10 speed Transmission Hot - Please help

GETGONE · September 23, 2023

13 hours ago, Naughty Donkey Performance said:

Have you installed this? wondering if there is any measurable amount of fluid loss during the install.

I haven't. I haven't had any issues with hot trans temps. Someone posted this somewhere so I saved it for future reference.

ArthurW · September 27, 2023

On 9/21/2023 at 2:42 AM, GETGONE said:

Probably not something you want to do since it's under warranty, but this is an option:

https://www.thoroughbreddiesel.com/125069000/

Appreciate the thought, but this only works for the 3.0 Duramax. The thermal bypass valve on the 10L80 attached to the 5.3 is internal to the transmission and would entail replacement of the valve body I believe.

As an update to this whole ordeal, I took the camper out again last weekend and the transmission overheated again. This time went to 132C (270F) before setting off the alarm for "Hot transmission - idle engine".

It went back to the dealership, who took it for a test drive, was unable to replicate the issue, checked for twisted lines (none found), updated the TCM, and noticed the transmission was down 1L of fluid and gave it back to me saying it's good to go.

While I doubt this is fixed, I will take my trailer for a drive this weekend, but fully expect it to overheat again. 1L on a 11-12liter capacity 10L80 would not cause the transmission to go nuclear this quickly. I'm guessing there's either a blockage, or the bypass valve internally is faulty.

As far as the GM post above, they emailed me back and supposedly are acting as a mediator between the dealership and myself. We'll see if it goes anywhere, but as of yet I haven't heard from anyone.

GETGONE · September 27, 2023

3 hours ago, ArthurW said:

Appreciate the thought, but this only works for the 3.0 Duramax. The thermal bypass valve on the 10L80 attached to the 5.3 is internal to the transmission and would entail replacement of the valve body I believe.

It says it's for ALL 10L80 transmissions:

PPE Transmission Oil Thermal Bypass Valve - 2020-2023 GM Duramax 3.0L LM2/LZ0 | 2018-2022 GM 1500 V6 & V8 (Equipped with 10L80 Transmission)

ArthurW · September 27, 2023

2 hours ago, GETGONE said:

It says it's for ALL 10L80 transmissions:

PPE Transmission Oil Thermal Bypass Valve - 2020-2023 GM Duramax 3.0L LM2/LZ0 | 2018-2022 GM 1500 V6 & V8 (Equipped with 10L80 Transmission)

You may be right, I was thinking that this actually attached to the thermal bypass, maybe you can bypass it from the outside of the transmission. My original thought came from the bulletin from GM:

"The Thermal Bypass Valve (TBV) may be the cause of the overheat if a cooler line is not twisted or misshaped. The TBV will open at the following temperatures for the models listed in this TSB. 6 Speed (6L80, 6L90) - 158F (70C) - TBV is external to the transmission. 8 Speed (8L90) - 194F (90C) – TBV is external to the transmission. 10 Speed (10L80, 10L90, 10L1000) – 143F (61C) – TBV is within the valve body on all listed applications except those equipped with 3.0 (LM2) Diesel. On the LM2 Diesel, the TBV is external to the transmission."

Good call, I will buy it if it'll cool down the transmission.

redwngr · September 27, 2023

Something's not right with that transmission.

I'd be (making?) letting the dealer/GM work thru making it right rather than doing self mods that might give them an excuse to wash their hands of it.

newdude · September 27, 2023

6 hours ago, ArthurW said:

Appreciate the thought, but this only works for the 3.0 Duramax. The thermal bypass valve on the 10L80 attached to the 5.3 is internal to the transmission and would entail replacement of the valve body I believe.

As an update to this whole ordeal, I took the camper out again last weekend and the transmission overheated again. This time went to 132C (270F) before setting off the alarm for "Hot transmission - idle engine".

It went back to the dealership, who took it for a test drive, was unable to replicate the issue, checked for twisted lines (none found), updated the TCM, and noticed the transmission was down 1L of fluid and gave it back to me saying it's good to go.

While I doubt this is fixed, I will take my trailer for a drive this weekend, but fully expect it to overheat again. 1L on a 11-12liter capacity 10L80 would not cause the transmission to go nuclear this quickly. I'm guessing there's either a blockage, or the bypass valve internally is faulty.

