Yellow Yota

Well, first post.
Just bought a new to me 2500 Yukon XL. (Is it close enough to a Suburban to hang out here?) It's a 2005 with the 6.0 Liter.

My question is how well do the transmissions in these hold up with moderate towing? My boat weighs 5000 lbs with trailer, and my rock crawler is around 6000 lbs with the trailer.

I know I'm within the rig's capabilities, but just don't know how well the stock cooler works. Do those of you that tow regularly have an auxiliary transmission cooler?

It has a trans temp gauge, so I'll keep an eye on it. I was just wondering what others have done.

Thanks,
Chad

SabrToothSqrl

with a 2500 and that much weight your not even going to make that truck break a sweat...

DoubleO7

The transmission is factory designed to run at the same normal temp as the engine.

Running cooler or hotter is not the desired operating temp.

in2pro

I don't believe that is true, as my trans temp was at 117-129 degrees on the ride home from work yesterday while the engine temp was solid at just under 220...

EDIT: corrected temp reading of 220 to 210....

73shark

Yellow Yota: Welcome to the forum. It's fine to hang out here.

I agree w/ in2pro. Mine always runs cooler than the engine temp which is rock solid at 210*.

Yellow Yota

I do know that there is no such thing as too much cooling when it comes to ATF. Only thing would be during an extreme cold snap (which is not common in my area). At that point, you'd want to warm the rig up a bit before you drive.

I ask because I've always had a heavy duty tow rig. This is my first 'Burb, and I was just curious what temps folks see when pulling a load similar to mine. I'd love to keep my tranny temp under 200* to extend the life of the ATF.

I'm used to a Dodge diesel with a fully built ATS transmission, a larger cooler, and a double deep trans pan. It holds about 22 quarts. When towing in town, it would get nearly 170*, but when I get on the highway and the torque converter locks up, the temp falls quickly until the needle is sitting on the peg at 140*.

The family has gotten big enough to warrant a full size SUV. Going to the lake with 6 in the extended cab really brings the suck! We are absolutely loving the room and the ride of the new rig. Was just thinking about cooling......


Thanks for the input,
Chad.

73shark

Au contraire, there is such a thing as too low temp for tranny fluid. I know for a fact because on the '89 Chrysler minivans when they had an external tranny cooler, they did a recall to install a thermostat because in extreme cold climates (can you say International Falls, MN?), the fluid would actually slush and the tranny doesn't work well w/ a slurpy.

in2pro

Keeping the tranny temp under 200°F is preferred, and as 73shark stated it needs to be hot probably above 100°F sustained... and anywhere between there is a happy place....thou if you are running at 200 ° regularly I would suggest servicing the fluid at every 50k...
I think the owners manual says that if you live somewhere where it gets to 90 ° regularly you should have the fluid serviced at 50K or if you do any towing....

I live in Texas and it gets to 90° and I tow rarely but do tow, I have 51K and plan to get the tranny service at my next oil change....

DoubleO7

All automatics that I know of have a standard tranny cooler in the rad tank.
With that setup, the trans will be cooled and heated in conjunction to what the rad water temps are.

Kinda hard to think that they would have one design of tranny that likes it that hot and another design to run at 100 to 50 degrees cooler.

Now if you have a external tranny cooler, which is generally an option included in a tow package, etc. you should get some lower temp. If it is not mounted inline of the rad mounted cooler. Inline with a rad cooler would defeat the benefits of the external tranny cooler.
But the tranny is designed to operate at rad temps.
Operating somewhat cooler might be a benefit.
Or the thought of it being a benefit sells a lot of optional tranny coolers.

Yellow Yota

Pretty much what I said.. Cooler is better, but super cold is not.

I'll try with the stock cooler and see how the temps look. If I get over 200*, I'll upgrade.