My 2015 2500 HD has the Allison 1000 (6-speed) trans in it. I was kind of disappointed to see the truck did not have a trans temp gauge on the dash, which my 2002 gas HD truck had. And I was also surprised that you can't even check the trans temp through the Driver Info Center (DIC) menu on the dash. Even my son's basic 2008 half-ton with a 4.8 gas engine has that feature. I know these HD's with the Duramax/Allison engines have a massive trans cooler up front, and a large opening in the bumper to flow a lot of air to the cooler. So is that why there is no factory means of monitoring trans temp?
Maybe it is simply not an issue at all. I have checked the fluid level a couple times, it usually looks a bit low, but then I can never seem to get it to what I would consider to be "hot", (approx. 175*), so I don't want to add any fluid, knowing it will raise the level on the stick if it does ever get hot.
a couple of days ago, the weather was near 80*, I drove 35 miles after I left work, which included 30 miles of highway, then 5 miles of stop and go traffic, then I stopped for fuel. Before I shut the truck off, I checked the trans fluid, thinking it should have been very hot at that point. It was basically at ambient temperature. I actually wiped the fluid off the stick with my finger and thumb. That seemed really strange to me, especially since the trans sits behind (and is bolted to) an engine that runs at around 190/200* coolant temp.
So maybe that big cooler is overkill, and they decided no need to monitor fluid temp? Anybody add an aftermarket trans fluid temp gauge to their truck? What trans temperatures do you see on yours? Not being able to see that reading, especially on long highway runs, towing heavy, when 100* summer temps roll around, is really going to bug me.

I've seen 220-230 on mine towing in the mountains with zero issues. The trucks I work on are regularly in excess of 250* without issue, even hotter on the ones with retarders. Transynd is good stuff, takes a lot to hurt it. I wouldn't worry about it, you'll melt your engine down before you hurt the fluid

My 16 GMC 3500 NEVER gets above 160, and that is only when it is 90 outside. We went to St Louis this past weekend, with highs in the low 70s, and it was running at 120 degrees, and that was towing a 32' trailer with a dragster, golf cart, scooter, decent sized tool box, 50 gallons of fuel and misc stuff.

Let's see if I can get you to your trans temp in your DIC.

Go to select options in your DIC then select info pages. Scroll down till you see transmission fluid then check the box.

To get an accurate reading on the fluid level the temp should be at least 160 degrees.

Also, if that trans overheats the DIC will display a warning message until the temp falls below 265 degrees.

quote:

Originally posted by 329L:
My 16 GMC 3500 NEVER gets above 160, and that is only when it is 90 outside. We went to St Louis this past weekend, with highs in the low 70s, and it was running at 120 degrees, and that was towing a 32' trailer with a dragster, golf cart, scooter, decent sized tool box, 50 gallons of fuel and misc stuff.

Sorry to tell you this, but your gauge isn't working.

The computer thinks its running at that temperature, at least that is what the Snap on scanner from our transmission shop said.....

quote:

Originally posted by 329L:
The computer thinks its running at that temperature, at least that is what the Snap on scanner from our transmission shop said.....

If you work at a transmission shop and think that your oil never exceeded 120° loaded/towing, then you might want some CEs.

quote:

Originally posted by Trans Lady:
Go to select options in your DIC then select info pages. Scroll down till you see transmission fluid then check the box.

Trans Lady, thank you, I had to work my way through several "menu's" to find the check box, but it was there.
I appreciate the help, and will report back on the trans fluid temp reading, after I get a run that should put some heat in it.

quote:

Originally posted by Roger McGinnis:

quote:

Originally posted by 329L:
My 16 GMC 3500 NEVER gets above 160, and that is only when it is 90 outside. We went to St Louis this past weekend, with highs in the low 70s, and it was running at 120 degrees, and that was towing a 32' trailer with a dragster, golf cart, scooter, decent sized tool box, 50 gallons of fuel and misc stuff.

