20k miles on a 2011 3500 pulling a 12k 5th, I have added an aftermarket deep tranny pan. We have been on the road for 3 months and the truck is working very well. Started in Vermont and pulled across the upper US through South Dakota and then onto Oregon (some pretty long and steep pulls during summer temps). No issues, again the truck have been flawless. We are now in Calif. and were on a long connector road (50 miles) with tight curves and steep grades (maybe 7% or greater). Outside air temp was ~75F. It was a slow pull in 2nd gear (>2000 RPM) and I was seeing via EVIC sustained tranny temps > 225F (max 237F). Funny thing is, the radiator fan never kicked in because I never saw an increase in water temp. Is this too hot for the tranny?

 

I am interested in what the replies are. I run an Edge Juice only to monitor the engine and trans and use it for the turbo cool down timer. I have never seen temps over 160 and I have the stock pan. The temp I am getting is from the Edge, not from a dedicated gauge in the pan or the lines. Normal empty temps are 125 to 134F and whenever I hauled heavy...12K range I never saw the temp over 170F. I do not know where the Edge is taking the temp from other then the ECM.

 

Mine usually peek at 185 and maybe 190 when pulling over the coast range. I have never seen it above 200. It usually uns around 160 and stays there, might be different in your tranny. The 48re is garbage.

 

My 2011 has hit 220 a few times during the summer when towing up long hills. There are some post on it. Seems fairly normal that the 4th gen with the 68RFE runs hotter.

 

Hey there! We just hauled our 12,000lb 5'r over the Rockies through the Rodgers Pass. There were some pretty long stiff climbs that required third gear and a couple of 2nd gear stints at close to 3,000RPM. Trans temps, according to the Edge monitor with sensor in the trans pan, did not break 170deg. From what I have read here on the forums anything over 200deg is starting to cook the trans fluid. To the OP, have you pulled the dip and looked at the color of your trans fluid? Methinks that at 237deg it will be a fairly dark color and maybe even smell a little burnt? If so it would be smart to perhaps have the trans fluid changed out for some fresh stuff - might save you some $$$$ and frustrating warranty issues in the long haul. Just my .02 - YMMV

Cheers!

Mike

 

I believe the 68RFE comes with full synthetic fluid which can handle higher temps. My fluid still looks and smells new after reaching 220 on several occasions. Others have posted the same. As far as I am concerned it is under warranty and if it fails they can fix it. That is the only reason I have left my truck stock.

 

Not a big deal. Fluid break down is a function of temperature and time. 240* for 20 minutes is not as important as 240* for 20 hours.

The other facter is where you have the trans temp probe. The stock temp probe is in the pan. Aftermarket moniters that plug into the OBD port display whatever the ECU reads. Pan temps are not the hottest temps in the trans, and are probably the coolest. Apparently, the hottest temps are at the outlet port, as the fluid heads to the cooler, and then back to the pan.

If you're reading pan temps at 225*+, your hottest temps are probably considerably higher than that. But, again, your temps are not up that high for very long.

As said above, the big advantage to synthetic oils and fluids is their ability to resist heat. New synthetics can handle a lot of heat.

I wouldn't worry about it too much, except to plan on stopping at the top of the hill for a while and let things cool off - with the engine running and the hood open. I would also follow the heavy duty service schedule.

Going up the hill to Yosemite?

 

Thanks for all the replies. I did pull the dip stick this morning and while the fluid was darker (not brown) it didn't have any burnt odor to it.

I did pull over and let it cool off some maybe 10 degrees, but within a short while it was back up.

And yes, we are now in Yosemite. The road that started it all was Hwy 49, between Oakhurst and Moccasin. We wanted to stay at the north west entrance to access the Tuolumne area and were coming from the south. Regardless of the tray temps, the truck worked very well. Some sections I was in 1st with the e-brake on going down and around some steep curves.

I'm my own maintenance tech and I did put in the expensive stuff when changing out the pan and will most likely change it soon as I will have the time and a place to do it.

On another note; oil changes are interesting, when not pulling I will get the message every 3500 miles, if pulling, light won't go on until 7000 miles. The truck likes to work.

 

I always put tranny. in neutral to let cool off. If you can keep the TC locked it will run much much much cooler just keep an eye on EGTs. That is were the mystery switch works well for the tranny..

 

Don't let it switch gears too much in the hilly areas even if you have to let it run at a higher rpm is what I do and the trans temp on my particular truck doesn't go up much even towing heavy.


Let it switch gears a lot and the tranny heats up. Let the motor bog and the EGT's go up too.

 

Very good info here:

http://www.digi-panel.com/trannyoil.htm