Brundle

Yesterday as I was driving home on the highway I noticed my temp gauge was staying up at 3/4 high. (approx 115 Celcius).
Once I turned down my music I could faintly hear the fans constantly running on high. But car was not overheating. Just running close to the overheating point.
When I got off the highway and shut it off the fans ran on high for another few minutes cooling off the engine. Once the fans shut off, and there was no more cooling the coolant was boiling in the rad (could hear and feel it with hand on rad cap).
I think it was hissing a touch from the rad cap area. Was hard to tell with traffic noise.

Anyhow, just wondering if you guys have any suggestions? I'm thinking loss of pressure due to faulty rad cap. Either that or thermostat is stuck closed. However, I'm not sure if the car would stay out of the red line if the thermostat was toast. I'm gonna go out and look for any obstructions on the rad. TIA

Ryan

Injuneer

When it cooled down, did you verify the radiator is full, by looking in the radiator?

Brundle

Yup. Rad is full. Overflow bucket is right where it should be on the cool mark.

Something to mention is that I did change the low coolant sensor a few months back and it was sending false readings (light would come on intermittently when coolant level was fine).

However, I filled the rad back up afterwards and open the bleeder valves and ran it until the air bubbles stopped and coolant came out. Plus the fact its been running fine for the last few months. So I doubt it could be that.

Any other thoughts?

bubba4

Check the thermostat to see if it failed half way open. I've had one do that with me with the same results your seeing (It would run warm but not hot), but , It was not on a LT1 which has a different cooling system. Still it might be worth a check.
Hope it helps. LF

9sevenZ

just a thought, when i bled my system with engine running it didnt bleed correctly and it took a while for it to show (i guess maybe the air bubble took a while to move to the thermostat) anyway i bled it real good with engine off, actually pushing down vertically on the hose with the bleeder and tightening the bleeder with hose pushed down, got quite a bit more air out. Give that a try....you probably have an air bubble stuck in there.

Injuneer

Did the high temperature situation occur at high speed? Did you check the air dam under the front bumper to make sure its still there?

Brundle

Bubba4: was thinking of switching the stat tomorrow. thanks for the suggestion

9sevenZ: i ran the car with the bleeders open yesterday for awhile, and didn't even get the slightest bit of air.....wouldn't really think it would still be air several months (or more) after the fact that i topped up the system tho.
plus the fact that all i did was top up the rad when i changed the sensor. only had to drain it about 1/3. not like it was a full system fluid exchange...

Injuneer: air dam is still there. checked for obstructions on the rad: absolutely nothing. and no, it happens even when idling.

thinking i might try the rad cap tomorrow. dealership parts dept. not open today.
I had a rad cap go bad on one of my previous Zs, and there was such pressure loss that it actually overheated on me....

I'll let you guys know how i make out. any more suggestions welcome of course. thanks.

Brundle

sorry for not updating sooner...but anyways, i changed the rad cap and no go. still running hot. so then changed the stat, and that did the trick.

thanks for the help guys.

AlwaysCode390

Thanks for the update ... it was the stat huh? Atleast thats an easy swap ---

Brundle

ya, all except for popping the old one out. it was really in there good. almost took a mouthful of coolant when it did finally pop out