# 2021 GMC Sierra Transmission Temp



## Jdurrance (Feb 3, 2014)

Hello I’ve got a 2021 GMC Sierra 1500 crew cab short bed elevation 8 speed transmission . I’ve got a 7.5 foot ezv fisher stainless on it. I am not plowing a lot of driveways. My driveway my parents and my uncles no big driveways.
My uncle asked me to plow his in laws for the first storm. Fairly big area. It s was a little ways away to get there. Just for curiosity I made sure then to keep an eye on the transmission temp. I didn’t think of it doing my driveway or my uncles. But doing his in laws driveway the temp kept going up I turned the truck off at 220 to let it cool.
I had a 2015 Silverado the temp on that I’ve seen about 205 not plowing. Didn’t have a plow on that one.
My questions is is that catastrophic? Was not planning on plowing with it when I got it. Google search shows there good to about 260 degrees but I’m not that knowledgeable in transmissions. Thanks for any input.


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## jonniesmooth (Dec 5, 2008)

That's the trans temp or the engine temp?


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## Jdurrance (Feb 3, 2014)

Transmission. Engine temp stayed about 210 normal.


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## dieselss (Jan 3, 2008)

1 trans cooler if your doing this as a normal gig.
2 don't ever shut it off, put the trans in N or P and actually rev it to about 2k to cool it down.

Were you pushing it really hard?


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## Jdurrance (Feb 3, 2014)

Ya I just figured out not to turn it off now. It was very wet and heavy snow. I’ve got experience plowing. Have had plows on half ton trucks before but just got paranoid about this one. I wasent beating on the truck by no means. Going slow just chugging along. Once I got back on the highway headed back air flow temp dropped to about 160 fairly quickly.


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## dieselss (Jan 3, 2008)

If it was that bad, maybe 4lo next time


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## Jdurrance (Feb 3, 2014)

Ok thank you.


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## EWSplow (Dec 4, 2012)

The plow was probably blocking air to your radiator while driving. 
Also, I'm not sure but if it doesn't have a towing or plow package, there may not be an external transmission cooler. 
Never mind the 1st part, I didn't read your 2nd post.


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## Jdurrance (Feb 3, 2014)

So I know it does not have the plow prep I know that for sure but it does have the tow package. But I just don’t know if it has the transmission cooler. 
I was concerned with the transmission temp being that high. Weather or not that would have caused any problems. Seems fine but not entirely sure if being that high would have caused any major problems. Obviously now I would know to keep an eye on it and try and remedy it while plowing. 
I didn’t realize until after I bought the truck it only has a single speed transfer case four high only. It does have a “simulated four low” I might try that and see if that makes a difference next storm.
Thanks everyone for the reply’s.


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## jonniesmooth (Dec 5, 2008)

Just covering the basics.
You had the tow/haul mode activated, right?


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## Jdurrance (Feb 3, 2014)

On tow/haul I did about half way through I didn’t think about that until I started plowing there. Next storm I’m going to put tow/haul on and maybe keep in 1st gear see if that helps maybe.


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## leolkfrm (Mar 11, 2010)

tow/haul and easy an the pedal


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## Jdurrance (Feb 3, 2014)

Thanks everyone for the responses. I was getting concerned about any damage or if I should go and get a fluid change on the transmission. It’s only got 9000 miles on it. I understand the warranty problems and what not with a plow. 
Sounds like I’ll keep an eye on the temp plowing in the future.


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## SHAWZER (Feb 29, 2012)

Not familiar with new GMC trucks , what does simulated 4 low mean ?


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## Jdurrance (Feb 3, 2014)

SHAWZER said:


> Not familiar with new GMC trucks , what does simulated 4 low mean ?


