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6L80e fluid return line #4486204
08/11/17 11:44 PM
08/11/17 11:44 PM
Joined: Aug 2005
Posts: 152
Northern Nevada
cb4017 Offline OP
cb4017  Offline OP
Joined: Aug 2005
Posts: 152
Northern Nevada
My Jeep JK Wrangler now has a GM LS 5.3L engine and a 6L80 transmission. I'm upgrading the tranny fluid cooler and want to make sure I have things flowing the right way. Which line is the fluid return line, top or bottom at the transmission? I thought it was the top line but found some conflicting information on the interweb.

Thanks!


Cliff
USN Ret., FPD Ret.
Re: 6L80e fluid return line [Re: cb4017] #4486208
08/11/17 11:52 PM
08/11/17 11:52 PM
Joined: Jun 2003
Posts: 17,479
Deplorable in apple valley, ca
Chris142 Offline
Chris142  Offline
Joined: Jun 2003
Posts: 17,479
Deplorable in apple valley, ca
Take one off and have someone start it,and be ready to turn it off.


02 Wrangler durablend 10w40
87 F250 traveler 15w40
04 Tahoe super-s 10w30
Z400 castrol T 10w40
Can am maveric edge 5w40
57 case tractor 15w40
Re: 6L80e fluid return line [Re: cb4017] #4486214
08/12/17 12:06 AM
08/12/17 12:06 AM
Joined: Jun 2003
Posts: 2,724
BC, Canada
userfriendly Offline
userfriendly  Offline
Joined: Jun 2003
Posts: 2,724
BC, Canada
Bottom line from transmission to top of rad, return line is from bottom of rad to top of transmission.

Re: 6L80e fluid return line [Re: userfriendly] #4486235
08/12/17 12:45 AM
08/12/17 12:45 AM
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Merkava_4 Offline
Merkava_4  Offline
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Originally Posted By: userfriendly
Bottom line from transmission to top of rad, return line is from bottom of rad to top of transmission.


That makes good sense. It would be easier for the fluid to flow down through the radiator--rather than flow upwards.

Re: 6L80e fluid return line [Re: Merkava_4] #4486244
08/12/17 01:12 AM
08/12/17 01:12 AM
Joined: Aug 2005
Posts: 152
Northern Nevada
cb4017 Offline OP
cb4017  Offline OP
Joined: Aug 2005
Posts: 152
Northern Nevada
Originally Posted By: Merkava_4
Originally Posted By: userfriendly
Bottom line from transmission to top of rad, return line is from bottom of rad to top of transmission.


That makes good sense. It would be easier for the fluid to flow down through the radiator--rather than flow upwards.


Hmm, B&M says the input should be on the bottom on their Supercoolers if the connections are on the side. Seems fill from the bottom would ensure the cooler is filled where top feed maybe not. Come to think of it I guess it would depend on the type cooler. Tube and fin wouldn't matter where on a stack plate cooler it might.


Cliff
USN Ret., FPD Ret.
Re: 6L80e fluid return line [Re: userfriendly] #4486250
08/12/17 02:05 AM
08/12/17 02:05 AM
Joined: Dec 2013
Posts: 2,281
Fort Worth, Texas
clinebarger Online content
clinebarger  Online Content
Joined: Dec 2013
Posts: 2,281
Fort Worth, Texas
Originally Posted By: userfriendly
Bottom line from transmission to top of rad, return line is from bottom of rad to top of transmission.


The cooler feed/out is the TOP cooler line, The BOTTOM line is the return/lube on a 6L80E WHERE they come out of the bellhousing.


2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/Auto
Re: 6L80e fluid return line [Re: cb4017] #4486254
08/12/17 02:37 AM
08/12/17 02:37 AM
Joined: Jun 2003
Posts: 2,724
BC, Canada
userfriendly Offline
userfriendly  Offline
Joined: Jun 2003
Posts: 2,724
BC, Canada
Me bad, I do T350s & 400s bottom feed to cooler "in" at top of rad, bottom of rad return to top line on transmission.

Re: 6L80e fluid return line [Re: userfriendly] #4486255
08/12/17 02:47 AM
08/12/17 02:47 AM
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Merkava_4 Offline
Merkava_4  Offline
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Now you guys got me all kinds of confused. ???

