I'm going to preface this by telling you that I don't know much about automatic transmissions. I've mostly owned manuals.

About 2 weeks ago, my torque converter on my transmission stopped locking into overdrive. Normally at 60, the engine would run about 2,000 rpm and then it would run 2,200-2,500 to maintain speed. I got the truck home and changed the fluid. I put in some fresh Valvoline Dex/Merc and a bottle of Lucas oil transmission no slip. Truck seems to be working fine. Locks into overdrive.

Again tonight, the converter will not lock up in OD. The first time this happened was on the same route I drove tonight, which is all highway and slightly uphill.

Possibly related, but not sure, is that when the transmission shifts from 2nd to 3rd, it's not smooth and the tach dips suddenly and then goes back up to "normal" RPM.

The transmission has 268k miles on it and as far as I know has never been rebuilt. I've owned the truck for a year and put only 8k miles on it in that time.

Any thoughts would be appreciated.

It seems difficult to find parts for this transmission (such as solenoids). I'm thinking a rebuild is what is going to be needed but know that is going to run into some serious money. I would love (LOVE) to do a manual swap, but do not think I am ready to take on such a task.

 

Just got my first AT recently so I wont be much help there.

What I would suggest if the transmission is failing - not real far fetched possibility given the miles - would be to swap one it. I routinely see your transmission on craigslist for $200-500 which is less than paying someone to rebuild it.

 

did you ever fix this issue mine is doing the same thing ?