I wasn't going to post yet another boring SMG rebuild thread but since everyone is posting today about SMG problems and we're all geeks that like to analyze things I figured why not.
So Two years ago i replaced my SMG motor and everything was fine till last october I'd get an yellow light on harder driving. Eventually it happened more frequently , for the record I have 91k on my 2010 M5. I'd hear the pump always running blah blah blah. I hooked up INPA and went for a ride and noticed btw shifts pressure wouldn't build then would then wouldn't. I figured it was a seal leak somewhere.
I pulled the tranny and was annoyed at FTE and BMW for the shittacular wires on the sensor strip and decide I'm going to go balls out with a rebuild and it's either gonna work or with boat season coming up I have new anchor and will just bite the bullet and buy the whole unit from BMW. insert typical rebuild story here.
I did decide to replace the internal hydraulic pump seals (Burkhart) , go with the MLR Engineering motor the old one has been working really hard lately, new accumulator because it was towards the end of the range, iirc 29 bar and 28 is the lowest of the range, new seals for all the solenoid( MLR Engineering) and I also went with the Burkhart engineering unicorn piss fluid.
Since I haven't seen a pump rebuild thread I'll say don't be too scared of it, it's just like any hydraulic gear pump or motor. It's all of 10 parts orientation matters but it's not a big deal to figure out if you mess up as it's like any other pump.
What I found though was the internal pumps seals had a crack in it and a few of the shift orings had squared themselves off and were hardened. I assume these were my issues.
The pump runs very little now, the system holds pressures very well, it used to drop like a rock while cruising/sitting but now it barely trickles down and then between shifts when it needs to rebuild it shoots up rather quick.
The attached pic the circled area is where one of the cracks are, and one of the oring what was squared, it's hard to see in the pics Oh well
You have to write MLR for the orings, I actually measured the old ones but decided to go with them since they had them all ready properly sized.
Also big shout out to Rob an MLR, he was very communicative.