As far as the GM post above, they emailed me back and supposedly are acting as a mediator between the dealership and myself. We'll see if it goes anywhere, but as of yet I haven't heard from anyone.

If the lines aren't twisted, then they need to target the cooler and the valve body next.

3 hours ago, GETGONE said:

It says it's for ALL 10L80 transmissions:

PPE Transmission Oil Thermal Bypass Valve - 2020-2023 GM Duramax 3.0L LM2/LZ0 | 2018-2022 GM 1500 V6 & V8 (Equipped with 10L80 Transmission)

But its not. The TBV is internal to the valve body on the gas 10 speeds 2019-current.

Website CLEARLY states diesel 10 speed - Transmission Fluid Thermal Bypass Block - GM 3.0L Duramax 10L80 – Pacific Performance Engineering (ppepower.com)

kmeleon · September 28, 2023

Just posting my 2 cents. I have a 21 1500 Elevation with 5.3L 10spd & 4wd. I pull a 24' enclosed car trailer that with my car loaded is about 8500lbs. I've pulled it anywhere from 50-200 miles one way in temps around 90F and normally I see upper 150'sF in temp. When towing up steep highway inclines in PA I've seen around 170F, maybe 175F tops. What you're seeing is absolutely not normal. Somethings wrong.

ArthurW · September 28, 2023

11 hours ago, kmeleon said:

Just posting my 2 cents. I have a 21 1500 Elevation with 5.3L 10spd & 4wd. I pull a 24' enclosed car trailer that with my car loaded is about 8500lbs. I've pulled it anywhere from 50-200 miles one way in temps around 90F and normally I see upper 150'sF in temp. When towing up steep highway inclines in PA I've seen around 170F, maybe 175F tops. What you're seeing is absolutely not normal. Somethings wrong.

Thank you for this, this is exactly what I'm looking for so as I continue to argue with my dealer to get this resolved I have some comparable data.

18 hours ago, newdude said:

If the lines aren't twisted, then they need to target the cooler and the valve body next.

But its not. The TBV is internal to the valve body on the gas 10 speeds 2019-current.

Website CLEARLY states diesel 10 speed - Transmission Fluid Thermal Bypass Block - GM 3.0L Duramax 10L80 – Pacific Performance Engineering (ppepower.com)

Thanks, I was sure I saw that somewhere.

19 hours ago, redwngr said:

Something's not right with that transmission.

I'd be (making?) letting the dealer/GM work thru making it right rather than doing self mods that might give them an excuse to wash their hands of it.

Agreed, after some thought, I won't be touching it until they have it fixed.

redwngr · September 28, 2023

3 hours ago, ArthurW said:

Agreed, after some thought, I won't be touching it until they have it fixed.

After it's fixed, you may not need to do anything.

ArtWi · October 1, 2023

Just for a further update for anyone else that has this issue and needs to deal with their dealership.

The transmission overheated again yesterday towing my utility trailer on the highway. As expected, the 1 litre of fluid and a TCM update did nothing to solve my issue, so back to the dealership I go. Woohoo (sarcasm).

And to boot, I'm pretty sure the truck is clunking in the rear, probably the famous loose U bolts on the leaf springs. I'll get them to look at that too. Whenever I get this resolved, I'll be sure to post my findings here so that hopefully it saves someone else some time rather than wasting time with these dealerships. It's ridiculous how bad the service can be at times.

ArtWi · October 2, 2023

Update: dealer looked at it today, said they couldn't find anything wrong (AGAIN). Asked when I was going to pick it up, I told them I don't want to take it back until they've found a solution.

I have no interest in lying to these guys, I'm not sure why they're so hesitant to keep it and try to replicate the issue rather than spending 15 minutes on it, and shrugging their shoulders. I just want my truck to be reliable, it's got like 2000 miles on it lol

newdude · October 2, 2023

16 minutes ago, ArtWi said:

Update: dealer looked at it today, said they couldn't find anything wrong (AGAIN). Asked when I was going to pick it up, I told them I don't want to take it back until they've found a solution.

I have no interest in lying to these guys, I'm not sure why they're so hesitant to keep it and try to replicate the issue rather than spending 15 minutes on it, and shrugging their shoulders. I just want my truck to be reliable, it's got like 2000 miles on it lol

Drive it there with the trailer while its hot. How heavy is the trailer 2000-3000lbs?

