First trip with the 25LB was good, trans was a little hot

[JPKflagstaff]

First trip with our 25LB was good. I have a 2016 GMC Canyon 4x4 crew cab, rated at 7000 towing capacity, 6000 GVW, with 12000 combined. I'm at the 6k for the truck and 4800 to 5000 (loaded)of a trailer my combined is around 11K CVW.
It was 4 hrs each way mostly flat, on the large highway I maintained speed at 55 to 60, outside temp was upper 70s. The truck did well, a little under powered, the tow haul mode makes the engine scream to much, was experimenting with tow haul and manual positioning(5th gear)to keep my rpms at 2000 to 2300.
My trans temp hit 210 degrees once going and once on the way home,with averages running temps 190 to 205. I called the dealer to see if this is normal and they said it was fine and with the radiator at the same temp. Yes I do have the factory tow pkg with extra trans cooler.
I dont like it getting that hot but its normal? hopefully when it gets in the upper 80's and 90's it doesn't get hotter, it shouldn't.
Oh by the way I averaged 11 mpg towing and usually average 19 to 20 my regular driving. Next trip will be in the mountains and we'll monitor the temp.
Thanks,
Jeff

[007matman]

Doesn't sound too bad to me.

[ImTravis]

You’re fine, I sometimes get the same temps in my Silverado when towing. Temp usually creeps up when in traffic I’ve noticed.

[DieselDrax]

Those temps are fine and these transmissions and the Dexron-VI fluid are meant to withstand higher temps than we're used to. The hot ATF warning won't be triggered until the trans temp reaches 270F.

Your trans temps will likely be similar to mine since you have a 2016 so we both have the 6-speed auto, my trans temps after pulling a hill can see 221F but on flat ground usually sees around 208F.

[JPKflagstaff]

It’s nice to hear others have similar temperatures in there transmissions. Thanks for replying with your experiences.
Jeff

[mudman2]

I’m not a rocket scientist but I think your at the max towing ability for that rig. In other words everything is cool as long as it’s 72degrees sun shining and no wind. Just my thought. I have a 25 bds and tow with a 2015 Toyota Tundra and blue ox 10000 wdh. I know with a little wind I know I’m towing the rig.

[DieselDrax]

Originally Posted by mudman2

I’m not a rocket scientist but I think your at the max towing ability for that rig. In other words everything is cool as long as it’s 72degrees sun shining and no wind. Just my thought. I have a 25 bds and tow with a 2015 Toyota Tundra and blue ox 10000 wdh. I know with a little wind I know I’m towing the rig.

The trans temps climbing to the 220s and plateauing is normal operation for these truck with the 6L50 trans. It freaks a lot of people out until they know it's typical, the OP has nothing to worry about and it's not because the truck is maxed out.

[Reprise]

Terrain, altitude, and ambient temps will be your determing factors.

I just got back from 2700mi trip to Glacier NP, w/ a 5.3L Envoy rated for 7K (was towing 5k, per scale), with a (small) Derale cooler, WDH, built trans, & synth Dex VI. I have no T/H mode, so used 3rd.

Flat terrain below 80F - Below 160, all day (no higher than when not towing)

Flat terrain >90F: +20F max

Once past Missouri River / Cont. Divide - as high as 230 a few times; most of time I could keep / bring it down via careful throttle / RPM mgmt.

Once I got to 258F, and shut the truck down for 20-30min. Would come back on in the 220-230 range, and I could bring it down from there.

I'm going to beef up the cooler & explore some engine mods before next trip out west. May even swap a 6.0 for the 5.3; torque is my issue, as I had to drop speed for the steeper / longer climbs.

No burning of fluid / trans; shifts & runs as before the trip. Got to the point where I didn't even worry until I saw 220F midway through a climb.

On the way back, I crossed the Divide again at 6300ft w/ the fluid in the mid 160s /180s (forget which) More & cooler air on that climb, vs the outbound trip. I was as high as 8K (approx) during the trip. Decided against a side trip testing out the rig on I-70 / Greys Pass

[JPKflagstaff]

I have a Reese dual cam 800/10,000 WDH and have to say I like how its set up and its towing traits. So far on the highway with semi-rigs passing its been great, I was anticipating some push but it tracks very nice. I haven't seen major high winds, yet.
The setup is not maxed for my TV, close though. Technically I can tow 7K max and my 25LB (no slides) is 4530 uvw. My TV and TT weight about the same unloaded. After my mountain trip I'll let you know what the temps I see.
Thanks,
Jeff

[JPKflagstaff]

Mountain trip: When we left it was 83 f and 15-20 wind gusts and on the way home low 90s with the ac on.
It looks like I won't be trading in my truck, it did great.
Tranny temps were 180-198 and on the steepest grade it was comfortable at 40 mph and on all other parts of the trip I kept with the flow of traffic. Thanks for the help.
Jeff

[pilotpip]

Originally Posted by Reprise

Once I got to 258F, and shut the truck down for 20-30min. Would come back on in the 220-230 range, and I could bring it down from there.

