Keeping coolant and transmission temps under control when towing in the summer heat

[Geotrash]

If you think about it.. the trans fluid goes thru a nice cool radiator first and can
shed A LOT of heat initially... until the T-Stat open up it's pretty cool up there.
So it really takes a bit to get the trans temp UP... And in winter/cold it helps
stabilize the temps so you don't run too cool

Yes, and it occurred to me that the transmission cooler is on the downstream side of the radiator where the water temperature will be coolest before heading back into the engine.

 

[mikeyss]

I got these pictures in stop and go traffic. I will go up the mountain tomorrow. Highest my trans got was 145 today and it was 97 degrees out. My fans did kick on to HI 2 or 3 times though. I also had the A/C blasting.
I didn't hook up my tech2 to check engine temp, but the dummy gauge stayed at the normal center spot it always is at

 

[Geotrash]

I got these pictures in stop and go traffic. I will go up the mountain tomorrow. Highest my trans got was 145 today and it was 97 degrees out. My fans did kick on to HI 2 or 3 times though. I also had the A/C blasting.
I didn't hook up my tech2 to check engine temp, but the dummy gauge stayed at the normal center spot it always is at

View attachment 281059

Awesome! Thanks for the data points.

We pulled the camper to the beach yesterday and the transmission temp never got above 203°, and only then after I had to floor it for a while to get on the highway in front of a truck. Coolant temp stayed at 195°. That 6.2 really hauls.


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[Geotrash]

The trip home was a different story. Much hotter weather, still pulling the camper. My ambient temperature sensor has been relocated to a better place and always reads between 2-3º of ambient air temp as reported by my Apple Watch . Anyway, ambient temp according to the truck (full sun on the highway) was high 90s for most of the trip, with a few peaks into 100-101ºF. We were on I-64 westbound between Norfolk and Richmond and the transmission temp hovered around 207ºF with the coolant temp staying around 210ºF. We hit some stop and go traffic and the transmission would peak around 215ºF once we got going and I saw the coolant hit 230ºF a couple of times on some longer grades at 65-70 mph. We pulled off the highway to get to the house and the transmission temp peaked at 232ºF with all of the traffic lights, while the engine coolant dropped to around 200ºF. By the time we got to the house the transmission had settled to around 225ºF

Net/Net, the transmission stays cool on the highway until it has to do a lot of shifting in traffic (to be expected), and there is a time lag of 5 minutes between pulling off the highway, and maximum transmission temp in traffic before it starts to come down again. The coolant runs a little warm on the highway until I get off and it cools down quickly. I'm not getting the cooling from the Derale I was hoping for. It's less effective than the Tru-Cool was.

Next steps: 1/ Fix the baffles beside the radiator permanently with some coroplast. When I got home I noticed my temporary repair had failed, so that should help the coolant temps on the highway. 2/ Fab up some deflectors from sheet aluminum to increase ram airflow to the Derale, since it's mounted behind the license plate. I also noticed that the Derale fan started making some noise, so I will investigate that as well.

The weekend after next, I'll be running the same road that saw my transmission temp hit 265ºF before I rerouted the transmission cooler lines through the radiator. We'll see if plumbing the radiator cooler back into the system really does anything to shave off those higher temp spikes.

Gotta get this thing 100% dialed in before mid August when we hit the road for Yellowstone and the Tetons.

 

[03_GMC]

Great information. Have you thought about moving your license plate down like I did on mine? That alone will allow much more airflow. Since installing my new cooler I haven’t seen the trans get higher than 187. I haven’t towed anything yet though. We leave in less than 48 hrs. for Yellowstone so I will have plenty of info to pass along.


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[gooffeyguy]

My ambient temperature sensor has been relocated to a better place and [bold]ALWAYS[/bold] reads between 2-3º of ambient air temp as reported by my Apple Watch .

Where did you mount your Apple Watch, or do you just always ride with your arm out the window [emoji848][emoji23]

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[Geotrash]

Where did you mount your Apple Watch, or do you just always ride with your arm out the window [emoji848][emoji23]

LOL! Maybe THAT'S why my A/C never came off high fan for the whole trip!

 

[Geotrash]

Great information. Have you thought about moving your license plate down like I did on mine? That alone will allow much more airflow. Since installing my new cooler I haven’t seen the trans get higher than 187. I haven’t towed anything yet though. We leave in less than 48 hrs. for Yellowstone so I will have plenty of info to pass along.

That's a great idea. Maybe I will try that first. Or move it to the side to keep my ground clearance, since I do wheel this truck sometimes.

Looking forward to hearing about your experiences on your trip!

 

[03_GMC]

That's a great ides. Maybe I will try that first. Or move it to the side to keep my ground clearance, since I do wheel this truck sometimes.

Looking forward to hearing about your experiences on your trip!

I just bent mine back to contour the bumper. It doesn’t hang any lower than the bumper valance.


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[mikeyss]

I only made it up to Carter Lake, which is a semi challenge for vehicles but nowhere near as difficult as some other places here in the Front Range. I did get some elevation with 20mph speeds in 95 degree weather. Trans got up to 152 and engine temp was in it's normal range. Engine fans only ran HI twice that I could hear. I will get a mountain run here soon.