10 speed Transmission Hot - Please help

[truckguy82]

Was randomly browsing this topic. Haven’t posted in years. I was one of the first people to have this issue about 9 years ago on my 2014 6.2L with the 6l80. I had to troubleshoot it myself. Same symptoms, temp just kept rising.

 

If you want to know if your trans thermostat is stuck, all you have to do is locate the lines to the trans cooler, you can follow the 2 lines off the trans.

 

If the thermostat is operating normally, both the supply and return to the cooler will be scolding hot, if the line is stuck closed (which I believe still allows a very small amount of flow) then the supply line to the cooler will be hot, and the return will be cool to the touch because your trans cooler will have cooled the fluid to ambient because the flow is so slow.

 

Cliff notes:

when trans is fully warmed up….

thermostat ok = trans fluid line return line from cooler is hot

Malfunction = return line is cool to the touch

 

for reference, the k2xx trucks trans thermostat didn’t open until 190 degrees. With the trans cooler functioning normally, I could drag race while towing 6k lbs and it never got above 205.

 

260+ is really high and I’d replace all that fluid.

Edited August 29 by truckguy82

[ArthurW]

On 8/29/2024 at 12:23 AM, truckguy82 said:

Was randomly browsing this topic. Haven’t posted in years. I was one of the first people to have this issue about 9 years ago on my 2014 6.2L with the 6l80. I had to troubleshoot it myself. Same symptoms, temp just kept rising.

 

If you want to know if your trans thermostat is stuck, all you have to do is locate the lines to the trans cooler, you can follow the 2 lines off the trans.

 

If the thermostat is operating normally, both the supply and return to the cooler will be scolding hot, if the line is stuck closed (which I believe still allows a very small amount of flow) then the supply line to the cooler will be hot, and the return will be cool to the touch because your trans cooler will have cooled the fluid to ambient because the flow is so slow.

 

Cliff notes:

when trans is fully warmed up….

thermostat ok = trans fluid line return line from cooler is hot

Malfunction = return line is cool to the touch

 

for reference, the k2xx trucks trans thermostat didn’t open until 190 degrees. With the trans cooler functioning normally, I could drag race while towing 6k lbs and it never got above 205.

 

260+ is really high and I’d replace all that fluid.

Little delayed in getting back to you - but thank you for the information.

I will double check this next time I have the truck hot. For reference - it would be fairly easy for me to overheat my transmission if I was to "drag race" my truck while towing. I watch these videos of people towing, putting the pedal to the floor while climbing a mountain to see how it holds speed, etc. My truck's transmission would overheat in 10 minutes if I did that lol.

I have a shutter now while driving at highway speeds, (kind of intermittently) and a few real weird shifts/flares at times. Unfortunately all of these issues are very intermittent, and I know my dealer would "not able to replicate" it lol. 

[Ejl923]

Had my first real tow with my 24 5.3/ 10 spd Silverado.  Towed my 4000 lb camper  340 miles, mid August.  Temp didn’t get much above 170 the entire trip.  Other than a malfunctioning part, wonder if there were any changes between the two years?

[truckguy82]

On 9/12/2024 at 3:17 PM, ArthurW said:

Little delayed in getting back to you - but thank you for the information.

I will double check this next time I have the truck hot. For reference - it would be fairly easy for me to overheat my transmission if I was to "drag race" my truck while towing. I watch these videos of people towing, putting the pedal to the floor while climbing a mountain to see how it holds speed, etc. My truck's transmission would overheat in 10 minutes if I did that lol.

I have a shutter now while driving at highway speeds, (kind of intermittently) and a few real weird shifts/flares at times. Unfortunately all of these issues are very intermittent, and I know my dealer would "not able to replicate" it lol. 

Yeah mine would get to 230 degrees just not towing anything.

 

It literally was just a slow and gradual rise up to temp like it’s supposed to, but it just didn’t stop rising. Exactly what would happen if you didn’t have a functioning trans cooler because the flow was blocked.

 

Back when I had a problem with mine, the dealer could not figure it out and nobody had ever had this problem before. Had to diagnose on my own. It seems relatively common now. I bet 75% of people don’t even look at their trans temp and most would have no idea.

 

I’d just remove the thermostat if you can. Our was at 190 degrees so I didn’t remove mine because I didn’t think it was wise to run at like 60 degrees less than design temp in the winter. But now that you guys have a 150-160 degree stat, it proves that 190 is BS…I would just remove it. In the case of the 6l80, it was just called “flipping the pill” which was basically just making sure the thermostat was always open. Thermostat was external though. Not sure how easy it is on the 10speed’s.

Edited September 13 by truckguy82

[TheRiver]

Can't hardly believe the OP has put up with this for a YEAR now!!!!!!!

[ArthurW]

On 9/13/2024 at 5:29 PM, truckguy82 said:

Yeah mine would get to 230 degrees just not towing anything.

 

It literally was just a slow and gradual rise up to temp like it’s supposed to, but it just didn’t stop rising. Exactly what would happen if you didn’t have a functioning trans cooler because the flow was blocked.

 

Back when I had a problem with mine, the dealer could not figure it out and nobody had ever had this problem before. Had to diagnose on my own. It seems relatively common now. I bet 75% of people don’t even look at their trans temp and most would have no idea.

 

I’d just remove the thermostat if you can. Our was at 190 degrees so I didn’t remove mine because I didn’t think it was wise to run at like 60 degrees less than design temp in the winter. But now that you guys have a 150-160 degree stat, it proves that 190 is BS…I would just remove it. In the case of the 6l80, it was just called “flipping the pill” which was basically just making sure the thermostat was always open. Thermostat was external though. Not sure how easy it is on the 10speed’s.

