Cold Weather Thermostat issue?

muhsfink07 · January 16, 2020

Hi guys,

I've got a 2016 GMC Sierra 1500 5.3 and recently this winter I have noticed that when it gets "cold" i.e. anything roughly 45 degrees or below the temp gauge doesn't quite get to center. It stays roughly 1 dash below center even after allowing the truck to fully warm up. During my commute which is on city streets it doesn't warm up all of the way. I have included a picture to demonstrate what I am seeing. I cannot remember this ever happening before although I am reluctant to take it in if there is anything I can do on my end to fix it. Does anyone know of any TSB's out there that might address this issue? I have done some searching on the forum but nothing seems to quite replicate this. Most of the TSB's seem to involve radiator issues if i'm not mistaken? Also this picture is taken when it is 10 degrees outside.

Anyway, thanks for all of your help!

Keep Trucking!

Snowcamo · January 16, 2020

Completely normal. Enjoy no worries.

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It's Tim · January 16, 2020

You can always check the temperature of the cooling system with a cheap IR heat gun.

muhsfink07 · January 16, 2020

The thing is I can't remember noticing this any other winter... I do tend to notice things like battery charge/engine temp etc.

Thanks!

Snowcamo · January 16, 2020

It'll be like that due to the cold weather and properly functioning cooling system. Even if the stat functions properly the radiator will cool down the coolant quickly.
I notice mine stays there up to 65°F or so after I cleaned the gunk off the radiator. Its not a bad thing.

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newdude · January 16, 2020

3 hours ago, muhsfink07 said:

Hi guys,

I've got a 2016 GMC Sierra 1500 5.3 and recently this winter I have noticed that when it gets "cold" i.e. anything roughly 45 degrees or below the temp gauge doesn't quite get to center. It stays roughly 1 dash below center even after allowing the truck to fully warm up. During my commute which is on city streets it doesn't warm up all of the way. I have included a picture to demonstrate what I am seeing. I cannot remember this ever happening before although I am reluctant to take it in if there is anything I can do on my end to fix it. Does anyone know of any TSB's out there that might address this issue? I have done some searching on the forum but nothing seems to quite replicate this. Most of the TSB's seem to involve radiator issues if i'm not mistaken? Also this picture is taken when it is 10 degrees outside.

Anyway, thanks for all of your help!

Keep Trucking!

Looks normal, especially if you have a short commute. How many miles is your drive? Do you remote start in the cold?

If I start off after letting run 3-5 minutes on remote start, the needle will be at or just above 160F (which BTW, is a dummy gauge until it hits operating temp). It takes about 2-4 miles to reach 210F on the gauge.

mookdoc6 · January 16, 2020

4 hours ago, muhsfink07 said:

Hi guys,

I've got a 2016 GMC Sierra 1500 5.3 and recently this winter I have noticed that when it gets "cold" i.e. anything roughly 45 degrees or below the temp gauge doesn't quite get to center. It stays roughly 1 dash below center even after allowing the truck to fully warm up. During my commute which is on city streets it doesn't warm up all of the way. I have included a picture to demonstrate what I am seeing. I cannot remember this ever happening before although I am reluctant to take it in if there is anything I can do on my end to fix it. Does anyone know of any TSB's out there that might address this issue? I have done some searching on the forum but nothing seems to quite replicate this. Most of the TSB's seem to involve radiator issues if i'm not mistaken? Also this picture is taken when it is 10 degrees outside.

Anyway, thanks for all of your help!

Keep Trucking!

The updated cycling thermostat was issued sometime in 2016? Mine did exact same thing and being overly goofy I couldn't deal with a dummy gage that already is not very accurate to be even more inaccurate. Replace it can't remember 30.00 and it will land back dead in the middle on Hot engine.

Bash74 · January 17, 2020

I am not sure about it in the temps that you mentioned but I know when the temps are -25 and below if I turn the heat on before the needle gets to the middle it will never get to the middle during my 15mile drive to work. Also the heat is not as hot as it is when the gauge is in the middle. So I just wait till it gets to the middle to turn the heat on.

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CamGTP · January 17, 2020

My gauge is roughly in the same spot all the time unless stopped for a decent period of time. My thermostat is not working properly as I have HP Tuners and can watch my coolant temps. It used to stay up around 190-195 all the time and now I can barely creep above 170-175 on the open road.

If I floor it and drive it hard it will get the coolant temp up to around 200 but drops like a rock down to 170 again.

Grumpy Bear · January 17, 2020

There is a small hose that runs from the thermostat housing to the catch tank. It's a minimum flow bypass to keep the pump happy. The thermostat does no have a bleed hole in it like the old 54 mm units did. In cold weather like this (20F) it will flow enough to keep the motor below the set point just a few degrees. This really is quite normal.

BTW, that 160 F mark on your gauge is more like 100 F.

19 minutes ago, CamGTP said:

My gauge is roughly in the same spot all the time unless stopped for a decent period of time. My thermostat is not working properly as I have HP Tuners and can watch my coolant temps. It used to stay up around 190-195 all the time and now I can barely creep above 170-175 on the open road.

If I floor it and drive it hard it will get the coolant temp up to around 200 but drops like a rock down to 170 again.

Also normal. If I had more confidence I'll install a carburetor jet in that bypass line.

CamGTP · January 17, 2020

It's not normal if last winter my coolant temps stayed around 185-195 all the time and this winter it barely cracks 170. My parents have the same truck as me, theirs stays at or around 195 no matter what the temp is outside.

I'm too lazy to change my thermostat and it's also cold. It can wait til spring time when it's back into the 40's.

Grumpy Bear · January 17, 2020

1 hour ago, CamGTP said:

It's not normal if last winter my coolant temps stayed around 185-195 all the time and this winter it barely cracks 170. My parents have the same truck as me, theirs stays at or around 195 no matter what the temp is outside.

I'm too lazy to change my thermostat and it's also cold. It can wait til spring time when it's back into the 40's.

Sorry, not what I meant Cam. I meant it is normal to fall rapidly when it opens after being below the open temperature for a length of time like first thing or low loads as you had indicated. I'm poor at being clear to others. Sorry. Always seems sharp in my mind but you can't read my mind. A good thing I think....for us both. LOL.

gone_fishing · January 17, 2020

I have a ScanGauge II in my Sierra and can monitor engine coolant temp. About a year ago I started to notice the engine temp gauge not making it to the normal 12 o'clock position. This was even a long highway drive in summer temps. ScanGauge would be in the mid 180's. Once cooler fall temps set in, it was closer to 175F. Decided to replace the t-stat and temps came back up to around 200. Found a few other reports claiming the same issue. Seems the t-stat wears out and it opens too soon (which I guess is better then too late). FYI, replacing the tstat is pretty easy on these engines.

Grumpy Bear · January 18, 2020

5 hours ago, gone_fishing said:

I have a ScanGauge II in my Sierra and can monitor engine coolant temp. About a year ago I started to notice the engine temp gauge not making it to the normal 12 o'clock position. This was even a long highway drive in summer temps. ScanGauge would be in the mid 180's. Once cooler fall temps set in, it was closer to 175F. Decided to replace the t-stat and temps came back up to around 200. Found a few other reports claiming the same issue. Seems the t-stat wears out and it opens too soon (which I guess is better then too late). FYI, replacing the tstat is pretty easy on these engines.

May I ask how many miles we placed on that first thermostat? thanks.