First post on the forum but long time user of all this advice.

Cutting to the chase, just replaced the filter and fluid of my 2010 R56 non-turbo auto trans.

After leveling the car, I drained it, changed the filter, buttoned it back up, filled it cold, warmed it up, topped it off with fluid warm and engine idling.

Now, trans shifts harder than before, over-revs, and makes this horrendous buzzing noise.

Anybody have this before or have any insight on what it may be?

The fluid I put in amounted to what I pulled out, so I can’t imagine it’s that far off but who knows?

 

Any transmission or other fault codes?

What specific ATF did you use?

How did you add the ATF to the transmission?

What ATF volume did you add?

At the end, did you verify the ATF was at the correct level in the transmission using the service manual procedure?

If all above is fine, one possibility is that the transmission adaptations need to be reset and relearned.

 

https://www.northamericanmotoring.co...sion-flush.pdf

I was using this tech data to service it and do the final check at temp, added fluid from the back of the trans right under the power steering servo.

I threw in the Mobil 3309 fluid.

Ended up draining 3.7 L from the trans and put 3.7 almost exactly back in after doing the drain plug procedure.

No codes yet after driving it around town.

What’s the process for resetting the learning?

 

Was transmission shifting poorly/harshly prior to this work?

Did you assume that the ATF was at proper level in transmission before you drained the ATF and replaced the filter?

After adding new ATF, did any new ATF spill from drain plug with engine idling and ATF temperature at 35C - 45C (95F -113•F)?

You would need a BMW/MINI scan tool to reset and relearn transmission adaptations.

 

I had a little spill out once the temperature came up to 40C, and I screwed the plug back in when it changed to a drip. Not assuming it wasn’t low before, just that what I took out happened to be what I put in by following the procedures, which seemed reassuring.

I had a few hard shifts now and then before the change, but now every shift is rough and there’s quite a buzzing noise coming from the trans.

 

How many miles were on the old fluid and on the transmission?

There’s a belief that if the fluid has been neglected long enough, changing it will lead to shifting issues because the dirt and wear particles in the fluid are providing the friction necessary to keep the worn clutch packs working. If this is the case and it were my car, I would make sure the fluid level is correct, reset the adaptations, and drive the car to see if the shifting improves after the TCU makes its adjustments.

If the transmission doesn’t have an issue due to neglected fluid, I would do at least two more changes with short drives in between to mix up the fluid. The 3.7L you got out with a pan drop is a little over 60% of the fluid capacity. Without a pan drop, the amount is around 2-2.5L so the the total amount of new fluid should be around 80-85% after the three changes.

Also, the temp of the fluid should be within a specific range when checking the level. The 2nd gen cars, unlike the 1st gens, are supposed to have a transmission fluid temp readout available in one of the diagnostic modes on the tach or speedo.

 

https://www.northamericanmotoring.co...ll-method.html

 

I’ll try and find someone to reset the TCU and see if it can relearn the patterns then.

The car has about 130k miles on it, and I have no clue how often the trans was kept up. Hopefully they serviced it somewhat regularly as needed.

If it doesn’t change anything, then I’ll see if cycling out more of the fluid can make a difference.

I’ve been using the temp readout from the OBD, but it sure would be easier to just switch into a screen on the tach. I’ll have to look into that!

 

I wouldn't bet on it. This very well could be the car's first ATF replacement.

 

Hopefully it’s been changed, otherwise it looks like I’ll probably be into a trans rebuild here eventually.

After driving it some, the trans is shifting great now. It is, however, still making the horrendous bussing noise at idle in reverse and drive (but not neutral or park)

 

Good luck. Hopefully resetting the transmission adaptations along with a relearning period will lead to further shift improvements and noise elimination.

 

I'm not quite sure you did the fill quite right. Here's what I'd suggest:

1) With the car fully cooled down, add more fluid. Like probably half a quart. Reinstall the plug on wherever you're using as a fill port
2) Jack up the car level and start the car. With the car running open the transmission drain plug
3) If you get some fluid out move on to the next step. If not, turn off the car, add more fluid, and go back to (2)
4) Use an instant read thermometer to measure the fluid temperature. It will continue to dribble out as the transmission heats up. Once it reads 95F renstall the drain plug (use a fresh crush washer)
5) Turn off the car only after installing the drain plug, then you're done

(Also, you are sure you still have the plastic riser installed in the drain hole, right?)

 

This is the procedure I used to fill and drain the system. Sorry if my previous posts were confusing. I guess the only difference is I went up 5C higher than 95F (35C) but still within the recommended temp and used the OBD readout instead of an instant read thermometer.

I do still have the riser installed, as I pulled it to drain the old fluid, and I installed it (in one piece) before I added fluid.

I’ll throw in the difference in temp and thermometer when I do the next fluid change to filter out some of the old stuff that’s still in there.