I just got back from my big summer vaca, hauling my 45ft/ 21K toy hauler from NY down to Texas, New Mexico then up to Arizona and then again up to Utah for a nice week in one spot. Just got back to central NY last night. No issues or complaints at all EXCEPT....

I got at least 6 overheating [red warning messages] while treking up some of the steep mountains, some were 6%+ grade. A couple of times I got put in "limp mode" where it would only let me creep up the hill at about 15-20mph. The temp reading was in access of 245* (when I got the red box and the temp meter went into red as well).

Kind of embarrassing on a $80K new truck with only a few thousand miles on it (I think now it's about 8K on the meter, once back). I never once had an issue like this with my other diesels, then again in PS's defense, I never pulled a load this big either!. Shouldn't happen as I'm still under max pull at 21K.

Hope there's a fix?!?!?!?!

PS; And I gotta admit, I was really red faced while in limp mode when my fellow GM buddies went by me laughing their ***** off. Man.......... that sucked!

 

That is terrible, Top_Speed1. Probably going to be a very hard issue to "fix" since the dealer likely won't be able to recreate it.

If I recall, your dually has the 3.55 axle like mine. Max tow limit is 27,300lbs (maybe slightly less on a 5th wheel setup). That's more than your buddy's GM trucks are rated to pull. So they can stop laughing. But clearly, something is not right since your truck is capable of pulling quite a bit more than it was when it overheated.

 

Easy solution: Get rid of all your GM driving buddies.

I hope you find a solution. This is the first over-heat I've head about for a 2017.

 

What was over heating?

Engine Oil, Coolant, Tranny?

At 248° I suspect you are referring to the Engine Oil. I wonder if there is an larger after market Oil cooler?

It's been a very hot summer. But I have not seen any over heating with my 2015 SRW truck and I've pulled some 16,000 lbs loads up a bunch of 7% and 8% grades.

Good luck on your research

 

Maybe there's a fan clutch issue.

 

It was the coolant temp gauge (2nd to left/ upper smaller gauge cluster). Once you get the coolant temp up to about 220* you get the digital display reading above the gauge (like what you can trigger-on within FORscan), but the number digitally comes up when hot as OEM. This number reads white until you get around 250*, then this temp gauge switches to red, also a big message box pops up [in red] telling you the engine coolant temp is too high.

The first time this happened, I immediately shut down the A/C. This helped somewhat dropping the temps back down to the 240's. It also kept me out of limp mode. On a following big mountain, I prior turned off A/C. It kept me out of limp mode but I still went red on the temp gauge.

I guess I need to find some owners who haul heavy (real heavy) and at steep grades plus also in higher outside heat ranges. To add to this, we hit 90's much of the trip, a few 100's and in Albuquerque NM we had 115*F that day.... funny thing is, I never got a single overheating warning on the New Mexico leg of the trip. Hmmmmmmmm

 

That's funny on the GM guys because a certain generation Duramax (I don't remember which one) had a history of cooling problems, especially towing heavy. I purposely tried to overheat my 2012 6.7 while towing 12,000-13,000 lbs ( I know it's a much smaller load) through flagstaff and once that temp gauge would start to climb the fan would kick on and keep the temps down. I wasn't abusing the truck, I just wanted to make sure that the cooling system was working.

 

I've been hauling the same weight with mine and never has the coolant gone over 220 irregardless of grade or outside temp. Very strange. Coolant level low?

 

I will add some mileage stuff here, my loop was just a shad shy of 6,000 miles. I experimented quite a bit, taking note on head/tail winds and speed variations.

On purpose I did the following for each days trips...
Central NY -> S. Ohio (no wind, no mtns) cruise locked in @65mph = 9.1mpg (Fuel stops only)
S. Ohio -> Oklahoma (slight cross and head winds, no mtns) @70mph = 8.7mpg (Fuel and toll stops)
Oklahoma -> N. Mexico (no wind, mod mtns) @75mph = 8.5mpg (Fuel stops only)
N. Mexico to Arizona (slight cross winds, mtns) @70mph = 8.6mpg (Fuel stops + Site Seeing stops)
... then the Utah Mtns.... 65mph cruise locked in, 8.5mpg. We explored in Utah for a week hitting up the "Big 5 National Parks". Our daily touring was by motorcycle however.

Got home, the overall trip meter says 8.7mpg. Is this bragging material? No, but I'm not complaining either. Could be worse hauling this around, and I must admit it doesn't lag on the hills either!... other than my "Limp mode" (real) Mtn climbing experiences.

 

Coolant level is slightly above the full mark, as per factory fill.

I had no issues like this in the Smokey Mtns. back in May. But the Rockies are not comparable either, and I only had my issues in Utah. Two variables vs the Smokies...

1. Much much bigger elevations, even before you climb a Mtn you are at 7-8K feet. Summits are 12K and up. So the air is thinner up there, not sure if that had anything to do with it or not.
2. Steep % grades. Nothing like this on the East coast to compare.

Could be a combination of both of course. I really don't know. I can tell you that I won't be able to replicate this for the dealer. No way, at least not on this side of the Mississippi.

On the engine fan clutch kicking in... It did on the big climbs, you can hear the whine/whirl of it. I cannot say I heard this (ever) before this trip.

 

Any transmission temperature issues?

On my first tow with my trailer I was watching engine oil and transmission temperatures (243 and 232, respectively). I didn't notice the engine coolant temperature. I wish I had kept track of that. Do any of the monitoring apps (like Torque or Torque Pro) provide logging so you can review?

 

I don't know enough of bout the 6.7L cooling system (yet) but air in the system maybe?

 

Nope, no other warnings or messages. The truck pull was awesome other than the coolant overheating in Utah.

I gotta admit one thing, I made the right decision to go with the dually. It may not be sexy but it is one sweet pulling machine. Wow wow wow is all I can say, what a nice no stress, no sway pulling machine. Love it!.... just would not like to go into limp mode and have my following Chevy/GM friends laughing at me! In my shameless defense, they only have 34ft-ish; much smaller campers. And, I heard plenty of the FORD POS jokes around the campfire conversations. It's something I have to rub off since I was a past GM TV guy and I migrated away to the new Ford.

Oh well, hope there's a fix is all, software or hardware. I love the truck and the pull, I'm not switching back to GM... don't worry fellers!.. I'm here to stay!

 

From my powersprt background, this has been a big issue and a resolution found as an air-lock. But..... Since I did the Smokies with not even the digital readout coming up on the temp gauge... I'd say this is out of the question (at least in my circumstance here).

Thanks tho, keep the solutions coming, sooner or later I hope to find the answer!

 

Question. Were you using the "D" mode on the transmission selector and letting the transmission downshift and the engine to run at higher RPM, oir were you using the "M" mode, holding the highest gear possible and keeping the engine RPM down??