On the new and maybe even past couple of years, GM 1500 trucks except for I believe z71 and trail boss and maybe the at4 it only has 4hi no 4lo. But it has a setting in 4hi that is supposed to reduce power and do other things to "simulate" 4lo but it is not physically geared differently. I didn't realize it until basically everything was signed for the truck. And it was the time when trucks were even harder to get. It was the only crew cab 1500 with a 5.3 on the lot.


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## Western1 (Dec 4, 2008)

SHAWZER said:


> Not familiar with new GMC trucks , what does simulated 4 low mean ?


Could be virtual 4 lo?


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## Western1 (Dec 4, 2008)

I would change fluid once a year regardless


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## Jdurrance (Feb 3, 2014)

Western1 said:


> I would change fluid once a year regardless


Ok. Might do that. Anyway.


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## Mountain Bob (Nov 12, 2017)

I did notice this in the manual-- But it is a 2019 one-

Caution
If the vehicle does not have the
snow plow prep package, RPO
VYU, adding a plow can damage
the vehicle, and the repairs would
not be covered by the vehicle
warranty. Unless the vehicle was
built to carry a snow plow, do not
add one to the vehicle. If the
vehicle has RPO VYU, then the
payload the vehicle can carry will
be reduced when a snow plow is
(Continued)
Caution (Continued)
installed. The vehicle can be
damaged if either the front or rear
axle ratings or the Gross Vehicle
Weight Rating (GVWR) are
exceeded.


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## Jdurrance (Feb 3, 2014)

Western1 said:


> Could be virtual 4 lo?


Basically yes that is my understanding of it.


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## Mr.Markus (Jan 7, 2010)

Western1 said:


> I would change fluid once a year regardless


I worked my 07 pretty hard, the trailer never came off it in the summer, and it plowed and salted all winter. I changed the trans filters and fluid every spring and fall. 600k without a problem ever.


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## thelettuceman (Nov 23, 2010)

Jdurrance said:


> On tow/haul I did about half way through I didn't think about that until I started plowing there. Next storm I'm going to put tow/haul on and maybe keep in 1st gear see if that helps maybe.


Remember to turn off traction control.... this will save your brakes


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## kg26 (Feb 5, 2013)

leolkfrm said:


> tow/haul and easy an the pedal


Ok im learning something here. Why tow/haul, or why would he say he would keep it in first gear?


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## dieselss (Jan 3, 2008)

Less shifting, and tow haul holds it higher rams longer before shifting


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## kg26 (Feb 5, 2013)

dieselss said:


> Less shifting, and tow haul holds it higher rams longer before shifting


So if it is light and fluffy snow, would you use 4hi in drive? Or what's the proper set up for this situation


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## leolkfrm (Mar 11, 2010)

light and fluffy i would plow in 2 wheel drive, but i have counterweight in the bed for traction, always tow/haul mode


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## kg26 (Feb 5, 2013)

leolkfrm said:


> light and fluffy i would plow in 2 wheel drive, but i have counterweight in the bed for traction, always tow/haul mode


How much counter weight vs how much the plow weighs? Ive got a 7 poly coming that is about 400lbs I put that much in sand bags back there over the axel.


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## leolkfrm (Mar 11, 2010)

i jinxed myself, had to plow in 2wd, linkage for transfer case must have broke, so no 4wd


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## leolkfrm (Mar 11, 2010)

should be between the axle and tailgate


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## Jdurrance (Feb 3, 2014)

Well update I put some more ballast in the bed. Avoided four wheel drive. Which is kind of what I always did with other trucks but this one thought it would be easier on the truck. Transmission temp reached 200ish after plowing for a little bit I was pretty much done with my uncles driveway at that point.


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## SnowHampshire (Nov 8, 2020)

Jdurrance said:


> Well update I put some more ballast in the bed. Avoided four wheel drive. Which is kind of what I always did with other trucks but this one thought it would be easier on the truck. Transmission temp reached 200ish after plowing for a little bit I was pretty much done with my uncles driveway at that point.











Fiddy percent off, buy that thing...easy install


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