2011 Yukon Denali 6L80

[Jhaley213]

Sorry for the third post in 3 days, my other truck is a 2019 Ram so this truck is very new to me and I want it to last. I have a 6L80 transmission 6.2 and I’m wondering what temp it should be running at? Is it different on hot days in New England? Today it’s over 100 degrees and it ran between 185 and 190 on a half hour or so ride. It generally seems to shift very well but I had to pull out quick today and have it gas pretty hard and it took right off but seemed to take kind of a hard shift. Is this something I should worry about or fairly normal? I just put the plug in AFM delete in today 20 minutes before this if that helps

 

[SpareParts]

Seems like i read 220 is about the max you want.

 

[2017sltXL]

That is not out of the ordinary for that era, and that is not that bad with 100* ambient temps.
How is the fluid? These are easy to do a line flush right at the trans cooler, replaces all the fluid without dropping the pan.
That said, I would only do that if I knew the filter was replaced at some point depending on the milage. If you don't know the service history then it's best to drop the pan.

 

[Marky Dissod]

Following chart applies to Dexron3:
176°F / 80°C ....... 64,000-96,000 Miles ... Ideal Automatic Transmission Fluid Temp
194°F / 90°C ....... 32,000-48,000 Miles ... Max Recommended Sustained Temp
212°F / 100°C ..... 16,000-24,000 Miles ... Pressure Drops, MpG increases, longevity & durability decreases

230°F / 110°C ........ 8,000-12,000 Miles ... Varnishes Form
257°F / 125°C .......... 4,000-6,000 Miles ... Seals Harden
275°F / 135°C .......... 2,000-3,000 Miles ... Clutches Slip
293°F / 145°C .......... 1,000-1,500 Miles ... Oil forms carbon, seals and clutches burn
320°F / 160°C ... ... ... transmission line sensor triggers pcm's Hot Transmission Mode

Although Dexron6 & younger ATFs - especially GM/Allison ATF! - are clearly superior,
mind that the hotter the ATF, the more quickly it gets 'old'.

... 220F is about the max you want.

Any hotter than 221F / 105C, I'd research better ATF cooling, as well as better ATF.
Yes, the 8L90, 10L80, & GM's 'Allison?' 10L1000 all use ATF superior to Dexron 6.

 

[rdezs]

The 2014 shifts harder the higher you go in RPM. I assume it was more line pressure when you're really getting on it. (Which is a good thing)

Temperature wise, our 2014 runs an average of 155° going down the freeway at 70 mph on a hot day. I don't think I've ever seen it hit 170°. But 190° is not an issue with dexron 6. Maybe time to replace the ATF? (I've done it every 30,000 miles since new)

 

[Jhaley213]

Following chart applies to Dexron3:
176°F / 80°C ....... 64,000-96,000 Miles ... Ideal Automatic Transmission Fluid Temp
194°F / 90°C ....... 32,000-48,000 Miles ... Max Recommended Sustained Temp
212°F / 100°C ..... 16,000-24,000 Miles ... Pressure Drops, MpG increases, longevity & durability decreases

230°F / 110°C ........ 8,000-12,000 Miles ... Varnishes Form
257°F / 125°C .......... 4,000-6,000 Miles ... Seals Harden
275°F / 135°C .......... 2,000-3,000 Miles ... Clutches Slip
293°F / 145°C .......... 1,000-1,500 Miles ... Oil forms carbon, seals and clutches burn
320°F / 160°C ... ... ... transmission line sensor triggers pcm's Hot Transmission Mode

Although Dexron6 & younger ATFs - especially GM/Allison ATF! - are clearly superior,
mind that the hotter the ATF, the more quickly it gets 'old'.

Any hotter than 221F / 105C, I'd research better ATF cooling, as well as better ATF.
Yes, the 8L90, 10L80, & GM's 'Allison?' 10L1000 all use ATF superior to Dexron 6.

@Marky Dissod i think I’m just going to pull the pan and change the fluid, as it’s new to me I want to make sure I know when the last time everything was done. I already did the oil with royal purple and I figure I might as well do the diffs too

 

[Jhaley213]

The 2014 shifts harder the higher you go in RPM. I assume it was more line pressure when you're really getting on it. (Which is a good thing)

Temperature wise, our 2014 runs an average of 155° going down the freeway at 70 mph on a hot day. I don't think I've ever seen it hit 170°. But 190° is not an issue with dexron 6. Maybe time to replace the ATF? (I've done it every 30,000 miles since new)

@rdezs i think I’m just gonna change it, it would be crazy to risk it

 

[rdezs]

When you open up your box with your transmission filter, you might find a new grommet that goes up in the transmission. 99% of the time the one you have is just fine. Just push your filter up there.

In the unusual situation where your filter won't stay up because that grommet is wasted, it takes a blind hole bearing puller and a lot of force to get it out. You'll know it's a rubber grommet encased in steel. The last one I changed took more than a couple hard hits with the slide hammer and the blind hole bearing puller.

