2007 denali 145K...trans flush or no?

[11bravo]

My Denali trans is okay, sometimes a very slight quick-shift form 2-3 on a light throttle, but most always just smooth shifts up and down. Fluid is still pink, but with a slight tan to it. I was considering a trans flush versus just doing my own fluid change, but a shop I called recommended against the flush due to miles on the trans. Do any of you have hard evidence against the flush with my mileage?

If I do it myself, I will do two changes a couple hundred miles apart, and change the filter on the second change. Cost is not an issue for flush versus doing the change myself..

Thoughts?

 

[Foggy]

Don't "flush". Just service it normally. Filter, Clean pan, new fluid.
If it makes you feel better, just do it again in a couple of months or so...
Always drop the pan. Clean up everything. New Filter & Fluid...
Just changing the fluid only does very little

 

[petethepug]

No flushy. The slip is the warning sign on 07-08 trans. You wouldn’t want to dislodge anything into the system at that milage.

For giggles and kicks shop around for a 2019+ 10L80 10speed trans. If you source one from a running known good / crashed truck, plop that in and begin the ear to ear grin.

Home - Powertrain Swap Solutions

www.powertrainswapsolutions.com

https://static.nhtsa.gov/odi/tsbs/2014/SB-10043845-3346.pdf

 

[donjetman]

Change it.
When we bought our 07 Denali in 2018 it had been road had for 130k miles. Fluid looked bad.

I pulled the tranny out to do a rear main seal job. While tranny was out I changed all 12 qts of atf because I change the torque converter too.

Today at 200k miles it working good still

 

[Marky Dissod]

Don't "flush", just service it normally. Filter, clean pan, new fluid.
If it makes you feel better, just do it again in a couple of months or so ...
Always drop the pan. Clean up everything. New Filter & Fluid ...
Just changing the fluid only does very little.

I THINK a different version of what he's trying to say, is to
drop the pan and change the filter more often
more often than the manual says under 'severe service'.

 

[petethepug]

No on the flushy, yes on a typical fluid & filter change as Foggy said.

Your 6L80 exhibits the symptoms of cracks in the shift housing as well as the shift flare.

Be mindful of investing in labor, parts and fluid you’re going to be due for shortly (again). The trans is already at the tail end of its service life.

When the 6L80 in our 08 had the same symptoms I bought an 09 to get e85, no peel pearl paint, no crack leather dash and a/c seats. The Esky was $2.5k more than what the YXL Denali sold for with the same 140k milage.

You’re choices are:

* Do nothing
* Prep for it by getting bids.
* Prep more buying new OEM motor mounts, front diff, ARP exh mani bolts.
* Buy, sell or trade for another w/o AFM (07/08/09).

Going from an 08 to an 09 prolonged my trans replacement for another 3 years. This was back in 2020. Your milage is low buddy.

 

[donjetman]

@11bravo
Here is a discussion with used atf analysis reports:
https://www.tahoeyukonforum.com/threads/atf-lab-results-dexron-vi-43k-miles-on-fluid.134360/

 

[Rick10Tahoe]

I’ve got 2010 Tahoe I bought new. Now with 172k miles on original transmission (and lifters). I always have dealer do a flush every 50k miles and going great. Again, still on original transmission!

 

[petethepug]

Pay now (with recommended timely flush) or pay later with the other way …

 

[Campie]

No flushy. The slip is the warning sign on 07-08 trans. You wouldn’t want to dislodge anything into the system at that milage.

For giggles and kicks shop around for a 2019+ 10L80 10speed trans. If you source one from a running known good / crashed truck, plop that in and begin the ear to ear grin.

Home - Powertrain Swap Solutions

www.powertrainswapsolutions.com

https://static.nhtsa.gov/odi/tsbs/2014/SB-10043845-3346.pdf

Any thoughts on a PO989-00 code? 2007 Yukon Denali 6.2 with 6 speed tranny. 160k miles. No noticeable performance issues at this time.

 

[swathdiver]

Any thoughts on a PO989-00 code? 2007 Yukon Denali 6.2 with 6 speed tranny. 160k miles. No noticeable performance issues at this time.

