Today I went down the mountain to buy hay. It was hot there- over 100F. I loaded up a stock trailer and started the drive back. (No, I didn't run the AC- just sucked it up and went!) Total weight- between 5-6,000. Not a lot that's for sure. The grade coming home runs between 12-17%. (that's not a typo) I had it in Tow/Haul and was taking it easy. About 40 minutes into the drive, and only about 10 minutes into the mountain climb it suddenly felt like I might be losing power, maybe the tranny slipping some. Up until then it was strong and staying at around 1800-2000rpms. It revved back in when I pushed it some and I continued. About 10 minutes more in the climb I could tell the tranny was having some issues as every time it shifted it shifted HARD with a big thunk. I don't have a temp gauge on it yet but wondered if it was getting hot so I pulled over, sat for about 5 minutes, then turned it off and let 'er rest for about 20 minutes in the cooler mountain air. Made it the rest of the way (20min) up the mountain with no issues- but I kept it in second. During all of this the other gauges were all within normal, no warning lights anywhere. The only thing out of the ordinary was when I turned it back on I got a light that said "check engine gauges"- which I'd already done but as stated everything was normal. I checked for codes before restarting it and got nothing.

So...does that sound like the tranny was getting hot? or something else? Did I do the right thing or was there something better I should've done? This sucks cuz I was really thinking my truck was just a good running machine! Please don't tell me to get a stick- not an option. Oh- this is not the first time I've pulled this grade with a load but it's the first time that I've pulled it in the heat. Help?

 

Wooaaa. Thought you were talking about the 68RE. Don't want to hear things like that happening to the new 6spd auto they bolted up to the 6.7L.

 

Wrong forum.But without a trans heat gauge who knows.Your truck has a built in trans overheat warning.Hope you wern't pulling this grade/load in high gear,overdrive.Hope you had it in tow/haul or overdrive off as the 06 has both features.

 

Ok- sorry! didn't see the 2007 and up just saw the 2003. I'll move it.

As stated in my post it WAS in T/H. No warning lights anywhere on dash.

 

Well, if pulling over and cooling it down helped then I'd say you did the right thing there.
Maybe it's time to get a tranny service and get the internals checked out...