Hey, everyone. I just fixed a tailgate problem that I thought would be worth writing about. My wife and I bought our family a 2006, 530xi sport wagon earlier this summer and it started having problems fully opening the tailgate when it got cold this winter. On top of that, the pump seemed a bit noisy altogether when we got it. I did a bunch of looking around to get information, and decided the problem was most likely a pump low on fluid. I opened up the rear/left side compartment and sure enough the bottom was sticky, under the pump was sticky and you could see a pinkish film on the bottom of the pump assembly. The fluid level was definitely low and I decided I would tackle the job of filling it.
I found a number of recommendations online and the best one seemed to indicate a couple hours worth of pain in the butt to unscrew the bracket with the whole pump assembly, fill it upside down and go through a whole process of adjusting the level until things were right. Well, I came up with a MUCH simpler process that I think would take about 30 minutes now that I can provide a parts list and straightforward procedure.
First, you need to gather the following parts. A can of Royco 756 oil, a marinade injector, two sections of 1/4" tubing and a 2" hose clamp.
Attachment 620909
Open the tailgate of the car, open up the left side panel and pull back the inner lining reveal the pump and the reservoir. Notice that it has a non-reusable clamp holding the reservoir to the pump. Use a pair of wire cutters to take off the clamp. I grabbed one edge and just opened it up. Now you can use a plastic tool to pop the reservoir off the pump body.
Attachment 620910
You can then use the marinade injector with a small piece of the tubing on it, to suck out any oil left in the reservoir. Once the reservoir is empty, you can just tilt it and slide it out WITHOUT REMOVING A SINGLE MOUNTING BOLT FOR THE PUMP ASSEMBLY!! 
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With the reservoir removed, carefully put the longer sections of 1/4" tubing on the two siphons sticking out of the pump body. Notice how the one on the left (closer to the main pump body) has all the air bubbles? That is the overflow. Put both hoses into an empty container and close the hatch. That will drain out any fluid left. If any comes out of the pickup hose, drain out the line. Now leave the overflow hose in the dirty oil container, and put the pickup hose into a container filled with plenty of hydraulic oil. You will now cycle the liftgate open/closed a few times. It will refill with fresh oil and you will get extra coming out of the overflow, creating bubbles. Cycle as many times as necessary to make sure the overflow has fresh oil in it.
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The system has now been primed and is ready to be refilled and closed up. Take off the pieces of tubing from the pump and slip the reservoir under the pickup/overflow tubes. Let the reservoir rest flat on the panel below the pump, and there is enough gap between the edge of the reservoir and pump to slip in the end of the 1/4" hose. Fill the reservoir with fresh oil, using the injector. I added 53cc of oil, but I think that was a bit much. I recommend 50cc instead. When you have added the oil, just carefully lift the reservoir up and clip it back onto the pump.
Attachment 620913
Finish by securing the reservoir with the new, reusable screw clamp and you are done. Close everything back up and revel in having refilled the pump so quickly and easily. If you refill and it leaks out again really quickly, then your pump might need new seals. When I was researching the pump issue, I came across a web site from someone who can rebuild our pumps for $300. http://www.tophydraulicsinc.com/en/b...gate-pump.html From what I see on my pump, I bet rebuilding is just a matter off popping off the square plate at the bottom of the pump and replacing a bunch of O-rings.
Well .... hope this post is helpful to some of you out there.
Jose
Jose
