Good Sam Club Open Roads Forum: GM Yukon XL Denali Transmission Temps
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 > GM Yukon XL Denali Transmission Temps

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Bionic Man

Colorado

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Posted: 06/17/19 08:06am Link  |  Quote  |  Print  |  Notify Moderator

My main tow vehicle is my RAM CTD, but when we take the RV as well the truck has to pull my 7000 pound boat. So then we use my 2011 Yukon XL Denali to tow the Malibu.

It has always run hot - both engine and transmission. Especially in the mountains.

Last week we went on vacation. Pulled the boat to Steamboat, Colorado. This was up I70 to Hwy 40 for those familiar with the area. Going up it wasn’t terrible but coming home it was. Up Rabbit Ears pass, I ran it somewhat hard up until about a mile from the top. Engine temp was about 3/4 up the gauge but the transmission temp is what was worse. Even slowing down to run about 4000 RPMs in second, it was 254* at the top.

I ran slower up to the Eisenhower tunnel, but couldn’t keep the tranny below even 240*. Again at the top, it was at 250* - even though I further slowed down. Trying to force it out of 2nd and into 3rd didn’t help (and it was hard to maintain any speed in 3rd).

I’ve? asked two GM dealers as well as an independent transmissio?n shop about it in the past and they told me that is just what to ex?pect towing 7000 pounds with a half ton SUV through the m?ountains and that it would be fine for short periods of time at those temps.

The Yukon does have an auxiliary transmission cooler from the factory.

Is anyone else seeing that high of temps? Is there some sort of idiot light that will come on or will the engine defuel if the temps get too high?


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SidecarFlip

SE Michigan

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Posted: 06/17/19 08:13am Link  |  Quote  |  Print  |  Notify Moderator

A bit too warm and factory coolers are marginal at best. I'd be adding an auxillary cooler like a Hayden Swirl Cool 2 pass . I run 2 of them on my F350 and my trans temp never gets above 195.


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ShinerBock

SATX

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Posted: 06/17/19 08:52am Link  |  Quote  |  Print  |  Notify Moderator

Those are high temps. Not high enough to do any immediate catastrophic damage, but high enough to lower the life of your fluid and possibly trans internals if not changed. I would recommend a trans fluid flush ASAP.


Is the fluid that is in their from the factory?


If so trans fluid breaks down over time and loose some cooling and pressure holding ability over time so not only is it not cooling as well, but it is also creating more heat due to higher line pressures. If the fluid that is in there is from the factory and over 75k miles, then I can see your temps getting up there in those conditions.

carringb

Corvallis, OR

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Posted: 06/17/19 09:46am Link  |  Quote  |  Print  |  Notify Moderator

Can you hear the cooling fan kicking on? Steep grades are doubly bad because of the decreased airflow, and if the fan isn't working, you have no chance at keeping the temps down.


Bryan

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Lwiddis

near Jawbone Canyon, CA

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Posted: 06/17/19 11:52am Link  |  Quote  |  Print  |  Notify Moderator

"but couldn’t keep the tranny below even 240*. Again at the top, it was at 250"
I'd change the transmission fluid after a run like that. See:

https://www.bing.com/images/search?view=detailV2&id=92E13F6E0A8E2466FFB6196023AE0FE2D14FDCC0&thid=OIP.fq_fH_4y-DgYmpU8I6EhuAHaGT&mediaurl=http%3A%2F%2Fhome.earthlink.net%2F~jrshelton%2Fsitebuildercontent%2Fsitebuilderpictures%2Ftrans_failure_temp_chart.jpg&exph=506&expw=595&q=transmission+temperature+chart&selectedindex=1&ajaxhist=0&vt=0&eim=1,2,6


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Bionic Man

Colorado

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Posted: 06/17/19 12:11pm Link  |  Quote  |  Print  |  Notify Moderator

ShinerBock wrote:

Those are high temps. Not high enough to do any immediate catastrophic damage, but high enough to lower the life of your fluid and possibly trans internals if not changed. I would recommend a trans fluid flush ASAP.


Is the fluid that is in their from the factory?


If so trans fluid breaks down over time and loose some cooling and pressure holding ability over time so not only is it not cooling as well, but it is also creating more heat due to higher line pressures. If the fluid that is in there is from the factory and over 75k miles, then I can see your temps getting up there in those conditions.


I had the tranny fluid changed at 82,000 miles. It now has a little over 100k.

Bionic Man

Colorado

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Posted: 06/17/19 12:13pm Link  |  Quote  |  Print  |  Notify Moderator

carringb wrote:

Can you hear the cooling fan kicking on? Steep grades are doubly bad because of the decreased airflow, and if the fan isn't working, you have no chance at keeping the temps down.


I am not sure if I have heard the cooling fan come on or not. Surprised that I haven’t paid attention to that as I can certainly hear it come on in my truck.

Bionic Man

Colorado

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Posted: 06/17/19 12:20pm Link  |  Quote  |  Print  |  Notify Moderator

I called a Chevy dealer this am. He confirmed by the VIN that I have the heavy duty cooler on my suv. He basically said “that’s what I should expect”.

Called a transmission shop near me and he didn’t exactly disagree with the Chevy dealer. He said that if temps get above 270 that is when damage occurs. But he said that between the tranny temp and the engine temp both being high he would like me to bring it in and take a look.

I’m torn as I asked the same question on a boating forum I frequent and several people have reported back that they see the same temps in extreme conditions.

I don’t want to kill the tranny as I want this vehicle to last another couple years before I cycle it out of the fleet. But I also don’t want to spend money just to spend money. It runs normal temps until I hook my boat up to it. Not sure how they troubleshoot without recreating the issue. The Chevy dealer basically said that same thing.

gopherslayer

WI

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Posted: 06/17/19 03:42pm Link  |  Quote  |  Print  |  Notify Moderator

I’d put a bigger cooler on it. They aren’t expensive.

marcsbigfoot20b27

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Posted: 06/17/19 03:54pm Link  |  Quote  |  Print  |  Notify Moderator

Tru-cool 40K. Google or amazon it.

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