Dfwz06

Guys, out of nowhere today my car takes the rev match off. Then I get to where I'm going and turn the car off, and the radiator fan stays on for 16.5 minutes. It's 65 degrees out, so I'm like wtf.
Then I get back in the car and start driving. After 15 minutes I check to see what the coolant temp is. It shows 100, which is the lowest reading it can have. Then I notice the A/C system won't blow cold air. Then about 20 miles later the engine light comes on.

Any ideas?

BEZ06

Check your coolant level.

Sounds like it's low, or maybe completely empty!

Have you had any work done lately?

Have you seen any coolant fluid on the floor of your garage or parking spaces?

I wouldn't drive the car until I figured this out!!!

.

Dfwz06

Coolant level is full. I checked it and it was only warm, not hot.
No work done in the last month.
No fluids on garage floor.

SUB VETTE

You need to pull trouble codes with a code reader to properly figure out your problem(s)

robertbruce

Thermostat ?

wagoetzmann

Mine acted the same way with a 160 F thermostat and no tune to allow it to work correctly. I had to disconnect the battery to get the fan to stop running and reset everything. Put the original 195 F thermostat back in and everything went back to normal.

Dfwz06

I have a 160 thermostat, but they should've got it in he tune. It's been fine for 4 weeks.
Did your car have all the same symptoms?

wagoetzmann

See this thread starting about post #20.

https://www.corvetteforum.com/forums...s-the-ls3.html

Dfwz06

Thanks man. Exactly what mine is doing. Did you tune it or just try it with stock tune?

AEK

I just wanted to add to this thread, in case this happens to anyone else. Apologies that I have a Z51 and not a Z06, it's the behavior of the car described above that was the same for me.

I'm the second owner of my '2014 Z51 -- the first owner did some mods (aluminum radiator, AP Racing front brakes and F/R rotors, bigger wheels and tires, and various other little things) because he tracked the car. When he moved up to the Camaro Z1 LE, I bought this car. I really like the car.

I'm in the SF Bay Area, and on the very first time I drove the car on the highway, I noticed that it was running too cool -- not at the midpoint of the temperature gauge, but several ticks below it (around 195F indicated). And I noticed that it took a long time -- too long -- to warm up to the point where the yellow "warning" bar on the tach finally turned off. In fact, I even saw it reach full operating temperature once, then drop back down to "yellow tach", all on the same drive, in 50-70F temperatures (!). Then, a few days later, I took it out on a 49F night, and the same thing that Dfwz06 mentioned happened to me (though I got home before the CEL light came on). Fans all running full speed, I ended up having to disconnect the battery. I stopped driving the car.

So, after thinking about this for a while and reading through the forums, I decided to check the thermostat. I pulled it out, and frankly it looked fine. I knew that the radiator had been upgraded, and it crossed my mind that maybe this was a Mishimoto 160F thermostat inside the housing, but it looked totally stock. So I was kinda stumped, but decided to order a new thermostat (assembly) anyway. To make a long story short, I received a new thermostat, it looked identical to the old one, I put the new one in, drove it on a 55F day, and now things are operating correctly, in my mind. Warm up is pretty quick, and then the water temp stabilizes at the halfway mark of the water temp gauge (around 220F). The oil temps seems correct as well. It appears my problem is solved.

The OLD thermostat had a February 2015 build date, with P/N 12666569.
The NEW thermostat had a late 2017 build date, with P/N 12674639.

Note that since my Z51 is a 2014, that OLD thermostat could not have been originally on the car.

I've found that the 12674639 thermostat (also called "water outlet" and "engine coolant thermostat housing") is often listed as being for a whole bunch of GM SUVs, etc. but not always for the Corvette. But, it seems to work on my Z51 very nicely. The 12666569 part is listed as being discontinued.

The PN on the thermostat (housing) is viewable very easily when you open the hood -- it's on the top flange, closer to the center of car/engine centerline. The datecode is on the other side of that "bent" top flange.

sammy burks

You donot need to change the Thermostat back just disconnect the battery to get the fan to stop running and reset everything & you will be good to go.

AEK

I didn't remove the thermostat to stop the fans, I disconnected the battery as per my post. I removed the thermostat to identify and inspect it, because it seemed the most likely culprit. Replacing it with PN 12674639 solved the problem. I dunno where the PN 12666569 came from, but it was the source of the problem. If I'm to believe my temperature gauge (GM handled the water temperature readings (gauge and center display) differently on the '2014 C7 than on later cars), the OLD thermostat (12666569) was around 20 degrees cooler than the NEW thermostat (12674639 ).

As an aside, there was no temperature marking on the (bare) thermostat in the OLD thermostat housing -- just a "B16 C207" in very small letters on the tip of the brass bulb of the thermostat. I didn't mark down what was on the tip of the new thermostat. The Mishimoto 160F (bare) thermostat is constructed a little bit differently from the stock GM thermostats, so it was clear that it wasn't a Mishimoto 160F thermostat.

Disclaimer: The Z06 may very well use a different thermostat, compared to the Z51. My posts here are about the Z51 thermostat, in a '2014 C7 Z51.