6L80E Trans Trouble

My apologies for any duplication but am on my phone, away from home so searching is pretty hard.
The 6L80E in my 13 Yukon XL RWD is acting up and I'm debating trying to slap together so thing to make it back home or just run it. The truck doesn't have the HD cooling package so I only have the rad mounted cooler. It gets hot (205+) in stop and go traffic and starts to bang into 1st and feel really sluggish and jerky in 1-3. The temp just keeps climbing when not on the constant move. The hotter it gets, the worse it feels. Fluid was at the bottom of the cold mark before we left town and I put half a quart in it.

The kludge would be to put some Napa HD cooler lines and whatever trans cooler they have in stock to try and keep it cool on the way home which is mostly open back roads at 70mph. Does fine at around 185 in 90-95 deg weather locked up in 6th gear, it's just when I got into traffic close to the destination that it started to heat up and slip.

Advice?

IMO fluid temp is not your problem. My 197k mile 07 Denali has the factory rpo code KNP trans cooler setup and gets up to 200+*f occasionally when it gets hot driving in TX, NM, etc.
I send used dexron6 atf samples off for analysis and as a result I do a dump and fill every 25k miles and also a filter change every 50k miles.
I did change my torque converter at 130k miles. The torque converter is a known weak link and can take out the tranny.

@NickTransmissions

CTX-SLPR said:

... 6L80E in my 13 Yukon XL RWD is acting up and I'm debating trying to slap together something to make it back home or just run it.
The truck doesn't have the HD cooling package so I only have the rad mounted cooler.
It gets hot (+205F) in stop and go traffic and starts to bang into 1st and feel really sluggish and jerky in 1-3.
The temp just keeps climbing when not on the constant move. The hotter it gets, the worse it feels.
Fluid was at the bottom of the cold mark before we left town and I put half a quart in it.

Click to expand...

Central Texas? Certainly for now, you REALLY don't need the radiator mounted heat exchanger.
It's NOT a cooler, if anything it's an ATF warmer / heater. It effectively shares some engine heat with the ATF.
It brings ATF up to operating temp sooner, especially for COLD winters. (If you don't have cold winters, no need for it at all, just drive gently for the first five minutes.)
It also increases 'normal' ATF temps to eke out another MpG or 2 or 3 for CAFE MpG test purposes.

For now, if you can find a way to safely bypass the radiator's ATF heat exchanger, ATF won't run as hot.

Another thing you can do is get the ecm & tcm tuned for lower fan-on threshold temps, among several other things that be programmed into the tcm to eke out a bit more life from the 6L80.

But yea, you'll likely need
@NickTransmissions
counsel for this one.

CTX-SLPR said:

My apologies for any duplication but am on my phone, away from home so searching is pretty hard.
The 6L80E in my 13 Yukon XL RWD is acting up and I'm debating trying to slap together so thing to make it back home or just run it. The truck doesn't have the HD cooling package so I only have the rad mounted cooler. It gets hot (205+) in stop and go traffic and starts to bang into 1st and feel really sluggish and jerky in 1-3. The temp just keeps climbing when not on the constant move. The hotter it gets, the worse it feels. Fluid was at the bottom of the cold mark before we left town and I put half a quart in it.

The kludge would be to put some Napa HD cooler lines and whatever trans cooler they have in stock to try and keep it cool on the way home which is mostly open back roads at 70mph. Does fine at around 185 in 90-95 deg weather locked up in 6th gear, it's just when I got into traffic close to the destination that it started to heat up and slip.

Advice?

Click to expand...

just limp it home if you haven't already, sounds like it is toast already all you are saving is the price of a tow instead

CTX-SLPR said:

My apologies for any duplication but am on my phone, away from home so searching is pretty hard.
The 6L80E in my 13 Yukon XL RWD is acting up and I'm debating trying to slap together so thing to make it back home or just run it. The truck doesn't have the HD cooling package so I only have the rad mounted cooler. It gets hot (205+) in stop and go traffic and starts to bang into 1st and feel really sluggish and jerky in 1-3. The temp just keeps climbing when not on the constant move. The hotter it gets, the worse it feels. Fluid was at the bottom of the cold mark before we left town and I put half a quart in it.

