Transmission overheating?

Brummie99 · March 16, 2020

I took a trip this weekend, about 450 mile round trip, towing a lightly loaded flat utility trailer (maybe 2,500lbs overall).

Maybe 50 miles into the trip, I noticed it was maintaining high revs and reluctant to change to higher gears. As if it were in tow/haul mode (but it wasn't).

On the outbound leg, transmission temp was hovering in the mid to high 90's. On the return trip, things started off OK but then started again. Trans temp peaked at 208 degrees and wouldn't hit top gear. Ambient temp was around 85 degrees.

Truck has just passed 60,000 miles. I've done about 10,000 miles of that.

Could it just be time for a trans fluid change or something more serious?

TIA

Chris

ETA: It's the 6.0 gas engine.

Edited March 16, 2020 by Brummie99

CamGTP · March 17, 2020

If you asked GM, 190-210 on the transmission temps would be considered normal.

Changing the fluid at 60,000 miles in not a bad idea and installing an aftermarket cooler is never a bad idea either if you tow a decent amount.

What are you going through doesn't seem that odd to me though. We have a GMC box truck at my work with the 6.0/6L90e combo under the hood. The truck is about 8-9,000lbs dry and we load several thousand pounds into it on the regular. When at speed and even on somewhat level ground it tends to downshift into 5th gear and just hold it for really long periods of time. Any minor hill and it's 5th all the time.

Z45 · March 17, 2020

fyi...............................

In the February 2011 issue of Trailer Life magazine RV Clinic in response to a reader about the maximum transmission temperature allowed in a 2009 Chevy Silverado, the Tech Team had this response.

“General Motors’ in-house towing team expert provided RV Clinic with this statement: The maximum allowable automatic transmission fluid temperature is dictated by the transmission oil itself. The oil begins to degrade significantly above 270 degrees Fahrenheit, so we design vehicles so that in all but the most extreme conditions, the fluid temperature in the transmission sump stays below 270 degrees F.

We allow for up to 285 degrees F in extreme conditions (i.e. towing a trailer with combination loaded at GCWR in Death Valley). But for customer usage anywhere else in the country, even at GCWR, transmission sump temperature should stay well below 270 degrees F. Above this point, certain internal components, such as seals, begin to disintegrate rather quickly. Although newer synthetic fluids can withstand higher temperatures we still recommend this (270F) as a maximum temperature. "

Brummie99 · March 17, 2020

OK. So, don't be too focused on those temperatures.

I still feel that with the relatively light load, it should have been shifting better. Even on a long downhill stretch, it wouldn't move to top gear. Maybe the trailer brakes were binding. Not my trailer so don't know it's history.

I pulled my 10,000lb travel trailer 1200 miles a few of months ago and it seemed to tow better than this one.

I'll get the transmission fluid and filter changed and see how it goes next trip.

Thanks for the feedback.

JD110 · March 28, 2020

I had same problem, torque converter clutch was bad. 2017 with 30,000 miles. No check engine light, had p0741stored.

Brummie99 · May 10, 2020

On ‎3‎/‎28‎/‎2020 at 12:17 PM, JD110 said:

I had same problem, torque converter clutch was bad. 2017 with 30,000 miles. No check engine light, had p0741stored.

What did the repair cost?

I took our first long trip yesterday since getting the transmission fluid/filter changed.

Towing a small 5x8 enclosed U-Haul trailer. Was fine for the first 40+ miles, then started acting up again. By the time we reached our destination, check engine light was on. Pulled codes P0700 & P0741. I reset the codes and headed home later in the afternoon. Again, ran for 50+ miles OK. When we hit some traffic lights, it reverted back again. Max trans temp was about 180 degrees for the whole trip.

I haven't done a long trip without a trailer for some time but I suspect it would be the same solo.

FYI: I towed my 10,000lb travel trailer 450 miles in November without a problem, so this is definitely a new problem.

Grumpy Bear · May 10, 2020

1 hour ago, Brummie99 said:

What did the repair cost?

I took our first long trip yesterday since getting the transmission fluid/filter changed.

Towing a small 5x8 enclosed U-Haul trailer. Was fine for the first 40+ miles, then started acting up again. By the time we reached our destination, check engine light was on. Pulled codes P0700 & P0741. I reset the codes and headed home later in the afternoon. Again, ran for 50+ miles OK. When we hit some traffic lights, it reverted back again. Max trans temp was about 180 degrees for the whole trip.