 

[Campie]

View attachment 466727

Oh nice, so if I’m reading this correctly, this is what it SHOULD be reading as when I’ve looked at it I’m in park. Or am I NOT reading this correctly and I have the beginnings of a problem?

 

[swathdiver]

Oh nice, so if I’m reading this correctly, this is what it SHOULD be reading as when I’ve looked at it I’m in park. Or am I NOT reading this correctly and I have the beginnings of a problem?

I read it as you probably have dirty fluid and if it keeps happening you may need to overhaul the TECHM and or Valve Body. This can be done without removing the transmission from the vehicle.

Let's ask Nick, I just stayed at the Holiday Inn Express last night: @NickTransmissions

 

[Campie]

I read it as you probably have dirty fluid and if it keeps happening you may need to overhaul the TECHM and or Valve Body. This can be done without removing the transmission from the vehicle.

Let's ask Nick, I just stayed at the Holiday Inn Express last night: @NickTransmissions

I kind of wondered about the transmission fluid quality myself. We had a full flush, drop the pan, change the filter in 2023, and the car only has 11,000 miles on it since then. It’s at the shop now to get the oil pan dropped and cleaned, the oil pick up tube O-ring replaced and the crankshaft sensor replaced. We’ve asked them to check the transmission fluid because of that code.

 

[DoubleDingo]

Older thread, but I wouldn't hesitate to do a series of drain and fills and replace the filter. Just did it on my new-to-me 2005 Tahoe with 155k. It was darker than I was comfortable with, so I swapped out 3 gallons on Sunday. I couldn't do the filter, need to go somewhere with the Tahoe, but the fluid is red now, and when we get back I'll do two or three more drain and fills and change the filter on the last one while the pan is empty(extractor pump being used to drain). It shifts better, and seems to engage better as well.

 

[Campie]

Older thread, but I wouldn't hesitate to do a series of drain and fills and replace the filter. Just did it on my new-to-me 2005 Tahoe with 155k. It was darker than I was comfortable with, so I swapped out 3 gallons on Sunday. I couldn't do the filter, need to go somewhere with the Tahoe, but the fluid is red now, and when we get back I'll do two or three more drain and fills and change the filter on the last one while the pan is empty(extractor pump being used to drain). It shifts better, and seems to engage better as well.

Right! We couldn’t do the filter/pan ourselves but could change the fluid a couple times. Thanks for the idea!

 

[rdezs]

I converted my OEM rubber transmission cooler lines to AN6, using 3/8 compression fittings to adapt to the OEM pipes. Then an AN6 adapter to the radiator. (And an inline hydraulic filter on the return line)

Once a year, I disconnect the AN fitting on the return line, and connect a clear 6 foot hose to it, with an AN fitting ....start vehicle until I get 4 quarts out. Then add 4 qts. Repeat 4 times. Every other year I dropped the pan and replaced that filter, but it's always totally clean. Not even any dust at the bottom of the pan. That in line filter is doing wonders.

Almost 180,000 miles and the fluid has always looked excellent. With a complete fluid change every 12,000 miles roughly, hoping this transmission will outlive the entire vehicle....

 

[Campie]

I converted my OEM rubber transmission cooler lines to AN6, using 3/8 compression fittings to adapt to the OEM pipes. Then an AN6 adapter to the radiator. (And an inline hydraulic filter on the return line)

Once a year, I disconnect the AN fitting on the return line, and connect a clear 6 foot hose to it, with an AN fitting ....start vehicle until I get 4 quarts out. Then add 4 qts. Repeat 4 times. Every other year I dropped the pan and replaced that filter, but it's always totally clean. Not even any dust at the bottom of the pan. That in line filter is doing wonders.

View attachment 467560View attachment 467561

Almost 180,000 miles and the fluid has always looked excellent. With a complete fluid change every 12,000 miles roughly, hoping this transmission will outlive the entire vehicle....

Wow, that is an awesome upgrade! Unfortunately, our poor baby will have to be satisfied with getting a full change/pan drop every year. He doesn’t have to work very much but when he does, he has to pull a camper so I guess he deserves a bit of extra love!