Transmission Overdrive

[Brad01]

93 Explorer with 140,000 mi the transmission seems to be slipping in and out of overdrive the transmission fluid and filter were changed less then 2000mi can any give some insight on this issue.

 

[DDehnke]

I have been told by sooo many people not to change the trans fluid with high milage, it creates more stress on internal parts. Your reverse will prolly go out next. My O/D is out right now and on the 3 transmission that have gone out on me it was only a few thousand after i changed the fluid on them. Look for a rebuilt trans.

 

[MrShorty]

93 Explorer with 140,000 mi the transmission seems to be slipping in and out of overdrive the transmission fluid and filter were changed less then 2000mi can any give some insight on this issue.

Is it really slipping, or just randomly shifting from 4th to 3rd gear (or alternatively, since many can't readily tell the difference, locking and unlocking the torque converter lockup clutch)? If it's just shifting when it shouldn't, but not slipping, check the wiring to the shift solenoids. Your A4LD has two: 3-4 shift solenoid and TCC lockup solenoid. Wiring problems in those two circuits can cause random "shifting."

 

[WizardOfOdds]

This may sound like a stupid question... but what does it mean exactly when your tranny slips... or gears slip... or whatever

 

[MuscleJunkie]

I have been told by sooo many people not to change the trans fluid with high milage, it creates more stress on internal parts. Your reverse will prolly go out next. My O/D is out right now and on the 3 transmission that have gone out on me it was only a few thousand after i changed the fluid on them. Look for a rebuilt trans.

Why does it create "more stress on internal parts"?

 

[DDehnke]

Think, over the past 16 years of its life it has worn down the fluid, its no longer as thick as it once was, then when you change it its back to thicker fluids. Thats what made it make sense for me when they were trying to explain it.

 

[MuscleJunkie]

Think, over the past 16 years of its life it has worn down the fluid, its no longer as thick as it once was, then when you change it its back to thicker fluids. Thats what made it make sense for me when they were trying to explain it.

What about using synthetics?

 

[colecifer]

For a long time I did not understand why changing the fluid could be detrimental until recently when I heard what seemed plausible to me. If the transmission has not been well maintained over its life then there could be excessive wear in the transmission and lot of metallic junk in the fluid. The little bits of metal at this point could actually be providing the friction that is making everything work. Putting in new clean fluid and flushing out the little bits of metal then remove that friction and cause problems.

I have 183k on my car. I don't think it was well maintained before I got it, but I changed the fluid anyways. My gasket was old and I figured it was not gonna last much longer. Once I got it off I could tell it was only a matter of time before it started leaking. I changed it and haven't had any problems yet.

 

[UKExploder]

Most transmission shops will tell you to change the fluid and filters every 25k miles, but if it has never been done, it will only inevitably make a high mileage tranny start to screw up and soon quit working........end of story....it just happens that way....I even had a tranny specialist tell me the same thing I just said........he didn't have an explanation, and the only type of work he did was automatic tranny repairs....

 

[MrShorty]

In response to your email:

Thanks for the info on the slipping issue. My next question is where is the shift solenoids, 3-4 shift solenoid and TCC lockup solenoid?

The shift solenoids themselves are in the valve body. The wiring to them is strung all over creation.

 

[BrooklynBay]

Some other factors could create a lack of overdrive such as a bad VSS, BOO switch, TPS, overdrive solenoid, clogged screen, or bore, and faulty wiring intermittently touching the transmission case.