2011 Silverado 2500 trans cooler

intheburbs wrote:

SidecarFlip wrote:

Ralph Cramden wrote:
I have had the 6.0 in 3 different 2500's, 2007, 2013, and 2015. I tow a 5+ mile long grade often, at least a dozen times a season, on the way to a PA state park that exceeds 9% for the most part pulling 6000 lbs or better. I have only seen transmission temps above 200 pulling that grade a few times, around 205, and that was when ambient was in the low 90's.

Usually temps are between 165 and 185 pulling that grade. I also am not babying the truck when doing so, 50 to 65 mph wound out @ or above 4500 rpm.

Playing race car driver huh?

Blowing that carbon out of the exhaust system.........:E

Are you even aware of the specs on this engine?

SAE horsepower, hp @ rpm 352 @ 5400
SAE torque, lb-ft @ rpm 383 @ 4300

So that means the optimal power band is between 4300 and 5400. So what's the problem?

In all actuality, my comment was to 'Ralph' and not you at all.

having said that, 'Ralph' and I are friends off forum and I was merely poking some fun at a friend.

IOW your comment was not warranted or appreciated.

I'll let it go at that and I would appreciate it if you did the same

SidecarFlip wrote:

Ralph Cramden wrote:
I have had the 6.0 in 3 different 2500's, 2007, 2013, and 2015. I tow a 5+ mile long grade often, at least a dozen times a season, on the way to a PA state park that exceeds 9% for the most part pulling 6000 lbs or better. I have only seen transmission temps above 200 pulling that grade a few times, around 205, and that was when ambient was in the low 90's.

Usually temps are between 165 and 185 pulling that grade. I also am not babying the truck when doing so, 50 to 65 mph wound out @ or above 4500 rpm.

Playing race car driver huh?

Blowing that carbon out of the exhaust system.........:E

Are you even aware of the specs on this engine?

SAE horsepower, hp @ rpm 352 @ 5400
SAE torque, lb-ft @ rpm 383 @ 4300

So that means the optimal power band is between 4300 and 5400. So what's the problem?

Ralph Cramden wrote:
I have had the 6.0 in 3 different 2500's, 2007, 2013, and 2015. I tow a 5+ mile long grade often, at least a dozen times a season, on the way to a PA state park that exceeds 9% for the most part pulling 6000 lbs or better. I have only seen transmission temps above 200 pulling that grade a few times, around 205, and that was when ambient was in the low 90's.

Usually temps are between 165 and 185 pulling that grade. I also am not babying the truck when doing so, 50 to 65 mph wound out @ or above 4500 rpm.

Playing race car driver huh?

Blowing that carbon out of the exhaust system.........:E

I have had the 6.0 in 3 different 2500's, 2007, 2013, and 2015. I tow a 5+ mile long grade often, at least a dozen times a season, on the way to a PA state park that exceeds 9% for the most part pulling 6000 lbs or better. I have only seen transmission temps above 200 pulling that grade a few times, around 205, and that was when ambient was in the low 90's.

Usually temps are between 165 and 185 pulling that grade. I also am not babying the truck when doing so, 50 to 65 mph wound out @ or above 4500 rpm.

^^^^^ Great post ^^^^^

A good friend of mine is a transmission validation engineer at GM. When he was first hired, his first platform/project was the validation of the 6L80/6L90. I queried him about transmission temps because I was towing out in the Rockies, and I was seeing temps as high as 235°.

He assured me that they did much worse to these trucks in validation than I could ever do, and that the stock cooler is more than adequate for the job. The "transmission hot, idle engine" message only comes on at 265°. Dex 6 is really that good. I have no plans to upgrade the transmission cooler.

Having upgraded trailers (again), we saw even higher temps in our trip out west a few months ago. I was not concerned at all. The truck has 170,000 miles on it, still runs/shifts perfectly, and I beat the snot out of it. This pic is while we were ascending towards Powder River Pass, elevation 9666':

Thanks for the info.

Hawkeye-08 has the same rig as me and I'll max out at8k on the trailer. Guess I'll be watching the temps at first. Should be able to do a trip at the end of the month to see how we do. Outside temps would be about 60 around here so no worries there, it's just the 90s where I'll be curious to see how it does.

With the new 6 speed transmissions and dextron VI fluid, you can go much higher on temps than in the past.. If I recall, factory says you can go up to 265F, but personally, I don't like it that high. On a hot day pulling up a big hill, my temp will get up to 215F, but cools down pretty quick as soon as I crest the hill. I plan on replacing (or adding to) the factory cooler in front of radiator.

I have the 2011 GMC 2500HD 6.0/6sp/3.73 CCSB 4WD pulling Arctic Fox 27T (~10k lbs this trip). We just came back from camping over Labor day weekend, temps in low 90s, pulled long hill, got up to 210F. We ran into strong headwind on trip home, mileage was down around 6mpg, which gave us 7.2mpg for round trip.. The campground we went to is just over a 100 miles away, but getting there has lots of ups and downs. I use tow/haul but leave the cruise off.

Our previous tow vehicle was 2008 GMC Yukon XL Denali with a smaller trailer. The trans temp went to 235F on big hills on that, definitely was adding an additional cooler if we had kept it.

I've had my 2010 2500HD for 7 years and have towed in some really hot weather, long distances and up grades. Never had a transmission cooling issue w/ the Allison. I do make sure I change the fluid every 50K miles. I find that it gets the highest in stop and go traffic when its hot out, not rolling down the road. But it's still well w/in limits.

ScottG wrote:
I would install a trans temp guage (if it doesn't already have one) and do nothing unless it gets too hot.
You can over-cool trans fluid - you want it to get over 140 degrees on a regulaar basis to burn off moisture.

Most top tier trans coolers like Hayden are internally thermostatically controlled for flow. At least mine is.