Maintenance: Transmission Flush

[Shimmy23]

Hey Guys,

I could use some help... I've been watching DIYers here:

I realize this is for a denali but the second link should be appropriate and I'm still not getting it!

and

https://www.gmfullsize.com/threads/how-to-4l60e-transmission-flush-filter-change.179148/

Is the transmission line different for a 2008 Yukon? When I loosen the "trans cooler line" a lot of fluid comes out and it isn't ATF fluid. Its antifreeze!

Which line should I be unscrewing to flush the fluid?

 

[HiHoeSilver]

Hey Guys,

I could use some help... I've been watching DIYers here:

I realize this is for a denali but the second link should be appropriate and I'm still not getting it!

and

https://www.gmfullsize.com/threads/how-to-4l60e-transmission-flush-filter-change.179148/

Is the transmission line different for a 2008 Yukon? When I loosen the "trans cooler line" a lot of fluid comes out and it isn't ATF fluid. Its antifreeze!

Which line should I be unscrewing to flush the fluid?

Take a pic of what you got. You probably have the snap in line. I'm guessing you're unscrewing the bulkhead for the fitting, hence the coolant coming out.

 

[Shimmy23]

Here's the area i'm trying to loosen

 

[HiHoeSilver]

Here's the area i'm trying to loosen

Don't loosen that. Pop the little clip off (be careful, it's gonna want to fly away) and the line will pull right out. Then use this :

Hayden Automotive 397 Transmission Line Fitting Kit https://www.amazon.com/dp/B000EPRCAC/ref=cm_sw_r_cp_apa_O8MRBbZQNNJ0B

 

[Shimmy23]

Don't loosen that. Pop the little clip off (be careful, it's gonna want to fly away) and the line will pull right out. Then use this :

Hayden Automotive 397 Transmission Line Fitting Kit https://www.amazon.com/dp/B000EPRCAC/ref=cm_sw_r_cp_apa_O8MRBbZQNNJ0B

Thanks for the link and tip but I’m still confused here. When I undo that line antifreeze is coming out... not ATF.

So boggled right now. Yuk has 66k miles on it. Why am I getting antifreeze out of this line? Is that even possible? Fluid has never been flushed and I’ve owned her since new.

 

[HiHoeSilver]

Thanks for the link and tip but I’m still confused here. When I undo that line antifreeze is coming out... not ATF.

So boggled right now. Yuk has 66k miles on it. Why am I getting antifreeze out of this line? Is that even possible? Fluid has never been flushed and I’ve owned her since new.

Take a picture of what you're doing. That's the right line.

 

[gooffeyguy]

The side tank of the radiator has a brass or copper "inner tank" that the trans fluid runs into. The antifreeze surrounding the inner tank helps cool it.

2001 Yukon SLT
2012 Yukon XL Denali
2011 Yukon Denali RIP 5/20/18

Sent from my SM-G930V using Tapatalk

 

[Shimmy23]

Take a picture of what you're doing. That's the right line.

Right! That’s why my head is spinning. I loosened the line (circled in my above post) and fluid started coming out. I read that minimal ATF may come out so I kept unscrewing it. Then I noticed the smell really smelled like antifreeze. I stopped and looked at the rag I had placed below the area (to catch any small amount of fluid) and it was soaked with antifreeze. Thinking I was going crazy I opened the new bottle of ATF and compared the fluids and sure as shit antifreeze was the fluid coming out of that connection.
I verified again that it was antifreeze since a puddle of it had now drizzled onto the garage floor.

A part of me wants to try and remove the line again but (still thinking I’m going crazy here) why would I expect a different result this time. I think if I pull the line out the antifreeze is gonna pour out and cause a royal mess

 

[HiHoeSilver]

Right! That’s why my head is spinning. I loosened the line (circled in my above post) and fluid started coming out. I read that minimal ATF may come out so I kept unscrewing it. Then I noticed the smell really smelled like antifreeze. I stopped and looked at the rag I had placed below the area (to catch any small amount of fluid) and it was soaked with antifreeze. Thinking I was going crazy I opened the new bottle of ATF and compared the fluids and sure as shit antifreeze was the fluid coming out of that connection.
I verified again that it was antifreeze since a puddle of it had now drizzled onto the garage floor.

A part of me wants to try and remove the line again but (still thinking I’m going crazy here) why would I expect a different result this time. I think if I pull the line out I’m gonna get antifreeze gushing out.

No, you won't. By unscrewing that bulkhead, you're not seeing what's in the line, you're seeing what's in the radiator surrounding the line. Make sense? Pop that C clip off instead and pull the line out leaving the bulkhead (and the coolant) in place. You will need something like the adapter I posted to put where the line goes so you have something to put your tube onto.

 

[Shimmy23]

No, you won't. By unscrewing that bulkhead, you're not seeing what's in the line, you're seeing what's in the radiator surrounding the line. Make sense? Pop that C clip off instead and pull the line out leaving the bulkhead (and the coolant) in place. You will need something like the adapter I posted to put where the line goes so you have something to put your tube onto.

I'm unscrewing the trans oil cooler fitting, as shown below. You're saying that if i remove the e-clip and pull the line out, i'll get a different fluid? How so? unscrewing vs unclipping the line should yield the same results.



I agree that your suggestion is easier. I don't understand how unclipping it will change the result of my getting this damn antifreeze. Thanks again for helping! You're probably thinking, "this dudes an idiot!"