mf67gto

I have a '14 Z51 M7 that controls coolant right around 204-208. At the Ron Fellows School I was driving 2 different '15s and they controlled right around 194-198. A little investigation on factory thermostat housings (that include the thermostat) shows the following from Gene's Cultrag Catalog:
2014 Thermostat housing/thermostat/gasket #12657137 and $35.95

2015 Thermostat housing/thermostat/gasket #12658723 and $49.50

Anyone know if these are different 'stats and they interchange? At the school they said they did nothing to the cooling systems. Price difference? Could find no other specs.

Thanks

Higgs Boson

This is what I have been suspecting.....On average, people with 2015s have been running 10-15 degrees cooler than 2014s. I bet the 2015 number is cooler.

Fugitive C7

I have also heard that the water pump is different on the 15. Though, i have found no proof of it.

W88fixer

I wonder why GM has chosen such a high temp for the C7s thermostat? I was researching thermostats with a plan to proactively replace the thermo on my G8GT. L79 engine and the thermo has a 186 degree setting, much cooler than the C7.

Emissions related I’d guess but I have no info on that. Don

Kracka

Are the radiator fan tables any different in the stock tune 2014 vs 2015 to compensate for the different thermostat?

10mm_

Are you sure you haven't just been calling '15 owners liars and claiming their t-stats don't open?

10mm_

It's different, but I think that change happened mid-year 14 didn't it?

Higgs Boson

True, I didn't realize you had a 2015, but based on most of your posts, my first inclination is to dismiss.

When three or four others have said the same thing then we have a trend I can get on board with.

Either way, it doesn't change the fact that 2014 owners are seeing quite a bit higher temps and your posts indicating that no one needs a thermostat based on your temps is still inaccurate.

SCHST

I have a 2015 Z51 with 1400 miles. Stock except ARH mid length headers. It always runs 185-190 when hot. On cool mornings it seems to run more around 175. However, I am in WI. The oil & coolant temps seem very close. I have no plans to change thermostats at this point. Hope this helps.

3 Z06ZR1

I think it changed in 2015 according to the installs of the S/C
kits. Needed a change in brackets on the 2015. Or some changed the water pump to a 2014.

Higgs Boson

for sure it helps.....my 2015 1500 with the 6.2 runs 210-220....I wonder if the part number for thermostat or water pump matches the vette for 14 or 15 or if it is different yet.... or maybe it's just that hot here.

Wormwood

Boson,
That 1500 thermostat looks more like a match for LMR's thermostat than anything else, or possibly a MotoRad Tstat.

Wormwood

Higgs Boson

you mean it would benefit from it? yes, I agree. I have the LMR on my vette and it works great, i plan to put one on my truck too in a few months when I save up the money.

10mm_

Lol I never said no one needs a thermostat based on my temps.

Higgs Boson

when you are a year late to the party and we have all been talking about it the whole time and you come in and say, "thermostats are unnecessary, my cars runs at 195," then, yes, that's exactly what you said.

Bill Dearborn

What the coolant runs at doesn't necessarily mean the thermostat is set at that level. Not sure what the setting is on the C7 thermostats but the C5 and C6 thermostats (all versions) were set at 86 deg C which happens to be 186 deg F. Both models run around 200 to 205 on the street. Fan settings and speed have a lot to do with the temperature of the coolant. Usually the fans are turned off when speed reaches 35 mph since they start to block air flow at that speed.

Since GM controls the fan turn on temps so coolant can reach 240 deg when the car is standing still and varies the fan turn on based on AC load (pressure) and coolant temp it is hard to compare. When you see two or more different part numbers for a part from GM all you may be seeing is the constant rolling of part numbers they do over the years. The number can change for a lot of reasons besides a difference in performance or function.

Comparing coolant temps from a car on a track where it is moving at high rates of speed and street driving doesn't give you a true picture. The track car is producing more heat since it is producing a hell of a lot more power/heat due the gas pedal being near wide open but it is going at a lot higher speed so has more cooling air coming in the front. The car running on the street is producing a hell of a lot less horsepower/heat but isn't being cooled as much due to the low performance of the fans and the fact that they aren't on all the time.

Part number 12657137 applies to the 2014 Corvette and a bunch of other vehicles and includes the thermostat housing and thermostat.

Part number 12658723 applies to the 2015 Corvette and no other vehicles and includes the thermostat housing and thermostat.

This could mean the housing changed but the thermostat opening point didn't change or the thermostat opening point changed. I doubt it changed due to emissions reasons because that probably would have rolled over into the other vehicles.

For instance with the coming of the Z06 there may have been a need to change the housing to make some parts fit and they just decided to change all of the cars to simplify things such as using the same housing/thermostat and using the same connecting hoses.

The only way to know is to buy one of each and compare the housings and the thermostat opening temp engraved on the thermostats.

Bill

10mm_

Not what I said either but you can keep making **** up, you're good at that.

The poster above me seems to have a fair grasp on the concept.

Higgs Boson

sure, yeah, ok.

RussM05

Maybe the 2015 'stat has a higher flow rate than the 2014 and same 186 degree rating.

My very early 2014 runs at 208 in traffic and 220 if I'm really pushing out in the Hill Country. Only mod is ceramic coated ARH mid-length headers

davekp78

As I said earlier, My '15 A8 runs 190 in normal cruise and around town. Could it be because of going into 4cyl mode fairly often?
Have to drive about 2hrs each way on I-95 today. Will try it in manual mode which stays in 8 cyl mode and see what happens.