6L80 Heat Related Symptoms

[CTX-SLPR]

IF you have it already set up with HPT you should go thru your torque converter settings
and shift scheduling to get rid of some of the crazy crap gm did with those settings

Already done that including a reflash after I put a ZipKit in the VB. I smashed the screen on my tuning laptop and I've not fixed it or moved on yet as I have it setup on the bench for testing my Riviera swap out along with the Microsquirt trans controller.

 

[CTX-SLPR]

@NickTransmissions, do you think the VB is bad and the valves are binding and a new VB will fix it or the unknown reman TC is coming apart and it's a total clean and redo?

Thanks

 

[NickTransmissions]

Regardless I get shifting weirdness at around 195º. What are the likely culprits that start sticking with heat? Things are fine at lower temps like today a 1hr drive in the mid 50ºs and misting was fine with trans temps in the 140ºs. Yes, I'm a pretty relaxed driver but I bought this vs. a minivan because I need to tow and I can't keep it acting normal unloaded so no way I'm going to hitch something to it even with a 40k cooler in the nose. Something is getting hot and acting up and I'd rather try to troubleshoot it before throwing $3.5k at a reman Street Smart unit.

Assuming the above is a fair and accurate description of your current drivability symptoms, Im guessing you have a worn out pressure regulator valve, especially if the 'weird shifting' occurs at multiple points in the drive cycle once the vehicle and transmission reach operating temp.

@NickTransmissions, do you think the VB is bad and the valves are binding and a new VB will fix it or the unknown reman TC is coming apart and it's a total clean and redo?

Thanks

The TC can be playing a role but unless you have shuddering, it's not likely. Valve body may or may not be worn - impossible to say without vacuum testing it.

Have you taken it for a drive with a bidirectional scan tool and/or HP Tuners plugged in showing what's happening once the transmission and torque converter once the unit starts mis-behaving? Does the vehicle have any engine/engine management related or electrical issues?

 

[CTX-SLPR]

Not done a drive with the scanners hooked up since all the maintenance, just last summer when things got real bad for the first time. The shifting weirdness is largely related to decelerating to a stop, vehicle comes almost to a stop then the trans downshifts the final time resulting in it feeling like it's trying to push through the brakes for a moment. This happens not infrequently but not constantly when hot. The really unnerving one is when you let off the brakes from a stop and it revs then lurches into gear. This is much rarer in frequency but will happen for sure on a 15-20min drive in traffic if it's up to 195º+. All of this centers around lower gears, never had a problem in the upper gears even before doing the Zip Kit and finding a missing check ball.
Thinking about it, the decel issue could be the converter trying to stay locked too long (I have 3-6 gear TCC still on) as from memory it's worse under harder braking. The TCC is up in the pump section which I've not been through beyond watching an analog gauge under the wiper on a 20min drive test drive just before doing the Zip Kit.

 

[NickTransmissions]

The really unnerving one is when you let off the brakes from a stop and it revs then lurches into gear.

This sounds like torque converter to me; I believe the 8-speed units are/were doing this or similar behavior, causing accidents...IIRC, the basis of the class action suits pending against GM for those converters was the sudden onset of violent, back-breaking shifts.

I'd get it to a shop asap if you're not able to fully diagnose and, if necessary, yank it out (assuming it's not already there). I think the TC is in the process of failing but that's just speculation from someone that isn't there and no data...Meanwhile drop the pan if you haven't already done so and you're willing/able to - see if there's anything at the bottom.

 

[CTX-SLPR]

When I did the Zip Kit in the fall there was some friction material in the pan after only a few (<5) thousand miles on the fluid which was more than I expected. No metal sparklies but the magnet was slightly dirtier than the main pan.

I'll drive it carefully the few times I have to get to class and such till I can get my backup car back from the family I loaned it to while I fix the front main seal on their truck.