I haven't done a long trip without a trailer for some time but I suspect it would be the same solo.

FYI: I towed my 10,000lb travel trailer 450 miles in November without a problem, so this is definitely a new problem.

What the P0741 code means. The Powertrain Control Module (PCM) will set the P0741 diagnostic trouble code when it notices a difference between the rotational speed of the torque converter and the transmission input shaft that is greater than 200 revolutions per minute (RPM).

JD110 · May 10, 2020

Torque converter was replaced under warranty. It did not damage trans. I tow 10,000 lbs. trailer also, but it happened while not towing. Works good now.

Edited May 10, 2020 by JD110
Missing word

Brummie99 · May 11, 2020

9 hours ago, Grumpy Bear said:

What the P0741 code means. The Powertrain Control Module (PCM) will set the P0741 diagnostic trouble code when it notices a difference between the rotational speed of the torque converter and the transmission input shaft that is greater than 200 revolutions per minute (RPM).

Yeah. It throws the error if this occurs twice within one journey. Explains why I'm only seeing it on longer trips. My daily routine is 11 miles each way in town to work so no real opportunity for it to register other than on longer trips.

9 hours ago, JD110 said:

Torque converter was replaced under warranty. It did not damage trans. I tow 10,000 lbs. trailer also, but it happened while not towing. Works good now.

Pretty sure it's unrelated to towing. My last two longer trips when this occurred were both towing.

I need to find a reliable transmission shop to get it checked.

Brummie99 · May 18, 2020

So, took it to a local shop recommended by a colleague who has used them several times in the past.

I told them:

1. Symptoms as described in this thread.

2. It had given error P0741 but I had cleared it on my last trip and it had not thrown the error again even though it was still acting up.

3. The problem only occurs on longer trips

4. I'd had the transmission fluid and filter changed 3-4 weeks ago.

They kept it for 3 days. At the end of day 1, called and they said they would get to it first thing the next day.

At the end of day 2, they said they had driven it but couldn't find anything wrong. OK. I had cleared the error during the prior trip but I told them that and also that it only occurred on longer trips. They said they would drop the pan and check for anything in there (presumably looking for broken pieces).

Well, according to the MyGMC app, my truck hasn't moved from their lot since I dropped it off Wednesday morning.

Lunchtime on day 3, I talked to the colleague that recommended them. When he called them, they repeated their line about dropping the pan. He mentioned to them about the GPS tracker. (they didn't respond).

I picked it up on Friday evening. They said they couldn't find anything wrong but suggested replacing the converter/solenoid package for around $1500.

The only positive I can say is they didn't charge me.

I reviewed the dashcam footage when I got home. They didn't even look at it until after my colleague called them on Friday. It was on the lift for about 75 minutes. My camera only records while ignition is on so didn't see what they did other than checking the transmission fluid level.

I think my next step is to take it on a long run until it starts acting up and then drive it directly to the dealership.

03 Cobra · June 4, 2020

Brummie, interesting story and I'm subscribing because I have a 2015 6.0. Good luck to you with your tranny, hope it comes out ok in the end. No problems yet for me but I am just starting to tow with it so I'll keep an eye on things.

Second question, can you spill the beans on the dash cam set up you have? What a great tool for checking on things like dealerships and other situations when your truck is not right under your thumb. I am a newbie to dash cams so please speak slowly and write with crayons :)!!

Thanks.

Brummie99 · June 4, 2020

I took the truck for a long-ish drive a couple of weeks ago. No trailer but trying hard to 'cause' a problem by hard accelerating frequently. The plan was to create the error and drive directly to the dealer so they would see first hand.

No dice. It behaved perfectly. I don't have any towing planned for a while, just nervous if (when) I hook up my fifth wheel I won't get far. We're heading into hurricane season down here in FL so may need to evacuate at short notice.

The camera is a Rexing V1 4K I bought from Amazon. I've had it for 2 years and still working even in the FL summer heat. Just replaced the SD card as it was starting to fail. Also, getting the GPS adapter for it this week. I have it tied into the truck 12v power so it comes on with the ignition. It's also available with a secondary rear (wired) camera. Make sure to get a high-endurance SD card as regular cards won't last as long as the high-endurance ones.

03 Cobra · June 4, 2020

Don't you love those problems that you can't reproduce on demand?! Let's hope it was a fluke and that it's gone for good.

High five on the camera information and the links to Amazon!! You got me really thinking about one. Will have to read up on it but might just be a Father's Day prez for myself this year!!