I have a 96psd f250 and I just bought a 23' camper.. I really don't know how heavy it is. The truck has 220K but it still seems to pull it fine unless going up step hills. My question is i'm I hurting my tranny by not shutting off the overdrive. I thought that shuting off the od was just to keep the tranny from shifting up down. If i'm going up stephills i shut it off. I don't see the reason to when i can drive 60 on flat or small hills with little effort. Is my thinking wright or should i leave the od off all the time when pulling and have the motor running at 2500rpm(@60-65mph)

 

Get guages, the biggest transmission cooler you can find, and drive by the temperature of the guage. In most cases with the extra cooling of the big cooler you can leave overdrive on all the time.
Also get a valve body kit to increase line pressure, that will reduce slip which creates heat.

 

General rule of thumb is to leave it in OD till the truck starts to hunt for gears.

 

kod and srm both have great advice.. to that i will ad this... get all your fluids changed to synthetic fluids.. syn fluids work better and stand up to heat better... and... use your tach and speedo to determine wether or not to use OD when towing.. i tow a 28' 5ver that weighs 10k lbs... my truck has taller gears in the diffs to lower rpms on the highway and give me better mpg... the downside is that i can't run OD in my mule while towning until i get out on the highway and get the speed up over 65 mph... not a problem though... i also put a very large cooler on in addition to the stock coolers i had... and... a tranny gauge and pyro gauge are a MUST HAVE when ever you are towing loads like this...!

 

I used to think that I would go ahead and tow pretty much all the time in OD. However, a recent conversation with someone whom I consider to be pretty close to an expert has altered my opinion just a little. A bigger cooler and a bigger tranny pan will help. This "expert" showed me a tranny cooler out of a 6.0L truck that he was adapting to run in the older trucks. It's a lot bigger than a Summit aftermarket cooler he showed me. Locking the tranny out of OD shoots more pressure to the bands inside the transmission, which reduces slippage, which reduces heat build up. With my truck and it's 4.10 gear, I have started leaving the OD off until I get up to about 60 on the highway. I like to keep the RPMs low normally, but just for a little while, I'll let them go on up toward 3000 to try and save that tranny, you know? Haven't done much towing in the mountains yet (but I will be soon), so I can only speculate that the OD should be off just about all the time there. Naturally, you want to be out of OD if the tranny is searching up and down, but that 60 MPH deal is part of what I look for now, too.........

 

Just like when you drive a stick, as soon as it bogs down in OD, then downshift. Just hit the button. No sense lugging your engine and straining everything. And visa versa if your rpms are too high. That's why that button is right there at your fingertips!