Re: 6L80e fluid return line [Re: Merkava_4] #4486272
08/12/17 04:30 AM
08/12/17 04:30 AM
Joined: Jan 2011
Posts: 2,748
N.Ohio
Lubener Offline
Lubener  Offline
Joined: Jan 2011
Posts: 2,748
N.Ohio
Originally Posted By: Merkava_4
Originally Posted By: userfriendly
Bottom line from transmission to top of rad, return line is from bottom of rad to top of transmission.


That makes good sense. It would be easier for the fluid to flow down through the radiator--rather than flow upwards.


Usually the bottom of the radiator cooler is the inlet. You want the fluid in the cooler longer so the heat is transfered. If it flows too quickly(from top to bottom), the transfer of heat is minimized. On my Buick, the bottom line was the fluid source into the radiator cooler.Not to be confused with the coolant which has far less pressure behind it.

Last edited by Lubener; 08/12/17 04:35 AM.

The "thinking" man's friend.
Re: 6L80e fluid return line [Re: cb4017] #4486282
08/12/17 05:50 AM
08/12/17 05:50 AM
Joined: Jun 2003
Posts: 2,724
BC, Canada
userfriendly Offline
userfriendly  Offline
Joined: Jun 2003
Posts: 2,724
BC, Canada
I just R&R'd a couple of T350s 'n 400s a month ago. Before pulling them, I disconnected the top line from the radiator, put a hose on the end into a 5L oil jug and started the engines.
I got about 3 liters out that way, which otherwise would have ended up on the ground or driveway.
If in doubt, take both lines off with hoses into containers.

Re: 6L80e fluid return line [Re: cb4017] #4486293
08/12/17 06:14 AM
08/12/17 06:14 AM
Joined: Nov 2006
Posts: 20,106
MA, Mittelfranken.de
Trav Offline
Trav  Offline
Joined: Nov 2006
Posts: 20,106
MA, Mittelfranken.de
Find the line on the transmission from this slightly outdated chart and follow it to the radiator if in doubt.


ASE L1, Master. Deutsch Meisterbrief.
Re: 6L80e fluid return line [Re: cb4017] #4486373
08/12/17 08:37 AM
08/12/17 08:37 AM
Joined: Dec 2013
Posts: 2,098
socal
barkingspider Offline
barkingspider  Offline
Joined: Dec 2013
Posts: 2,098
socal
Fluid goes into the cooler on the bottom and out from the top on the GM trucks I've owned. 6.0, 5.3 and 4.8


06 Cadillac Escalade Ext
17 Cadillac ATS (wife)
05 Toyota Camry (daughter)
11 GMC Canyon off-road (daily)
Re: 6L80e fluid return line [Re: Trav] #4486435
08/12/17 09:48 AM
08/12/17 09:48 AM
Joined: Aug 2005
Posts: 152
Northern Nevada
cb4017 Offline OP
cb4017  Offline OP
Joined: Aug 2005
Posts: 152
Northern Nevada
Originally Posted By: Trav
Find the line on the transmission from this slightly outdated chart and follow it to the radiator if in doubt.


I found this chart. I also found others that indicated the opposite, hence my confusion. Guess I'm going to have to pull a line and do the bucket test. If it matters my transmission is supposed to be a 2013.


Cliff
USN Ret., FPD Ret.
Re: 6L80e fluid return line [Re: cb4017] #4487857
08/13/17 09:03 PM
08/13/17 09:03 PM
Joined: Dec 2013
Posts: 2,281
Fort Worth, Texas
clinebarger Online content
clinebarger  Online Content
Joined: Dec 2013
Posts: 2,281
Fort Worth, Texas
#8, Cooler Feed (Fluid OUT to cooler) Top line at the transmission.
#9, Center Lube (Fluid RETURN from cooler) Bottom line at the transmission.

I checked a 6L80E GM service manual & a 6L80E ATSG manual, Same picture in both!

All GM/Hydramatic RWD units are this way with the exception of the TH200 & 200-4R which are backwards.
Late 4L80E's have Front & Rear cooler lines, Front is feed, Rear is return.




Last edited by clinebarger; 08/13/17 09:03 PM.

2001 Chevy Camaro L92/4L80E
2006 Chevy 2500HD LBZ/Allison 1000
2010 Toyota Corolla 2ZR-FE/Auto
Re: 6L80e fluid return line [Re: cb4017] #4488798
08/14/17 10:17 PM
08/14/17 10:17 PM
Joined: Aug 2005
Posts: 152
Northern Nevada
cb4017 Offline OP
cb4017  Offline OP
Joined: Aug 2005
Posts: 152
Northern Nevada
Awesome! Thank You Sir.


Cliff
USN Ret., FPD Ret.

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