 

[TahoeFL2017]

if it takes 45 minutes for it to get that warmed up that's not all that bad or you just do not drive it that hard, before I added the tru-cool 40k and B&M deep pan I could have mine at 220 in about 5 minutes. now it tops out normally at 180, I can make it hit 190 if I push it in pretty hot weather light to light, anything beyond 190 takes something severe my version of severe is like trying to outrun the motorola block to block.
And if I drive like a sane person it stays anywhere from 145-165, hot idle in the summer is dead on 180

I'm hitting 220 degrees and even 230 in stop and go traffic, in 90 degree FL weather.

Should I be concerned if not towing?

I have the updated thermostat for the trans, but if my factory cooler is in my radiator, how can it stay any coler than the 210 degree radiator?

I never paid attention to my trans temps since 2018, but recently have because I put the updated trans thermostat ( bypass thingy, whatever it's called)

Is city driving ok at 230 degrees? Because after 30 minutes I can hit that temp with my AC running in traffic.

 

[Fless]

I'm hitting 220 degrees and even 230 in stop and go traffic, in 90 degree FL weather.

Should I be concerned if not towing?

I have the updated thermostat for the trans, but if my factory cooler is in my radiator, how can it stay any coler than the 210 degree radiator?

I never paid attention to my trans temps since 2018, but recently have because I put the updated trans thermostat ( bypass thingy, whatever it's called)

Is city driving ok at 230 degrees? Because after 30 minutes I can hit that temp with my AC running in traffic.

What year vehicle is this? This thread is in the 2007-2014 section.

 

[Doubeleive]

I'm hitting 220 degrees and even 230 in stop and go traffic, in 90 degree FL weather.

Should I be concerned if not towing?

I have the updated thermostat for the trans, but if my factory cooler is in my radiator, how can it stay any coler than the 210 degree radiator?

I never paid attention to my trans temps since 2018, but recently have because I put the updated trans thermostat ( bypass thingy, whatever it's called)

Is city driving ok at 230 degrees? Because after 30 minutes I can hit that temp with my AC running in traffic.

I personally would be concerned with those temps.
did you put in the oem replacement thermostat or did you use a complete bypass?
the oem one is supposed to drop it to 160 I think instead of 180
I took mine out (bypassed it entirely) added a trucool 40k and B&M deep pan and it hovers around 165 in the 2018.
I was hitting 220 just driving down the street basically previously, just the way I drive I don't baby it.

 

[TahoeFL2017]

What year vehicle is this? This thread is in the 2007-2014 section.

2017 - didn't know the thread was for those years.

I'm still wondering how the trans temp can EVER go below the radiator temps, if it's part of that system

T-stat would run it cool until the radiator temps came up to 210, then I'd be at 210 anyways -right?

 

[Fless]

2017 - didn't know the thread was for those years.

I'm still wondering how the trans temp can EVER go below the radiator temps, if it's part of that system

T-stat would run it cool until the radiator temps came up to 210, then I'd be at 210 anyways -right?

Probably best to stick with your post in the correct year, as there may be differences.

Overheating 6L80e

You're way over thinking this...Fluid is a much more efficient heat exchanger than air so by eliminating the fluid's travel through the radiator's internal transmission cooler, you've cut your cooling efficiency by at least 50% or so.... I'm hitting 230 occasionally in Florida stop and go...

www.tahoeyukonforum.com

 

[Foggy]

2017 - didn't know the thread was for those years.

I'm still wondering how the trans temp can EVER go below the radiator temps, if it's part of that system

T-stat would run it cool until the radiator temps came up to 210, then I'd be at 210 anyways -right?

Yes. The trans temp usually is lower than the coolant. The coolant in your radiator
is constantly PULLING Heat from the Trans Fluid and transferring it to the coolant
where your radiator/coolant/fan keep it in check
And you are probably NOT running at 210* unless you are in stop and go traffic
and/or very hot situations or have a poorly maintained cooling system.