I'm going to beef up the cooler & explore some engine mods before next trip out west. May even swap a 6.0 for the 5.3; torque is my issue, as I had to drop speed for the steeper / longer climbs.

No burning of fluid / trans; shifts & runs as before the trip. Got to the point where I didn't even worry until I saw 220F midway through a climb.

When you decide to pull off and let things cool down, keep the engine running. That will keep the fan on, which will move cool air over the heat exchangers (trans cooler and radiator) and also keep the transmission pumping the fluid through the system, cycling the hot fluid through the the cooler.

[Reprise]

Originally Posted by pilotpip

When you decide to pull off and let things cool down, keep the engine running. That will keep the fan on, which will move cool air over the heat exchangers (trans cooler and radiator) and also keep the transmission pumping the fluid through the system, cycling the hot fluid through the the cooler.

Thx for the suggestion - appreciate the reply.

As it turns out, I *did* leave the engine running for 10-15min at the beginning, in hopes that it would cool down. However, the trans temp (as reported by the OBD - e.g.; constantly updating) would not lower at all until I actually shut the engine off and waited.

The other item of note is that my external trans cooler on this vehicle is mounted in front of the condenser (per mfg recommendation). It gets the first shot of incoming external air as a result - but really, no air to speak of from the fan in the back. Finally, the cooler itself is a stacked plate - so, although mine is smaller, it is supposed to be the most efficient type (rated at 20K BTU/hr)

I also am taking into account the atmospheric changes with the elevation rise from < 700ft above sea level, where I live, to between 6K - 8K ft, which is where I ended up during the trip. Minor, perhaps - but it is a factor, IMO.

As it turns out, after discussing my situation with some people outside this forum who tow much heavier loads (most of them have diesels), I decided to upgrade my TV. Found a low-mileage Sierra 1500HD, which is basically a 2500 with a 'badge job' (GM created these, back in the day, to have the 'highest cap 1/2 ton' in the industry.) The only difference with the one I found was that it has a 3.73 instead of the optional 4.10 (the 2500 got 4.10s by default).

One benefit of the 3.73 is that I can get a little better mpg, at least unloaded - drove up to Milwaukee with it over the weekend, and noted about 17mpg, without much trouble/ effort (unloaded, to be fair.)

Am in the midst of getting it safely 'tow ready' - but once done, will be set for up to 9300 or so (and if I swap the axles from 3.73 to 4.10, I'll gain another 20%, capacity-wise). Still have the Envoy for now (and still using it to move the trailer, for now), but eventually, it'll be retired from towing duty.

Of course, now that I have a little more truck, I'm now planning for a little larger trailer - a bunkhouse where I can rip out the beds and use the space for an office. Just looking for the right floorplan (ironically, the FR Cherokee line seems to be a good fit.) I'm even looking at smaller 5th wheel bunkhouses, this time around.

It never ends, does it? LOL

[WolfWhistle]

On a trip out west with a 1500 Chevy 5.3L I noticed on several long pulls up a pass, my transmission temp would exceed 270 degrees which concerned me since on the flat I would see normally less than 200. I found that slowing down made a huge difference and usually with tow mode off I would manually "lock out" 5th / 6th; keeping it in a lower gear; as low as necessary including 2nd or 3rd. RPM wise, you have to let a gasser wind, even scream... that is where the power is and it won't hurt them. IMO, it is better to let it wind that put up with the up and down shifting, trying to keep the RPM lower, which seems to make the tranny hotter, at least it did on a 2010 5.3L 4x4. I was towing considerably lower than the max... max tow 9500# I was at 5000# at or very near the truck's GVWR but under GCVWR.

WW

[pilotpip]

A lot of people don't like to hear it, but as long as you're below red line, you're operating within the capacity of the engine. Let it take some of the load from the transmission. There's a lot more stuff there keeping it cool.

One thing about changing gears, while you've adjusted what the truck is capable of, the truck is still only technically capable of what's on the sticker/vin. Could be important from a liability standpoint. If it's 4x4, you're going to have the added expense of doing both axles.

The HD trucks, despite what your dealer said, are not "rebadged" 3/4 tons. They're 1/2 ton frames with a heavier axle, and heavier springs.

Likewise, your search for a new TT. All you're doing looking at small 5ths is putting you right back where you are right now. I'm of the belief that the 1/2 ton towable 5er is about as realistic as a decent sized TT that's SUV/crossover towable.