2200 mile trip and now sold!

[Runaway]

Just got back for the Black Hills of SD/Wy. Spent some time up around the Devils Tower area. This was the first real tow for my Dmax and haven't really jumped on the Dmax bandwagon even though I've had it for 6-months now. But got to say all of the reports of gassers out pulling it etc, etc, etc haven't learned to drive a diesel. I can now report I AM A SOLD DMAX CUSTOMER! My 5ver isn't as heavy as some of yours are but I do carry a lot of frontal area. I traveled between 65 - 68 mph while on the big highway(Never did see any of you guys who pull theirs 75 & 80). My best mileage was 12.68 and my worst for the trip was 10.03. Overall I average 11.26 for the trip. I was never passed by another RV combo and I think I only passed 2 or 3. I started the trip a half quart low on oil and thats where it still is. The Allison is one sweeeeeet auto tranny for towing. Its a good thing I read about the posts on its grade braking in the steep grades. Is it normal when the temps outside are in the 80s for the tranny to see 170* temps? I felt the tranny may be running too hot! Only problem I had was the driver's side rear axle seal let loose (now both sides have been replace within two months) and I hope I have no more axle seal problems. As I told the better half on this trip, this is one sweet towing machine. :D

[Modified]

170 Deg F is not too hot. Pulling 9000 lbs at 90 Deg outside, I usually see 190 to 200 Deg F on my tranny gauge. Not sure how accurate our tranny gauge is.
I've read the optimum tranny fluid temperature is 160 to 200 Deg F. If you're not pulling loads continuously, your average temps will be much lower. These are some fluid life ratings I've seen based on fluid temp:
160 Deg F may get you 100K miles of life
180 Deg F may get you 50K miles of life
200 Deg F may get you 25K miles of life.
As you see, 20 Deg more temp reduces your fluid life by half. I believe these ratings are for conventional fluids, and the synthetics are usually rated longer life, at higher temps.
As to what is too hot, if I believe our trucks will initiate a SES when tranny temp reaches 250 Deg F.

[DieselDixon]

Well this bothers me a little bit. I get 150 Deg F just driving around town with no trailer. What are you guys getting when unloaded? I will find out what it is towing in a couple of weeks here, I have a 8k lbs trailer that will be hooked up.

Hey runaway, I was wondering what you have read about this "grade braking" on steep grades? The biggest grade I will have to make in both directions is a 7% for 3 miles.

[Captain Mal]

Transmission temps. are always in the 150 to 200 degree range for me. Normal unloaded temps. vary from 140 to 170 or so. Just towed in 112 degree temps. last week. The transmission did get up to a slight bit above 200.

Love the Allison, not so with the Duramax but that's another story.

[Runaway]

Modified: Seen those guidelines on aftermarket tranny coolers for oil temps. Where in NE Wisconsin are you. I'm near Green Bay.

Diesel Dixon: John Kennedy's web site has an excellent write-up on the grade braking feature the tranny has. Others have reported what I experienced when coming off a steep grade to where when the tranny downshifts you may be in the dotted red area in RPMs according to the tach, which is normal when grade-braking

[hoot]

It won't hurt to suppliment the tranny grade braking with a little real braking.

[PJD15X]

No need to worry about your transmission temperature running near the 190-200 mark. It is piped into the radiator, therefore the temperatures will run close to what your water temperature is unless you have added an external trans. cooler. Just monitor both gauges occaissionaly. It is normal for it to go up on a long uphill pull, but should come down to operating range when going down the other side.

[Norm B]

I live in the mountains with about 3000 foot elevation climb with slow corners for 20 miles to get home. I will see a 10-15 degree lower tranny temp when not towing by running in tow/haul up the hill. Helps to lock it up! When towing I always switch to tow/haul on any extended grade even though my trailer is not that heavy(26 ft). The temp very seldom exceeds 200. I take it out of tow/haul on level towing or around town because the shifting gets a little harsh at lower speeds. I have 22K miles on the truck now with probably 60% towing. Not a single problem . Love it!!!!!

[Kennedy]

Not to sound condescending guys, but this is one of the reasons mfr's have been reluctant to put in gauges for things like this. I have found that my ATF temp will vary in sync pretty close with ambient temps. It will run in the general range of around:


90

[DieselDixon]

Runaway, I'm in Northern Ca.

That was an interesting article that John had, I did not know that it was active in both normal and tow/haul mode.

It looks like my tranny temps are in line, like I said I will find out for sure in a couple of weeks.

Thanks

[TEXASTOUGHDMAX]

JK....Thanks for your temp examples. I had just posted a concern about this (200deg w/95deg ambient) in another thread before I read this one. My only concern now is that I haven't switched to the Synthetic ATF. I guess I need to do that ASAP. Also I still have the OEM pan.

[Modified]

Runaway :

Yes, I live near Green Bay. Another season is just around the corner.
If you want to know more, and don't mind posting your E-mail address, we can talk more.