My 2001 F250 has 302,000 miles. Within the last 1,000 miles I've noticed random harsh upshifts between 2nd and 3rd gear. These seem to be increasing in frequency and harshness. All other functions are completely normal.

When the transmission is cold, they are only slightly noticeable during gentle acceleration, sometimes with some hesitation. Occaisionally the harshness is not present at all duing moderate acceleration. It are most noticeable at high RPM/WOT when everything is warmed up.

I have verified that the shifter and shift cable are operating correctly and there has been no apparent damage to the switch at the transmission, including inspecting the connector for corrosion and I've checked the two #30 torx-head screws above the steering column which were tight.

The fluid is full and so clean it is hard to see on the dipstick. It does not smell burned. I installed an aftermarket inline filter years ago, and have used Baldwin B252 filters.exclusively since then. I changed the filter and it appears there are some metal fragments in the pan I drained the filter I removed into. I will "test" these particles with a magnet today... I have not removed the pan from the transmission, but I suspect a failed or failing clutch disk or disks, but don't know if there is another possible problem or problems, nor do I know if a failed disc can be diagnosed without tearing down the transmission.

Am I on the right track here? Would a "pressure test" reveal anything that will help with a final diagnosis, or does the fact that all other functions are normal eliminate a possible pump issue?

Any input will be appreciated.

 

If it were me, I'd start looking for a reman or a core that I could have rebuilt. That's a lot of miles and IMO it's about time for a change-out.

 

Read the codes. They may point out a problem.

To read them I recommend Forscan. You can download it free at www.forscan.org. You don't need to buy a license to read codes.

 

I have had no indication of a code, neither a CEL dash light or the flashing OD light on the shifter. My code reader did not show any codes, including while driving, and experienced the harsh 2-3 upshifts. It indicated nothing. My code reader has read a P0720 code (output speed sensor circuit failure) in the past, so I'm pretty sure it should read other transmission codes, but I am not 100% sure of that. I have access to a more sophisticated code reader and will try it as well, when get my hands on it in a day or two.

I ran a magnet through the fluid and the "sparkly stuff" I saw in the fluid stayed in the pan. The filter is inline with the cooler. There could be ferrous metal in the transmission pan, I haven't dropped it yet.

My driving style is pretty gentle on the transmission 99% of the time, but I do pull a 7k lb. travel trailer in the mountains and the transmission gets a work out then.

 

I would suggest downloading Forscan as Mark K advised. I'm no expert, but most generic code reader are capable of only reading generic codes. Manufacture codes exist and are only available through certain channels. My code reader is a tablet style machine that requires regular updates that you pay for. Worth it, even at my amateur status.

Probably not related, but past GM transmissions would begin to fail like this. A failing clutch pack or drum band would get weak and the transmission would compensate for the slip by increasing the fluid pressure. The failing set would feel normal, but the "good" clutches would shift very harsh. Again, it may not be related at all.

 

I'd really love to upgrade to an alumaduty, but it sucks they went from the 6R140 to the 6R100 for the gassers. Sure the 140 is overkill, but I'd rather have overkill.

 

I've downloaded Forescan and ordered the whip so now I am playing the waiting game until the whip arrives. I am due (mileage wise) for a fluid change but I won't waste that expense if I'm going to have to have the trans rebuilt.

When I researched the P0720 code I mentioned before, I found several stories where a transmission shop sold someone a rebuild or remanufactured transmission before checking the circuit itself, which made the repair an expensive, time consuming mistake that could have been prevented by cleaning corrosion from a plug and connector. Not for me, especially with Mark's expertise and the other knowlegable help on this site available!

 

Since your fluid is clean and full, I would suspect a valve body issue. Do you experience any slipping in the second or so after the gear shift?

 

No slippage, but sometimes a hesitation before the clutches engage. But that's really rare.

 

I just recieved the OBD link cord and will connect and read any codes on Tuesday. Visiting family until then.

 

Six weeks later (hunting season and a failed u-jint on the front drive shaft)...

Hooked up Forscan and pulled codes. Only code was P1876, I find NO reference to any transmission issues with that code. FTE and other sites suggest this code is triggered by the ESOF Pulsed Vacuum Hublock Solonoid. Confirmed by the pinpoint test in my manual. The vacuum line to the hubs is plugged due to a leak in one of them and that quite possibly is triggering the code.

The shifting issue has actually gotten better, happens less frequently and does not seem to be as harsh but it is still there...