Warning comes on at 265F for more than 5 seconds or something like that.

Edited October 2, 2023 by newdude

ArtWi · October 2, 2023

On 10/2/2023 at 5:37 PM, newdude said:

Drive it there with the trailer while its hot. How heavy is the trailer 2000-3000lbs?

Warning comes on at 265F for more than 5 seconds or something like that.

The last time it overheated yeah around 3000lbs with my utility trailer, the time before that probably around 6000lbs with my camper.

Just frustrating that I will have to take my time, and fuel to show them the issue on a fourth trip. There's really only a few things that can cause this that I'm aware of; transmission lines, cooler blockage, thermostat and bypass valve. I've shown them pictures and videos of the truck overheating/giving warning to idle.

I can't see what would change on a diagnostic front with them physically seeing the temperature gauge at 260F.

They're going to look at it again tomorrow, we'll see how it goes.

UPDATE:

Today after a call to the service advisor, and then a lengthy email to the service manager I was told they are ordering "parts for the transmission". They're not sure if it's going to fix it, and they didn't want to throw parts at it with the hope of it getting fixed (which I appreciate) but the plan of not doing anything wasn't going to sit well with me.

That being said, I'm not sure what specifically they ordered, so I'll be checking into that tomorrow. Whenever I have the new "parts" installed I'll clarify what they are, and if it fixed my issue.

Edit 2: After some back and fourth with the dealer, they claim to have ordered the valve body. We'll see if this is the fix. Will update.

Edited October 7, 2023 by ArtWi

Carlos Eduardo Silva · November 26, 2023

On 10/2/2023 at 5:49 PM, ArtWi said:

The last time it overheated yeah around 3000lbs with my utility trailer, the time before that probably around 6000lbs with my camper.

Just frustrating that I will have to take my time, and fuel to show them the issue on a fourth trip. There's really only a few things that can cause this that I'm aware of; transmission lines, cooler blockage, thermostat and bypass valve. I've shown them pictures and videos of the truck overheating/giving warning to idle.

I can't see what would change on a diagnostic front with them physically seeing the temperature gauge at 260F.

They're going to look at it again tomorrow, we'll see how it goes.

UPDATE:

Today after a call to the service advisor, and then a lengthy email to the service manager I was told they are ordering "parts for the transmission". They're not sure if it's going to fix it, and they didn't want to throw parts at it with the hope of it getting fixed (which I appreciate) but the plan of not doing anything wasn't going to sit well with me.

That being said, I'm not sure what specifically they ordered, so I'll be checking into that tomorrow. Whenever I have the new "parts" installed I'll clarify what they are, and if it fixed my issue.

Edit 2: After some back and fourth with the dealer, they claim to have ordered the valve body. We'll see if this is the fix. Will update.

Did it fix ?

ArthurW · December 20, 2023

On 11/26/2023 at 6:40 PM, Carlos Eduardo Silva said:

Did it fix ?

Hey, no. My dealership seems to be completely useless - I haven't been able to get them to do anything. For the last few months they were "waiting on parts" because supposedly they had ordered the valve body, and after a nasty email I sent to GM support the dealer contacted me saying they wanted to "put this thing to bed" and were going to look at it this week - they looked at it today and again couldn't find anything. So now, I'll definitely have to bring it to them overheating. This is ridiculous, I can't understand how a dealership can be this problematic. I spent a ton of money on this truck, and for them to have no solution to the problem is ridiculous. I'm taking the camper to another province at the end of the month, so I fully expect to overheat it multiple times on the way down there, and when I get back I'll have to bring it to them when it's overheating.

This may end up having to go to a lawyer, because I just want my truck to function properly. I even threw it out there that if they could buy it back, I would purchase a higher trim nicer truck from them, but obviously to no surprise it was ignored.

I guess we will see with the next visit, or I'll have to stop at a different city's dealership and see if they can figure this thing out, but if not I don't know what other option I have. We're at 5 visits for the same problem, and 10,000KM and still nothing has been done other than "topped up fluids".

It's not like I'm doing this for entertainment, I want to haul my camper without worrying about overheating the transmission and sitting on the side of the highway.

Sigh.