Unfortunately it is part of the valve body on the 10 speeds with the gas application. Probably explains the reluctance on GM's part to do anything to help me. 

I have very similar symptoms to what you had though. Temperature just continuously goes up, never comes down. 

 

On 9/15/2024 at 5:55 AM, TheRiver said:

Can't hardly believe the OP has put up with this for a YEAR now!!!!!!!

I've basically given up on it at this point. After 12 visits to the dealer, countless headaches, phone calls with GM Support Canada, and countless emails, a meeting with the general manager of my local dealer, a meeting with a service manager at another dealer, I have literally gotten NOWHERE. 

I really like GM's trucks otherwise, but the dealers around me aren't willing to do anything to help me. I've just come to the conclusion that I will trade the truck in when it makes sense financially, and never come back to GM again because of this whole ordeal. I don't even care that the truck has issues, the problem I have is that it's been a ridiculous headache trying to get some layer of service to help me with the issue. I won't buy another GM. From my experience where I live, and with the lack of support on my local dealer's, and GM Canada's part there is no way I can risk having to go through this again with another vehicle. 

 

It is what it is, but it's a shame that someone who's been an avid GM guy for years has just been let down this heavily. This issue will affect my families purchases, and most of my social and professional work environments purchases moving forward who all know about the issues I've had. All over a call it maximum $5000.00 repair. 

 

Edited October 10 by ArthurW

[TrueBlue]

Personally Arthur, I don't understand GM's position on this. That $5K repair might have equaled the profit they made on the truck. Maybe. But even if it did it would have been a wash. Now they're getting to keep their profit on this one rig, and lose many potential sales and profits on other vehicles as a result. I'm not a businessman but I don't see how that equates to sustainability of their bottom line.

[truckguy82]

On 10/10/2024 at 9:32 AM, ArthurW said:

Unfortunately it is part of the valve body on the 10 speeds with the gas application. Probably explains the reluctance on GM's part to do anything to help me. 

I have very similar symptoms to what you had though. Temperature just continuously goes up, never comes down. 

 

I've basically given up on it at this point. After 12 visits to the dealer, countless headaches, phone calls with GM Support Canada, and countless emails, a meeting with the general manager of my local dealer, a meeting with a service manager at another dealer, I have literally gotten NOWHERE. 

I really like GM's trucks otherwise, but the dealers around me aren't willing to do anything to help me. I've just come to the conclusion that I will trade the truck in when it makes sense financially, and never come back to GM again because of this whole ordeal. I don't even care that the truck has issues, the problem I have is that it's been a ridiculous headache trying to get some layer of service to help me with the issue. I won't buy another GM. From my experience where I live, and with the lack of support on my local dealer's, and GM Canada's part there is no way I can risk having to go through this again with another vehicle. 

 

It is what it is, but it's a shame that someone who's been an avid GM guy for years has just been let down this heavily. This issue will affect my families purchases, and most of my social and professional work environments purchases moving forward who all know about the issues I've had. All over a call it maximum $5000.00 repair. 

 

Here’s how you can prove it and what I would do.

 

Get a laser thermometer off amazon or home depot, cheap one, take a video, upload it to youtube so you can easily share it. In the video, show the trans temp on the dash, and then show the temp of both of the external trans cooler lines with the laser thermometer.

 

If your thermostat is like the 6l80’s, it will still allow for 5-10% flow. That means the line to the trans cooler will be scorching hot. Because the flow is so slow the output line of the trans cooler will get cooled down to ambient. If it’s zero flow both lines will be cool.

 

This is undeniable evidence that you don’t actually have a problem with your trans and that you just don’t have any trans cooler flow.

 

If you want you can email it to me and I can throw it on my youtube. I use youtube just to easily store and share personal videos.

Edited October 11 by truckguy82

[ArthurW]

On 10/11/2024 at 10:34 AM, truckguy82 said:

Here’s how you can prove it and what I would do.

 

Get a laser thermometer off amazon or home depot, cheap one, take a video, upload it to youtube so you can easily share it. In the video, show the trans temp on the dash, and then show the temp of both of the external trans cooler lines with the laser thermometer.

 

If your thermostat is like the 6l80’s, it will still allow for 5-10% flow. That means the line to the trans cooler will be scorching hot. Because the flow is so slow the output line of the trans cooler will get cooled down to ambient. If it’s zero flow both lines will be cool.

 

This is undeniable evidence that you don’t actually have a problem with your trans and that you just don’t have any trans cooler flow.

 

If you want you can email it to me and I can throw it on my youtube. I use youtube just to easily store and share personal videos.

On 5/26/2024 at 1:55 PM, ArthurW said:

 

 

I have some videos of the same process, both in front of the truck at the cooler and also underneath.

 

Been down this road unfortunately.

[truckguy82]

3 hours ago, ArthurW said:

 

I have some videos of the same process, both in front of the truck at the cooler and also underneath.

 

Been down this road unfortunately.

Was that with the trans hot?

 

really depends where you measured. Most accurate place is the lines.

 

But yeah, looks like it’s definitely not working. Wish i could help.

Edited October 13 by truckguy82

[ArthurW]

2 hours ago, truckguy82 said:

Was that with the trans hot?

 

really depends where you measured. Most accurate place is the lines.

 

But yeah, looks like it’s definitely not working. Wish i could help.

Yeah that was with the transmission over 100c I believe. I have a video showing all the temps, pan was like 119 I think, lines near pan were 90s, and lines near cooler were 30 and 20