unable to turn off OD, tranny overheating?

[yob_yeknom]

I usually drive around town and on back roads with OD turned off to try and keep the tranny from shifting itself to death since I got my 31's. I don't do much of it at a time before I hit open roads and turn OD back on.
A couple of nigths ago I did a lot of back road driving, probably 1.5 hours, with OD off. I pulled into a gas station to get a drink and turned the engine off. When I got back in a cranked the engine, I pushed the OD button to turn it off and the OD OFF light did not come on. I pushed it again, thinking maybe I didn't push it hard enough the first time. Still no light. I figured maybe the switch was going bad so I pushed it a few more times with no luck. I figured the switch was shot so I gave up and started driving. About 3 or 4 minutes down the road, the light suddenly came on and it kicked out of OD. This only happened that one time and I haven't had any trouble out of the tranny.

Any ideas? Could I have gotten the tranny a little hot with all of that back road driving? Could the computer have had OD stay on to lower the shift points to help the tranny cool down, and then when it had cooled let OD turn back off? Possibly just a loose connection on the OD OFF light? (my lights do seem to have minds of their own)

 

[01EB5.0]

SOunds pretty wierd. DO you have an aux. tranny cooler? Also when was your tranny flushed out last? ALso on the back roads don't you want overdrive on? If it's backroads like I am thinking, it's like 60+MPH and when your going 60 usually it won't not shift out of overdrive unless you hit a large hill? I just got 30x9.5 tires on my truck and it doesn't really have trouble so I would think another inch wouldn't be bad. also what gears do you have?

 

[yob_yeknom]

No, I do not have an auxillary tranny cooler. I have been considering getting one though. I just haven't come up with a good place to mount it. I don't want it in front of the radiator, and don't know how well one would work if mounted inside the frame. I have to keep it from being smashed when off roading.
These back roads are all hills and turns. You basically go straightaway-hill-straightaway-turn... I get just up to 55 and then back down to 35-40. With OD on it does A LOT of shifting in and out of it.
I have 3.55 gears.
That 1" makes a difference. Power and all that is fine, just the tranny is killing itself. On the highway where I have OD off, I like to go 60-65. My speedometer reads 55-60. It shifts like crazy everytime I start up a hill or anything. I really have to work the gas to keep it in OD.

 

[Robert]

No, I doubt if it means anything is wrong with your transmission. Your switch is probably getting close to failing. You pushed it several times without it engaging. After leaving it alone for a while it finally gave in. I spilled some Coke on mine that caused the switch to get stuck in. If your transmission was so hot that the computer needed to keep it in a lower gear to cool off, it would have caused your OD light to flash. It flashes whenever there is a problem with the transmission. I also doubt that you overheated it by driving for 1 1/2 hours with the OD off on the backroads. I pulled a 4000 lb. trailer 2000 miles from Ohio to Arizona with my OD off running from 65-75 MPH without one hint of trouble from my transmission. I think it was a stuck switch or possibly an electronic "gremlin".

 

[yob_yeknom]

Originally posted by Robert
...or possibly an electronic "gremlin".

Curse those evil little boogers!!
I'm starting to think my Explorer is just one big electronic gremlin. It's friggin' crazy!!

 

[01EB5.0]

Well, John, If i were you I'd add an auxilary trans. oil cooler and put synthetic oil in, thatway you know that even high temps will have less of an effect on the tranny. Why don't you want to mount it in front of the radiator and the A/C condensor like it is from the factory? I did for mine and it works fine. I guess the only other difference between your truck and mine is the gear ratio. i have the 3.73 and as long as I go easy on the gas, I can make it up a hill in OD unless the speed drops below 50 MPH.
Also another thing i was thinking of. if you were to make the speedo read the correct speed, then the tranny might have an easier time because it would actuially know how fast you are going. if you were in fact driving 65 MPH and the speedo read that, I'm sure that going upa hill at that spoeed would not cause it to shift, but if it read 55 or 60 and you were actually going 65, then it will shift. I am going to get my speedo recalibrated. I will let you know whats needed to fix this.

Also i would try the switch when the truck is cold. If the switch always works first push when the trucks cold, then i'm not convinced the switch is your problem. I would either try doing the stuff I mentioned above or wait and see if the switch fails in the future. no sense replacing a switch if we arn't sure thats the prob...

 

[mecforyou]

I wouldn't worry about your trany not coming out of o/d one time but if it happens alot
more it's time to look into it. I would install a trany cooler and mount it at the top of the radiator.

 

[yob_yeknom]

I'm a little weary about adding an another cooler in front of the radiator becuase it can get really hot around here and I have done the swiss cheese mod to the airbox. I don't want the engine to run hot all summer because of the radiator being blocked off. I will add one in the near future when I finally find time to.
The button has always worked when the engine is cold. It only happened that one time after some hard on the engine/tranny driving.
By my calculations, one less tooth on the speedo gear will correct my speedo to being only around .01% off. Definitely close enough for me. Just like the cooler, I'll change it when I find time.

 

[Robert]

I doubt if you get any higher than 122F which is what I've seen here in Phoenix. My tranny cooler was mounted in front of my radiator by Ford and I have a K&N FIPK open air filter. The only time temperature was a problem on my Explorer was when my thermostat stuck closed. The air will blow right through your tranny cooler to the radiator. It is a common location to mount it.

 

[yob_yeknom]

Okay, so I'll mount it in front of the radiator.

Which one do you guys suggest?

Any easy way to get in there to mount it, or will I need to remove the grille?