Sorry to tell you this, but your gauge isn't working.

1. I have never seen it over 165. FACT
2. This weekend towing 195 miles from Evansville to Indianapolis, which is relatively flat ground, it would run 120-130 on the highway from 60-75 mph. In the city, under stop and go conditions it got up to 165, but once got going on the highway again it dropped back to 120-130.
3. I have double checked pan temps with sensors, and my gauge is accurate.

Moral of the story is, who the hell knows what the difference is between you guys down there and guys up here, but for the most part, the NEWER Allisons, 2012 and up, run much cooler than the old ones, AND they run a bunch cooler than Ford or Dodge. The Allison transmission in 2500/3500 trucks is the LEAST replaced transmission out of ALL manufactors with those style of trucks. For a transmission to live like that, it has to run cooler. As you should know, heat takes the most life out of any transmission.....

The ONLY Allisons I see with trans temps North of 200 degrees, are when they have already burned up.

Haven't yet checked the temp while towing, but yesterday afternoon, it was over 80* here. 38 miles of interstate at 70-75 mph, trans temp never got over 130* (Guessing because converter stayed locked up entire distance).
After that, 14 miles of urban traffic, lots of stop & go, never got to 45 mph where the lockup kicks in. Trans temp went up to a max of 151*, until I got back on the highway, where it quickly dropped to 140.
Still amazed that it doesn't run close to the coolant temp of the engine bolted to it. Makes me want to put one of those coolers in my race car...

quote:

Originally posted by FootbrakeJim:
Haven't yet checked the temp while towing, but yesterday afternoon, it was over 80* here. 38 miles of interstate at 70-75 mph, trans temp never got over 130* (Guessing because converter stayed locked up entire distance).
After that, 14 miles of urban traffic, lots of stop & go, never got to 45 mph where the lockup kicks in. Trans temp went up to a max of 151*, until I got back on the highway, where it quickly dropped to 140.
Still amazed that it doesn't run close to the coolant temp of the engine bolted to it. Makes me want to put one of those coolers in my race car...

^^^This is what we normally see when one is running correctly

I gotta say, the exposed trans cooler on these Duramax trucks bothers me. May not be a real problem, but it just looks like it could turn into one in the wrong situation. I don't drive a lot of gravel roads, but if I did, and had to follow someone, I would be really worried about rock damage to the cooler. (Heck, some of the bugs here in TX can probably mess them up pretty badly!)
I bought a billet aftermarket grill to put over the cooler opening, it was very low cost, ($25 and free shipping on Amazon). I chose the black powder-coated version, since my truck already has too much chrome up front. Came with 2 brackets and all needed hardware, and some sketchy instructions (that tell you to remove a bunch of stuff to access the mounting holes, which was completely unnecessary). Took me 25 minutes to install, all from the front, using only a stubby Phillips screwdriver (oh, and a rat tail file to slightly elongate the mounting holes on the brackets). I think it really improves the looks, in addition to helping protect the tranny cooler from rocks, bugs, or the over-zealous car wash guy with a long-handled brush.
Here are before and after pictures, (if I can remember how to do this):
Factory Exposed Trans Cooler
Billet Lower Grille Installed
I put it on Wednesday night, and was curious how it might affect the trans temp, but apparently not much, if at all.
Yesterday was very close to 100* here, (my dash said 95 on my way home), and when I exited the highway after 45 miles, trans fluid temp was 151*. Then several miles of sitting in stop & go traffic, (mostly stopped, with truck in gear), it crept up to 165* and after finally getting it moving again, a cop had a guy pulled over on a scooter and blocked 1 of the 2 lanes, so again bunched up and hardly moving, no breeze at all, and the temp briefly moved up to 171*, (hottest I have seen it so far, but also hottest day of the year to this point). As soon as I got past that mess, and on to fairly open boulevard with a few traffic light stops, trans temp cooled back down to 154*.
If you think flying objects might be a risk to your trans cooler, I recommend looking into one of these, (or something similar).