a tiny leak in the seal may be undetectable.

 

Update:

Took the car for a short drive about 15 mins.

Temp gauge working. Fluctuated anywhere from 174-181. Even had it on the freeway at 80mph for a bit.

A/c worked great. Cold air.

No overheating issues.

any ideas or leave it alone? Lol

 

Drive it check it in a few days!

 

Less than 180F will cause a code soon.

 

That's why I came on here askin in the first place....the car has never given a code?! No CEL, nothin. I'm confused lol.

 

Drive it if code shows up post it in full we'll be here.

 

Will do.

 

BUT, the temp display goes --- and the A/C doesn't work. That means there is a code "pending".

Somebody out there is selling mis marked T-stats! If your temp is running 170F-181F, that means you have a 170F T-stat. The running temp should be right around 180F-195F on the highway. Never below 180F.

You are not the first!

 

That's one reason I recommend only using GM AC Delco T-Stats, they others can open to soon and cause this problem! The 180 degrees is what the ECM is looking for and to be at by a set time or the MIL lights up!
And the coolant it likes is Dexcool, never overheated Dexcool, not over the expiry date of 5 years Dexcool !