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This was a helpful thread to know what to expect, so I felt obligated to share some of my observations and photos:
- I tried prying the hydraulic strut off the ball, but was to the point I thought I'd damage the tailgate frame. A single tap with a mallet and block of soft wood - off it popped. I did spray penetrating oil first.
- The ball stud had little wear (9.91mm diameter versus the new one at 9.95mm) despite being original (body color paint on the ball stud) and the E61 having 135k miles
- I removed the hydraulic strut from the tailgate end, which gave more room to work with
- After cleaning both hydraulic strut sockets I packed them with some BMW sunroof grease, but then noticed I could NOT spin the retaining ring. After finally getting it to rotate in a complete circle, more black debris came out and contaminated my fresh grease. Lesson here is to use a pick and spin the retaining rings to dislodge the debris. I suspect I would wear a grove in the new ball stud if this was still frozen in place.
Just to clarify, you never actually remove the retaining rings? You just tapped the arm off the socket, put a new ball in, fresh grease, and shoved it back on?
kd7iwp, correct - I did not remove retaining rings on either end of the hydraulic strut. I eventually got the retaining rings to spin in their groove, which dislodged more debris.
I went out tonight to get after this problem and the tailgate would not open much. On inspection I found the body end of the hydraulic strut pushed though the wire hole. It is very stuck so I'd like to remove the tailgate end of the strut which is resisting even with a little prying and hammer tapping. Any suggestions as to how to get it off without significant collateral damage?
I have a 2008 E61 535xi with the same problem… thanks for all the posts!!
I got a replacement OEM ball pin and reshaped a worn knuckle and the power lift is working well.
The new pin install was easy. I cleaned out the knuckle that fits over the ball and noticed that the pressure of the door over the years had deformed the cup where it sits on top of the ball, so I expected I’d have the same challenge others have reported where the piston continues to slide off the new ball. I decided to try and restore the original shape of the cup and the lift has been working perfectly for the past month. (Sorry, I didn’t take pictures so I’ll try and describe clearly.) I removed the piston from the car at both ends…it was still connected to allow the hydraulics to work…and I propped the tailgate up with a sturdy floor broom. I laid a folded up towel over the rear of the car so I could futz with the piston without scratching the paint. Then I tried a couple of approaches to restoring the original shape of the cup. What ended up working the best was a regular hammer and fine nail set tool. Because the metal of the knuckle/cup is relatively soft (why it deforms in the first place), I didn’t have to strike hard at all…I put the piston on the towel against the car and then placed the fine point of the nail set against the knuckle/cup metal that was raised where it had been deformed. I struck the nail set lightly with the hammer, and then moved the position of the nail set slightly and struck it again. I repeated this process a bunch of times and was able to restore the cup to its original shape. When I was done, the metal at the side of the cup was no longer raised…it was flat with lots of small divots from the nail set. I applied white lithium grease to both ends and then attached the piston to the ball pin on the tailgate first. It was difficult to get the other knuckle to fit on the new ball pin attached to the car. With the towel protecting the car, I used a mini crowbar for leverage to apply pressure against the piston and it slid right back on. after a month of regular use, this solution is still working very well.
This approach was inspired by using a dapping block to shape metal. Metals can be heated with a torch until they are super hot…this anneals the metal, aligning the molecules and making the metal soft so it can be shaped. As the metal is hammered, the molecules change positions and over time the metal becomes stiffer and harder to work. It seems possible that reworking the knuckle/cup metal the way that I did may have actually stiffened it so that it will be less likely to deform again. At least I hope so.
Originally Posted by Stuboski
Well, I got the replacement ball pin installed. I put some silicon grease on it, and reinstalled the hydraulic cylinder. I pushed the cylinder on as best I could, and it seemed as if the ball was fully seated into the knuckle. I lowered the tailgate, and hit the button to open it again. The hydraulic cylinder promptly came off of the new ball pin. I used as much force as I really wanted to with a handy bar to pop the ball pin into the knuckle, so if the ball is not all the way in, then I don't know what to use to press that on there. If I do have it on all the way, then the knuckle must be worn out as well. Is there any way to replace the cup that's inside of the knuckle, or am I looking at a brand new hydraulic cylinder?
I attached a photo of the old ball pin to show how worn out this part is. Looks like it has two grooves worn in it. Anybody have any ideas on my next step? Thanks!!
I've been searching for a way to get my automatic hatch from popping off on opening with a new ball pin and the key was to clean out the hydraulic lift to ensure the retaining clip can move freely.
All it really took was some WD40 to clean out the lift and some needle nose pliers to reshape the opening a bit and make sure the pin could move freely. I put some silicone grease in the hole and it easily set back on the pin when I could reposition the clip so the opening was facing down before pushing the ram back onto the pin. I feel like the freeplay of the retaining clip is often missed on a few other attempts to fix the lifter, so if you're having the same problems this is the right approach to give you a long lasting fix pretty pain free.
09-16-2020, 03:37 AM
