Trans fluid flow direction for 6L80E

[dkad260]

Before I make a mess, i forgot which cooler line at the radiator is in and out. I assume it enters through the bottom of the radiator and leaves through the top?

 

[Foggy]

Before I make a mess, i forgot which cooler line at the radiator is in and out. I assume it enters through the bottom of the radiator and leaves through the top?

Common sense would dictate that hot enters into the top and then it cools as
it gets lower with the lower line returning the "cooler" fluid back to the trans...
I marked mine a couple years ago when i added a cooler.. But I'm not near the
yukon now to check

 

[dkad260]

Common sense would dictate that hot enters into the top and then it cools as
it gets lower with the lower line returning the "cooler" fluid back to the trans

That's what I was thinking but after a few searches I found some posts on the fluid going from bottom to top...which is why asked in the manner I did.

 

[dkad260]

After some more looking, I believe the bottom to top was the GMT800.

 

[mikez71]

I feel like when I did a fluid flush, that I removed the upper line to pump fluid out of radiator..
But my memory is 50/50...

If you have an external cooler, I believe it should go through radiator first?

Here it is...

6l80 Transmission Cooler Line Diagram & Flow Direction

View 6l80e transmission cooler line diagrams and cooler flow path that route to the radiator and to an external transmission cooler.

transmissioncoolerguide.com

Could be botton to top bleeds air bubbles better?

 

[dkad260]

I feel like when I did a fluid flush, that I removed the upper line to pump fluid out of radiator..
But my memory is 50/50...

Same...it was almost 50K ago and I'm overdue for at least a pan drop. I believe it was the top line but I wanted to be sure before I spray fluid everywhere...lol.

I think it was the upper line that I attacked a hose to.

 

[rdezs]

From the transmission it enters the lower part of the radiator tank, exits at the upper fitting on the tank and is routed to the auxiliary transmission cooler, then return to the transmission.

If in doubt follow the lower fitting on the transmission.... That's the return line.

 

[dkad260]

To play it safe, I hooked a hose up to the line that enters the top of the radiator, and also a hose coupler for the port in the radiator.

The fluid exited the top port of the radiator.

The fluid is darker than I expected but does not smell burnt in any way...still not a welcoming sight.