Post #29 in this thread contains my solution. It still holds up perfectly fine. A new ball-bolt is a must in almost every case as the old one tends to wears out. Post #27 shows pictures of worn and new ball-bolt.

 

OK I saw that and I did purchase a new ball just in-case. It may hold up a bit longer since I wasn't able to fully tighten the ball and line it up with the pin. So right now the ball may be rotating as the door moves up and down and the pin may survive.

 

Back to square one

That said, has anyone replaced the hydraulic arm? Is there a DIY somewhere? Seems like a pretty big job. I think I may bite the bullet and order a new arm (part 51247163662) which really, really sucks since the one I have on right now works fine, minus the socket being so worn that the ball won't stay in. How much time would it take for a shop to do this job? I would tackle it myself if it wasn't frigid out and if I had a better garage.

 

I've been quoted about $1,400 to replace the whole arm and hydraulic thing inside the car.

I've also been quoted around $500 to replace the arm with a regular non-motorized arm.

 

I'm also thinking of having it done because I want to replace the rear windshield (scratched up bad); and the defroster doesn't work. Figure since they'll have the rear door off, it would behoove me to just get everything fixed so it all works 100%. The only other thing I want checked out is how hard it is to open the rear glass. Shouldn't it rise on it's own once I lift the latch? Mine is super heavy and has to be raised all the way to the top or it cracks my head. I understand that that mechanism lies within one of the door hinges.

 

Has anyone bought a used product from these guys?

AUTO PARTS LOCALWWW.AUTOPARTSLOCAL.COM
5220 Bullock Point B 103 Colorado Springs, CO 80919

888-524-4105 Ext 104
(Direct Number 720-408-0907)
Customer Service 844-305-2677

I put a request in for a used hydraulic arm for the rear door (~$900 new) and they got back to me within 15 mins to tell me they had the part for less than $200. Calls, text and an email. Scam? I find it hard to imagine that they found it so quickly but could just be paranoid.

 

So I bought a new ball joint and still had the issue of the arm popping off. I decided to spray some WD40 into the receiving socket on the arm and after 30 mintues came back to attempt mounting the arm to the ball joint, and click... it has worked like a charm since. Fingers crossed that the 12 dollar part and some WD40 will hold up for another 9 years!

Good luck for all of you that have had this issue. Hoping more are like my situation.

 

I read in a german forum that you can use Mercedes part# N071805013302 to replace the snap ring.

 

I've had the same problem of the hydraulic strut popping off the ball for several months now. Yesterday I finally got around to making the repair - I decided to try the set screw method suggested by Stuboski on page 2 of this thread. I shopped around, found some stainless steel ball tipped set screws that I thought might work nicely and roll a bit on the ball. I did a short post here on how I did the repair:

The Fix-it Blog - Sorting Things Out: BMW 535xi Touring E61 Tailgate Hydraulic Strut Popping off the Ball Joint - Set Screw Repair

I set the set screws a bit loose so there is enough play for the strut to move around a bit as it closes - but it positively locks the strut to the ball - it can't pop off any more.

 

Forget all this nonsense, I'm putting a manual arm on the drivers side and am DONE with this stupid ball and socket.