 

[rdezs]

@Marky Dissod i think I’m just going to pull the pan and change the fluid, as it’s new to me I want to make sure I know when the last time everything was done. I already did the oil with royal purple and I figure I might as well do the diffs too

Front diff, remove the filled plug first to make sure you can get it out. 18 mm box and wrench... Tap with a hammer to break loose if necessary. Make sure the box end wrench is seated squarely on the fill plug. The head of that fill plug isn't very tall, and for some stupid reason it's tapered in towards the end. Many, many have been rounded off with a 12-point socket that's hard to get on there square. Same thing if you try an impact. Replacements are not expensive, I would suggest you have one on hand before you dive in. Heating it up carefully with a propane torch does seem to help. Penetrating oil is useless, as under that flange there's a rubber seal.... So the oil can't get to the threads.
If it's been on there forever and never changed and you round off the head, it only takes a minute to weld an old socket onto it. (1/2 drive preferably, then you can break it loose easy) If you don't have a welder, most shops will quickly spot weld a socket on for you for a nominal fee.

Drain plug is easy. No issues with those.

 

[rdezs]

As for dropping the transmission pan, at least on the 2010 through 2014 models the y-pipe is just slightly in the way. With a pry bar or crowbar, you can flex it down a bit to clear the pan after you've removed the pan bolts. You only have to flex it down about half inch or less. The heat shield on the passenger side of the transmission usually has to come off, only takes a minute.

 

[Jhaley213]

That is not out of the ordinary for that era, and that is not that bad with 100* ambient temps.
How is the fluid? These are easy to do a line flush right at the trans cooler, replaces all the fluid without dropping the pan.
That said, I would only do that if I knew the filter was replaced at some point depending on the milage. If you don't know the service history then it's best to drop the pa

Front diff, remove the filled plug first to make sure you can get it out. 18 mm box and wrench... Tap with a hammer to break loose if necessary. Make sure the box end wrench is seated squarely on the fill plug. The head of that fill plug isn't very tall, and for some stupid reason it's tapered in towards the end. Many, many have been rounded off with a 12-point socket that's hard to get on there square. Same thing if you try an impact. Replacements are not expensive, I would suggest you have one on hand before you dive in. Heating it up carefully with a propane torch does seem to help. Penetrating oil is useless, as under that flange there's a rubber seal.... So the oil can't get to the threads.
If it's been on there forever and never changed and you round off the head, it only takes a minute to weld an old socket onto it. (1/2 drive preferably, then you can break it loose easy) If you don't have a welder, most shops will quickly spot weld a socket on for you for a nominal fee.

Drain plug is easy. No issues with those.

@rdezs awesome thank you for the info, I’m a welder by trade so it’s at least comforting to know there’s a way out lol

 

[West 1]

When I change the tranny fluid I drop the pan and install a new filter. I do not have a lift so this is done with the truck up on jack stands. So far I have been able to slip the tranny pan out by using a truckers strap with the ratchet to tighten. I wrap one end around the exhaust pipe and anchor to the jack stand. The other end with the ratchet is also anchored to the jack stand. Then it is easy to slowly crank down the exhaust pipe by tightening the ratchet a few cranks. You can watch the pipe move and see when you might have enough room to slip the pan out. Tightening the exhaust pipe down to the jack stand does nothing to the safety of the truck on the stands, 25% or more of the truck weight is sitting on the jack stand so it is solid. This way you can work with both hands on removal and on install of the tranny pan which helps as you are trying to install that pan in a tight area while keeping the new gasket in place. I have done it this way 4 or 5 times now. Works for me. Just be smart where you attach to the exhaust pipe so you get good leverage pulling it down.

 

[West 1]

On the tranny fill cap, good advice to make sure it comes loose before draining. I would start with a 6 point socket. If yours is stuck a 6 point might break it loose while a 12 point might strip the plug and then you are welding and buying a new plug. I have only found one that was stuck and it was a bear to get out. I welded a large nut to the cap to get mine out but a socket if you have one to waste would sure work well.

 

[swathdiver]

Sorry for the third post in 3 days, my other truck is a 2019 Ram so this truck is very new to me and I want it to last. I have a 6L80 transmission 6.2 and I’m wondering what temp it should be running at? Is it different on hot days in New England? Today it’s over 100 degrees and it ran between 185 and 190 on a half hour or so ride. It generally seems to shift very well but I had to pull out quick today and have it gas pretty hard and it took right off but seemed to take kind of a hard shift. Is this something I should worry about or fairly normal? I just put the plug in AFM delete in today 20 minutes before this if that helps

Normal. The fluid can get up near 400 degrees. The DIC will start getting your attention after 260 degrees. If mine got that hot, I'd change it soon after.

On your run, it wasn't long enough for it to cool down below that.