jeepsuck

at what point do i need to hit the od killswitch? im going camping this weekend and i will be heading up the cajon pass which is quite a long, relatively steep grade. the truck will be loaded decently, but nothing outrageos. a crapload of firewood, few gallons of water and the usual camping stuff + firearms and ammunition. maybe 1000lbs?

boomer

No OD below 45 mph, is what I was told. The OD clutch pack is the weak link in the trans.

Brock

Do you have the TOW/HAUL button capability as well on your selector? I was told when towing or hauling heavy loads to use my TOW/HAUL selection as it changes the shift points out further.... If in heavy traffic with starts and stops or if driving in mountains or somewhere that speed is causing it to shift in and out of OD...then use the OD OFF selection.

Sorry but not familiar with what you may have in your truck....but I have both in the 06.

boomer

No tow/haul selection here. Only OD on/off. I have my OD on a toggle switch for on/off so when it's off, It stays off and when it's on, It stays on (no shifting via the computer/TPS). I towed heavy loads for 11 years and averaged 450,000 miles per trans with setup.

Tuckerdee

You'll never fall below the speed limit on Cajon pass with only 1000 lbs. I towed my 5th wheel to to Southern California last year. On the way over the pass headed east I never fell below 65. The fiver is around 6000 lbs.

wannadiesel

Are you running any gauges? As long as EGT and trans temp are OK you can leave it in OD. If either one goes up, drop it out of OD.

Tuckerdee

My experience here in the mountains of Colorado is that the coolant temp and the trans. temp sorta/kinda/almost/usually run hand-in-hand. Since there's the oil/water heat exchanger, which seems to work fairly efficiently, the two fluids seems to match temp pretty often under towing conditions...at least this is what I've found on my truck. When the coolant starts heat up, so does the transmission fluid. Or is it the other way around? Let us know what you see after your weekend.

wannadiesel

I think on a 1st gen it's the torque converter driving up the engine temp.

jeepsuck

i hope so, i imagine my foot will be in the floor most of the time. going up the 73 toll road i think im maintining about 65-70 with my foot at WOT, boost at 20, EGT at about 7.5. so far my egt's have been keeping me very happy. i've never seen 900*. maybe that banks intercooler is actually doing a pretty good job. then again, i've never towed or hauled any heavy loads over a grade, and i dont think anyone has played with the pump at all. i have never seen the tranny temp rise above 160*. i have no idea where the probe/sending unit is and really not the slightest clue where to look .

thanks for the input.

Karsten.

Boatnik

According to the owner's manual, the OD will drop out automatically when the ATF hits 278 degrees F. It reccomends to take it out of overdrive to prevent excessive shifting like what you see when running up and down short hills. I'm towing a 27 foot Bayliner Trophy with a Tee top during the summer running A/C with the air temp pushing 100. The boat and trailer combination weights about 7200 pounds and I am not afraid to run above sixty. I never have felt or noticed it to drop out. The big concern was EGT. 1300 preturbo comes quick. Granted I am at sea level and there are no "hills" to climb but if everything works like it is supposed too you shouldn't have any trouble. Just watch your temperatures and don't get in too big a hurry.

The transmission fluid temperator sensor that controls the OD is in the transmission cooling line going to or from, i'm not sure which , the cooler on the drivers side near the transmission. The temp. probe to the gauge could be in the line too or in the oil pan.