 

[TahoeFL2017]

Yes. The trans temp usually is lower than the coolant. The coolant in your radiator
is constantly PULLING Heat from the Trans Fluid and transferring it to the coolant
where your radiator/coolant/fan keep it in check
And you are probably NOT running at 210* unless you are in stop and go traffic
and/or very hot situations or have a poorly maintained cooling system.

I just hit 244 driving lightly with the ac on, 88 degrees outside.

 

[Geotrash]

I just hit 244 driving lightly with the ac on, 88 degrees outside.

Definitely need a cooler on that thing

 

[j91z28d1]

2017 - didn't know the thread was for those years.

I'm still wondering how the trans temp can EVER go below the radiator temps, if it's part of that system

T-stat would run it cool until the radiator temps came up to 210, then I'd be at 210 anyways -right?

trannys cooler is in the cooled side of the radiator, after it exits the engine at 210 on the drivers side, the radiator drops the Temps down and that's side is where your trans cooler is. also the engine cooling system with the thermostat will basically bypass the radiator and just circle water around in it thru the heater core to keep the engine up to temp, as the radiator fans have to run all the time for the ac, it would over cool the engine if coolent run thru it at 100%. if you buy one of those thermal heat guns, you can test around didn't spots and find the Temps.

the engine coolent Temps sensor might be be in a different location on your newer LT engine, but our older ls it's in the cylinder head which is the hottest place. I've seen a very large difference in the temp at the cylinder head, to the cool side of the radiator.

 

[TahoeFL2017]

Definitely need a cooler on that thing

I put the thermal bypass on about 5 months ago, so this is the first time in warmer weather.

WTF do you think is causing 240 degrees now? Radiator issues maybe?

Crazy that it's this hot in city driving, I literally drove 20 minutes to Lowe's and just randomly checked it on the way home, and it's at 244.

Fluid looks normal, shifts fine. Might have been 240 all the way to Georgia a few weeks ago, didn't check it all day.

 

[Foggy]

I put the thermal bypass on about 5 months ago, so this is the first time in warmer weather.

WTF do you think is causing 240 degrees now? Radiator issues maybe?

Crazy that it's this hot in city driving, I literally drove 20 minutes to Lowe's and just randomly checked it on the way home, and it's at 244.

Fluid looks normal, shifts fine. Might have been 240 all the way to Georgia a few weeks ago, didn't check it all day.

I bet your fans aren't working correctly !!! OR you still have trapped air inthe
cooling system. Maybe try re burping the system again. And really observe
if the fans have LOW and HIGH speed. They should both come on at the same
time. First they come on on LOW speed, then if needed the HIGH kicks in
OR when the AC is on sitting still they should eventually come on HIGH

 

[j91z28d1]

is it possible the tranny line stat is backward?? I thought most just removed that thing.


you are taking tranny Temps not coolent Temps right?

 

[TahoeFL2017]

is it possible the tranny line stat is backward?? I thought most just removed that thing.


you are taking tranny Temps not coolent Temps right?

I'm starting to think the t-stat was either installed wrong, or is sticking, and I just didn't see high temps until it got hot recently.

It gets hot very slowly steadily, as if the fluid is just staying in the trans and never getting to the cooler.

It takes 30 minutes of driving in 80+ degrees to break 200 degrees, then slowly but surely hits 20, 230, 240

Definitely trans fluid, right on my display.

Shifts completely fine, doesn't slip, you'd never know anything without looking at the temp readout..

But - I think I smell a faint odor of anti-freeze, so this might be something amiss in my radiator - but engine temps are steady.

 

[B-train]

How long does it take to get the AT up to 200F?

Do you have a factory cooler, or any cooler installed?

Holy Cow! I just did over 3k miles round trip to ID and back with 3000 lbs in tow and never went over 160F with mountain driving. My 2008 doesn't have the trans thermostat, so I think that's the key. Flip the pill or eliminate it with older model year cooler lines. A trans doesn't need to be 200F on a regular basis.