brentil

I highly recommend also replacing the thermostat with one from a 2016 MY or newer now too. You've likely damaged the old one with the high heat and the newer ones open at a slightly lower temp than the 2014MY thermostat.

rastolpho

Thanks for the info! I’ve actually been looking at that as well.

Reason was due to the halo around the RPM gauge showing when cruising down the highway, noticed it during the winter.

I’m assuming with a lower thermostat (I believe a 180 is ok?) that would trigger even more? I’m not worried about that really, just want the engine to be happy and last a long time. 😂

If you happen to know the part number I would appreciate it!

eboggs_jkvl

Put the stock t-stat in. Saves you from problems.

Elmer

rastolpho

Just some quick reads while driving, avg of 175 engine temp, oil at around 185ish or so while cruising at 75mph and at roughly 72 degrees outside.

But when on stop and go traffic, engine goes to about 200, oil goes up to 200 or so.

When I ran into the overheat issue it was on stop and go traffic.

Curious, original Tstat on the 2014 is 194?

brentil

The 2014 has a 207°F thermostat which they then replaced with a 194°F thermostat for the 2015-2019 model years. You'll see a 2014 with an original thermostat idle at 210 F and a later model idle at 200 F instead. So if you were idling at 200 F that means you already had a replaced newer thermostat. I'd still replace it again with a newer version again as it helps just keep the engine slightly cooler overall but might have been damaged with the heat going to high. The overheating issue is due to the original fan faulting and failing to turn on. I'm honestly surprised there was never a recall for this.

rastolpho

Thanks for the reply!

Yes, so I went ahead and ordered a new Tstat anyway since it’s an easy swap. The 2015 and after model.

Since I don’t know the entire history on the car, I’m also doing a full coolant service (following the instructions I found here on the forums) so I can be sure it’s all new along with the new fan.

Its also due for an oil change sitting at 1% so doing that as well.. Will be a busy weekend in my garage. 😂

Appreciate all the responses!

Red86Cfour

I replaced my 2014 thermostat when I got the zero temp/screaming fans problem. Stock part according to the GM guy is 217, which was stamped both on the new part and the part I removed. I'm not terribly thrilled with it running at 217 all the time so I may change it out for a lower temp from a 2015

And just to be a bit more clear about the original problem, it isn't with the fans, but with the controller which can't be bought separately. It goes to sleep during sustained highway driving, so that when you come to stop for a slowdown or exit, it won't turn the fans back on. The zo6 controller obviously doesn't have this problem, and in addition the fans are higher wattage and move more air when needed. You really would have thought this would be a recall problem.

brentil

The fan not turning on and the 0 coolant temp are actually 2 different issues. I had both of them happen with my MY14 at different times. There's a reason GM lowered the temp starting with MY15 because it results in a 3rd problem over time unrelated to the other 2. I'm also surprised there wasn't a recall for this as well. The original TB I saw when it first happened mentioned the higher constant temps could cause the plastic thermostat housing to slowly deform over time which can cause a bubble to form and then cavitation resulting in fluid starvation. First time I had overheating happen was because of that and they replaced the new 2015 housing but put a stupid MY14 thermostat back in which I promptly replaced with the newest version myself.

There's several problems with the MY14 that can happen, I've experienced all of them separately multiple times over the 7 years I owned my MY14 as the original owner. I got GM involved a couple times with my dealership because of the continued issues. I live in FL so it's always hot and we always run the AC making extra load, and I daily drove my car and did multiple 4k+ mile road trips too so had nearly 100k miles.

1. Higher running temp of the MY14 thermostat can warp the thermostat housing resulting in overheating. Replace it with a new MY15 or newer housing and thermostat.
2. The MY14 fan controller can become unresponsive resulting the in fans not turning on when the car requests them resulting in overheating. Replace with the Z06 fans as they have higher air flow and their controller does not have issues.
3. If the thermostat is damaged from a previous overheating event or the housing being warped it will get stuck open always flowing coolant keeping the coolant temp too low all the time. There's some logic in the engine controller that if that value is too low too long the engine temp sensor reading drops to NULL (not 0 but NULL). It's not a sensor issue (replaced all sensors) or a harness issue (replaced harnesses). When the car engine temp vanishes it puts the car in limp mode which results in the fans going to 100%, rev match disabled, and AC disabled (nightmare in FL). Solution is to replace the thermostat housing with a MY15 and thermostat itself from MY15 or newer.
4. If you have an overheating event for any reason it can warp the thermostat housing causing new issues. Replace it with a MY15 or newer and the thermostat.
5. If you have an overheating event for any reason it can warp the coolant hose to and from the radiator, inspect to replace.

rastolpho

Thanks for all the info! I've read about these issues and how it can snowball into other issues if not fixed "all at the same time", hence why I'm doing a new Tstat with the new 600W fan from the Z06 and doing a full coolant swap (with at least 3 distilled water runs to get it as much of the old one out as possible). I'll also check the coolant hose while doing the fan. Is this an easy swap as well if the fan is already out? Thinking I might do that so that other than the radiator itself, that system is back to almost its original state...

Doing an oil change as well, I can see my Sunday being quite busy but I'm excited to get it all taken care of at once!

brentil

I lucked out that the one time my hoses were damaged was under warranty so they replaced them too so I unfortunately don't know how hard they are to replace. You can visually inspect them and feel them by hand looking for odd bulges usually around where they touch the radiator or engine.

rdbragg

I just had a similar occurrence on my 2014 and wanted to share my findings. I overheated after a nice long freeway drive and then getting off and into some stop and go. I also did not hear my fan running and assumed that an intermittent fan was the issue. I drove it home on the freeway after letting it cool and it did not overheat, but it did puke out of the surge tank vent tube on the bottom when I stopped the car. It would do this reliably and the fan was working. I also noticed that the system was not pressurizing properly and I could easily squeeze radiator hose when it should have been firm. I replaced the fan, thermostat and the pressure cap, but it still would puke out the surge tank vent tube after being warmed up and the engine turned off. It was also still not pressurizing. I decided that it had to be some weird break in the surge tank and replaced it and that cured the issue. Now the system pressurizes and does not leak from the vent tube. So a break in the seam of the plastic surge tank seems to have been the true cause coupled with the odd "fan fails to turn on" condition. I feel it was more than one thing, but the real problem was the system failing to hold pressure due to some hairline fracture in the surge tank at a seam between the top and bottom halves. Smooth, empty roads to all!!

eboggs_jkvl

Might be a coincidence but in 2014, when this issue first hit, I doubt if the surge tank was defective as it was new. The fan controller built in to the fam unit was the problem. The Z06 fan replaced the fan controller and fixed the problem 100% of the time.

You went into a lot of testing and may have found something but the controller was what we had screwing us.

Elmer