Possible slipping

[rgcanfield86]

Hey folks, dont get on here much, but you guys seem to be able to diagnose pretty good s I figured I would ask.

First I have an 01, Expy with 5.4, auto tranny and 4x4. Just moved and towed a 3500 lb trailer from PA to GA. No issues until about 3 weeks later when I noticed at around 45 - 50 mph it felt like the tranny was slipping when in overdrive. If I let off and thn lightly step on gaas the vehicle shutters like the tranny is slipping.

Took to the dealership and they looked it over and test drove it. Couldnt find anything wrong. Since then I feel it almost everytime I drive, but if I take off the overdrive I can drive all day with no issues. I have to driveto NC this weekend and tow another trailer about 1500 lbs back home to GA and dont want to blow my tranny for something silly. Anyone have any ideas.

No warning lights, enginge running fine, no vibrations, no clunking noises, etc. Just the feeling of slipping in overdrive. Thanks

 

[hwy73]

How many miles on truck? Has trans ever been flushed? Might be time.

 

[rgcanfield86]

Only around 114k on it and it hasnt been flshed since I have owned it (2 years now). THe dealer said everything looked fine with it, but my thinking was that or a vacuum problem somewhere since it is only in OD at lowere RPMs.

 

[97_edition]

Only around 114k on it and it hasnt been flshed since I have owned it (2 years now). THe dealer said everything looked fine with it, but my thinking was that or a vacuum problem somewhere since it is only in OD at lowere RPMs.

Mine is started doing the exact same thing about a month ago. Taking OD off it feels fine. I mainly notice it keeping the speed limit as you described (in OD letting off the gas then just giving it a little bit). I took it to the garage and they said they couldn't find anything wrong. I was told by a friend it sounds like a vacuum leak as well but we have yet to find it.

Let me know if you find the problem and I'll do the same.

Oh, I had my transmission flushed a little over a year ago and it made a noticeable difference in shifting, especially the lower gears. I had around 120,000 on mine when it was flushed and now the odometer is 126,000.

 

[rgcanfield86]

Well did some research and found a garage that gets great reviews. They tested everything and found that the Torque converter was shot and not engaging and that the OD gear was also slipping. Needless to say, the tranny is getting worked on right now as I dont want it to get worse.

From my understanding the torque converter engages at 42 mph which is why it only showed up around 45 mph or so. He thinks that the OD just had too much stress on it from the TC not working. Will hopefully get lucky and not have to have more fixed than that. He did say that it is good that I caught it now and stated that it would get much worse the longer I let it go due to the TC being gone.

Will update this when it is finished so others can benefit from it.