The kludge would be to put some Napa HD cooler lines and whatever trans cooler they have in stock to try and keep it cool on the way home which is mostly open back roads at 70mph. Does fine at around 185 in 90-95 deg weather locked up in 6th gear, it's just when I got into traffic close to the destination that it started to heat up and slip.

Advice?

Click to expand...

Sounds like 3-5-R drum and torque converter are beginning to wear/fail...3-5-R drum leaks at the base welds, short-circuiting clutch life...Not sure where you or the vehicle is at now but it's time for a rebuild.

Check out my 6L80 Information Thread for more details (link is in my signature).

Thanks to all the responses. I did read the entire (well skipped the argument part) 6L80E info thread last night and was able to cross some of my symptoms to it and did some checking this morning. I made it home safely with no issues on the way but that doesn't mean I trust it...

Luckily, I was visiting my parents and best friend who also wrenches on his own stuff. We pulled the pan and the fluid looked good, not too much clutch material in it and I had to get my finger dipped in the fluid right up to the light to even see a hint of sparkles, like maybe 6 pinpoints of glitter on my whole fingertip. I noticed the trans, bellhousing, and pan where all painted grey, in my mind the trans and bell should be bare aluminum but no idea on the new stuff. Put a Duralast filter and Valvoline MaxLife Dex VI into it and did a test drive. It still gets hotter than I'd like (~200ºF in stop and go traffic) but I noticed a +10ºF offset between the pan sensor and grill ambient sensor so I suspect the real fluid temp is lower. It runs fine and other than the occasional clunk on the 2-1 downshift at a light it's fine. My friend hooked up his Autel scan tool and poked around but didn't see anything. Shift speeds were consistent across the temperature range when compared to throttle input. He did see noticeable temperature spikes in stop and go traffic when accelerating but that seems pretty normal.

I'm planning on calling Circle D tomorrow since I'm only about 1hr away and talking it over with them. I'm leaning towards a reman where I'll pull my current unit and use one of my other vehicles to exchange and do the swap on a Thursday - Sunday sometime in the future. I'll ask for general upgrades per the info thread in line with being behind a stock 6.2L as I'm not going crazy but getting 6.0-6.2L power sounds appealing as it's a bit weaker than I'd like towing, might just be the 3.08 gears. Also do the cooler lines to the KND setup with the 40K cooler. Finally, I have HP Tuners so going to mess with the fan curve, the shift speeds/pressures, and the TCC per the info thread.

Thanks again for the responses!

200 is normal for stop and go city driving in the summer heat.

swathdiver said:

200F is normal for stop and go city driving in the summer heat.

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Used to drive a 2012 Yukon XL as a livery driver for six and seven figure people in NYC.
Stuck in Manhattan rush hour traffic on a 99F day, hottest ATF temp I've EVER seen was 212F.
Typically the reported ATF was between 194F & 203F. Over 203F, it was a VERY HOT DAY.
(Acceptable, but cooler would have been preferable.)
Those temps had nothing to do with towing, hauling, or any intense driving of any kind -
most of my clients preferred gentle driving.
My Yukon XL only had 3.08 axles, no Tow/Haul package or any other additional cooling accoutrements, just the basics.

It may be hotter than I'd like but I can concede that it might just be the way things are now and with the 10ºF bias on the readback it could be OK. What I'm struggling with is the slipping and banging into 1st that came with the higher temps. If I drove this vehicle around town as my daily (which I don't anymore) I'd probably be more easy but instead I'm taking students or scouts around in it. I don't think a fluid change on a trans that didn't look bad gives me the confidence to do that.

I've called around and used the online quote tool for Street Smart. Choices seem to be
1. GM reman for $6600 installed with a 3yr warrantee
2. Jasper reman for $6900 installed with a 3yr warrantee
3. Street Smart Reman for $3700 installed with a 5yr parts warrantee but $50/hr labor rate
4. Semicustom Circle D rebuild for $7200ish installed with a 2yr warrantee but with some level of parts selection

None of this includes a cooler but I can take care of that even before they get ahold of the vehicle. I saw Street Smart recommended on the info thread and their reviews look pretty good but knowing this thing is already on trans #2 (confirmed the original should have been raw not painted) I'm worried again about it letting my passengers down on a trip to West TX hauling the troop trailer even if it is under warrantee.