Ordering correct transmission cooler lines

[2011TXDenali]

I need to replace the transmission cooler lines on my 2011 Yukon Denali since they are starting to leak. When I go to look up the part, it gives two options of with or without Heavy Duty Transmission Cooling Package (KNP). How would I know if my Yukon does or doesn't have that?

Thanks in advance! Pic of the mess below.

 

[donjetman]

I have KNP trans cooling package and GM# 25999420 and 15779543 is what I put on mine.

 

[OR VietVet]

The KNP trans cooling package info would be at the RPO codes inside the glove compartment. Then you can look up the correct application for your rig.

 

[Foggy]

Yes.. Look at the codes on the sticker in your glovebox...
Also, that really looks like engine oil mess to me... Might just be the
how the pic is taken.. You have engine oil cooler lines as well.
They start out near the oil filter at the block and go to the DRIVERS side of the
radiator. Your trans lines are on the PASSENGER SIDE of the radiator

 

[swathdiver]

I need to replace the transmission cooler lines on my 2011 Yukon Denali since they are starting to leak.

If you have an external transmission cooler you need these two:

15779543 and 25999420

if you do not have the external transmission oil cooler you need this one:

25999418

A frequent source of transmission failure is reduced flow in the lines and cooler. GM tests for this to determine if the flow rate is within spec. Consider replacing the cooler if you pull the bumper cover to do this work. 20880895

 

[2011TXDenali]

Yes.. Look at the codes on the sticker in your glovebox...
Also, that really looks like engine oil mess to me... Might just be the
how the pic is taken.. You have engine oil cooler lines as well.
They start out near the oil filter at the block and go to the DRIVERS side of the
radiator. Your trans lines are on the PASSENGER SIDE of the radiator

This pic was from the passenger side. Those are the transmission lines that you see there. I replaced the engine oil cooler lines a few months ago. But it is a big mess.

 

[2011TXDenali]

Thanks everyone for the tip about the codes in the glovebox!

 

[Rocket Man]

(

Thanks everyone for the tip about the codes in the glovebox!

Those are called the Regular Production Order or RPO codes and contain all the information concerning the options and specs on your truck. There are RPO code lists you can download and decipher them. I always take a pic of mine, print it out and keep it handy. It’s useful when ordering parts.

 

[donjetman]

This pic was from the passenger side. Those are the transmission lines that you see there. I replaced the engine oil cooler lines a few months ago. But it is a big mess.

Looks like engine oil to me too.
Hope it's not rear main seal and/or cover. I had to replace mine.
Also could be from oil filter, oil cooler line adapter plate, valley cover between the heads and under the intake manifold, valve cover, oil pressure sending unit.

 

[slowride77]

Hi All-

This thread came up on a search i ran here for transmission cooler lines. I have the standard return line leak that i see is common out there.
I am trying to find the torque spec for the bolt that holds the block that attaches the two lines to the driver's side of the transmission.
I have seen a few youtube videos that claim it is 18 lb-ft, but they were using the size of the bolt to determine that from what i could tell.
Anyone out there verify that or have the actual spec?

Also, any tips or tricks when replacing these line sets would be great!

 

[swathdiver]

Hi All-

This thread came up on a search i ran here for transmission cooler lines. I have the standard return line leak that i see is common out there.
I am trying to find the torque spec for the bolt that holds the block that attaches the two lines to the driver's side of the transmission.
I have seen a few youtube videos that claim it is 18 lb-ft, but they were using the size of the bolt to determine that from what i could tell.
Anyone out there verify that or have the actual spec?

Also, any tips or tricks when replacing these line sets would be great!

16 foot pounds.

Remove the differential carrier mounting nuts (75 ft lbs) and washers allowing it to hang down some. Remove the bolts (37 ft lbs) from the bottom of the strut. That will give enough room to fish the lines out and in.

I use a Lisle 22930 to remove the lines from the cooler and radiator.

 

[slowride77]

16 foot pounds.

Remove the differential carrier mounting nuts (75 ft lbs) and washers allowing it to hang down some. Remove the bolts (37 ft lbs) from the bottom of the strut. That will give enough room to fish the lines out and in.

I use a Lisle 22930 to remove the lines from the cooler and radiator.

I have the 22930 Lisle tool. Thanks for the torque spec.

Any pics or exploded views of the parts you are referring to?

 

[swathdiver]

It's not letting me copy and paste.

 

[Geotrash]

16 foot pounds.

Remove the differential carrier mounting nuts (75 ft lbs) and washers allowing it to hang down some. Remove the bolts (37 ft lbs) from the bottom of the strut. That will give enough room to fish the lines out and in.

I use a Lisle 22930 to remove the lines from the cooler and radiator.

James, do you think this same technique would work for the oil cooler lines as well?

 

[swathdiver]

James, do you think this same technique would work for the oil cooler lines as well?

Yes, I had forgotten that we loosened the bolts on the driver's side differential and let it hang low. We also were replacing the engine mount with an H3 mount. Did not have to mess with the strut on the driver's side.

 

[slowride77]

16 foot pounds.

Remove the differential carrier mounting nuts (75 ft lbs) and washers allowing it to hang down some. Remove the bolts (37 ft lbs) from the bottom of the strut. That will give enough room to fish the lines out and in.

I use a Lisle 22930 to remove the lines from the cooler and radiator.

I found this video on YouTube. I believe this is what you are referring to at the 12 min mark.

Diff carrier nuts

 

[swathdiver]

I found this video on YouTube. I believe this is what you are referring to at the 12 min mark.

Diff carrier nuts

Yep, that's it.

 

[thauglor1119]

Hi all, instead of creating a new thread I figured just keep adding to this one as it was one of the first results in search.

I have a 2011 LT with the KNP code, only 1 line is leaking, but this is part of the two line set in part number 25999420. Can anyone confirm that I do not need 15779543 as well?

I think the 1577 line goes from the radiator cooler (top line) to the aux cooler, is that correct?

Thanks!

Drivers side looking towards passenger side

 

[OR VietVet]

@thauglor1119, welcome to the forum from Oregon.

You should start your own thread about your lines and truck. You will get more responses that way.

I don't think a mod can pluck your one response to another thread and you should start your own.

 

[mikez71]

yep the 1577 is the short line.