Just got back from my first camping trip since buying the truck. I towed my 2200 pound tent trailer 80 miles away to the sand dunes for family fun. I noticed that as soon as I got up to speed on the highway, between 65 and 70, that the engine was making noticeable thrumming noise. it was revving pretty close to 3k rpm at this speed, and my transmission temps were about 170.

Since the road was relatively flat where I happened to be, I kicked into overdrive. Within 2 minutes, transmission temperature had dropped to 150. RPM at 70mph was 1936 according to my scanguage. I decided I'd leave it in OD until I started climbing any hills or the temps started to rise. Well Lots of rolling hills later, and the truck never downshifted to maintain 70, and the transmission temp never went above 155.

Is this normal? I thought for sure it would get hot being in OD with 5 people (3 of them kids) and a bed full of camping gear. It was only 70 degrees outside so not like its summer hot yet.

I have 3.73 rear end with HUGE factory transmission cooler (Biggest stock coooler I've ever seen, waaaay bigger than my father in laws Duramax 3500). Am I good as long as the temps stay low, or am I doing other unseen damage towing this kind of weight in OD?

When I got into town off the freeway, I locked out OD for any speed below 50 just to make sure it would not lug, but seemed to have plenty of highway power in OD and no problem keeping 70-75mph speed. AND to top it all off, I averaged 16.2mpg (hand calculated) for the tank of gas which included a week of in-town driving and the 160 mile tow.

Is anyone else having similar results? The true test will be when I throw my 700 pound wheeler in the back and tow the trailer up into the mountains in a few months. Transmission fluid is nice and red too, no funny smells.

This is the rig I towed:

I just recently did spark plugs, COPS, fuel filter, air filter, Brakes, rotors, VCT solenoids and added load levelling rear shocks. Besides a little timing chain noise at cold startup and slight diesel sound when warm, runs like a champ. Not fast by any shake of the stick, but getting the job done.

 

the temps dropped because the torque converter was locked in 4th when you turned OD back on. unlocked it produces more heat.

 

Sounds like your truck is doing a great job! As far a temps you were well in the safe range. And like the previous person said, it cooled down when the torque converter locked.

 

So unless it starts hunting for gears between 3 and 4, or unless the temps start to climb high I should be OK to pull this trailer in OD?

 

Does anyone know what the safe operating temps are? I've hauled a pretty big trailer before and it was at 185F but I've had it reach 200F before

 

X2 I've had it hit 200 before but maybe once. Since I'm in Texas in dead of summer I can seeing it get to that temp.

 

IMO you'll be fine. Like you said if it starts hunting for gear or climbing temps you'll be fine. I pulled my wife's yaris and a bed full of stuff for a move from Utah to San Diego ca. Through mountains and the desert. Most the time I was on over drive and cruised at 75 to 85 and the temps never went over 185. When I hit really steep hills I shut OD off and stuff to 55 till the crest. Be smart about how you pull it and you'll be fine.

 

Ok cool ill just smarten up when I'm towing

 

Haha ya I had to do the same thing. I learned from my cousins mistake. He smashed his tranni. Of course he had a trailer did a four wheel drive launch on full boost in a lifts cummins but that was enough for me. When I can afford to fix it that's when I'll get stupid with mine.

 

Ya I definitely don't wanna do that lol