The little Liftgate pump that couldn’t?
 

I have been through a lot of ups and downs with this liftgate 😩 and I appreciate everyone who alphas helped me over the years.

I believe I have replaced pretty much every part in the system And it was working for some time but it recently started messing up. first the shop said the fluid was leaking out so they topped it off. Then the reservoir cap somehow partially came off so the fluid leaked out again. I put it back on and filled it up but it’s still not working.

In the video you’ll see that IF it works (which happens sporadically) it will not lift all the way. I have confirmed is NOT the setting that limits how high it is raised. I just don’t know what else to look for except a new pump.

I would appreciate any help or insight anyone could provide!

Did you replace the two gas shocks? If you apply a little upward pressure to the gate as it raises, will it go all the way up? Don't use so much as to completely lift it - you just want to try and "help" it to figure out if the shocks are worn out.

I'm not sure on that sound, but to me it sounds like air in the system - but I would think it should self bleed. Can you track down the sound better? Are you still losing fluid? If you're losing fluid, that's likely the problem since the pump won't be able to build as much pressure as it should. If it's not external, then there could be seals on the inside that are shot - I can't say for 100% how it's built inside, but I'm my experience with boatmotor power tilt pumps as a comparison. Now, IF that's the case, I don't know if that pump is rebuildable - boat pumps are - but I honestly have no clue on the gate pump. But maybe it's something you can check into.

I just replaced my struts with the manual version from an ML and called it good.

it opens automatically and closes manually and that’s all I will ever ask of it.

are the gas shocks the things the actually move the door up and down? I did replace those…they came with the last pump! I know the noise is coming from the pump for sure

The struts are the two black things you actually see on the left and right sides of the gate - they assist the hydraulic arm.

Listening to your video again, I think if it was the gas shocks, the pump would continue to make noise and "strain". Instead, it sounds like the pumpjust stops - like it's being electronically stopped. That seems like a programming thing. Might need to pay someone that knows how to do STAR/DAS programming.

I agree with Dennis on this, the noise sounds like air in the system. Recheck your work since the fluid may have worked its way through the lines. Inspect the pump and the line connections for leaks. Loosen the reservoir fill screw to release any air, add/remove fluid if required (do not overfill; make sure the fluid is level at the "+" mark on the reservoir), then reseal.

As for the liftgate height adjustment, try this:


or this:

thanks for sharing that…if there is air in the line is there directions or a procedure to bleed it?

Now I’m being told that it’s the arms or the mechanism connected to the pump that’s keeping the liftgate from operating properly…

is that possible?

Yes it has to be aligned. If for any reason it’s out of alignment it won’t close properly and the door will just open when it tries to shut itself.

That may be what they’re referring to. It’s also possible to bend some of the hardware in there if you’re too rough with it.

it opens and closes correctly when it does…my problem is it doesn’t always open when the button is pressed…when I try to actuate it with my scanner it doesn’t work

It doesn’t open all the way either only half way

I'm still having issues with the lift gate. it doesn't respond when I attempt to open it and close it when i got the scanner hooked up. It doesn't respond to the key and every blue moon it will respond to the door button. I would love to know what bleeding the lines looks like.

Update: I filled the pump with oil (it was empty for some reason) and tightened the screw pretty tight.
i used the button on the drivers door to open the liftgate. It only opened halfway. I pulled the button again and it went all the way up.

it’s been working good so far.
if it acts up again I’ll change the pump and reassess.
Thanks to all that helped!

You might consider converting to manual liftgate. I find the power system worse than manual - it's slow! - and actually raised the liftgate into a ladder on the roof rack when my son was afraid to stop its progress. One large scuff in the paint, and I wish the power system had never been installed at all.

well that was fun while it lasted...about 1-2 weeks is pretty common...I am starting to have issues again...I'm noticing the fluid is lower so its leaking somewhere. the box and spongy stuff is always wet but is where somewhere else that I can look to see if it is leaking? I'm thinking maybe the pump reservoir is bad.

Clean everything up REALLY well with degreaser/brakleen. Then monitor VERY closely/often to find the leak. You can get creative with taping pieces of paper towels in key areas (and/or higher areas) as it will help to narrow down if the leak is high/low.

I appreciate the idea...that make a lot of sense...but can you tell me some points to put the paper towel?

I know you have the actual pump reservoir
you have the place where the wires connect to the pump
but from there I don't know where the wires go and the possible places that can leak

The wires won't leak - follow the hydraulic lines. At this point, you just need to know if it's leaking somewhere there by the motor or it's hydraulic line connections... or somewhere along the hyd line (cracked) or higher. Narrow it down to a general location, then focus closer and closer to the specific point.

Put a folded shop towel on the subwoofer.
any leaks from the piston hidden behind the ceiling liner will usually puddle there.

thanks I will see what I can find out.

great idea...I will do that right now...
should I take the pump out of the box so that I can see if its leaking there? The spongy stuff is all wet but I don't know if that is from before or not

Hi, I have gl550 2010 with same sound as your lift gate. Opened up was fine, but came down halfway then went back up.
Tried to replace new hydraulic fluid, but no help.
( pump maybe too weak) Next..
I thought the position sensors was bad and I bought used set ( pump, position sensors …etc complete set) from eBay, made an offer $100…(check to make sure clean and good condition , no water corrosion….)
I was lazy and did not want to remove many panels to change the whole set, and tried to replace pump Only.
Bam, working good after replacing only the pump.
Good luck with yours!!!

https://cimg7.ibsrv.net/gimg/www.mbw...26ac6cbbad.png
Bought complete set, but working after replacing only Pump.

I'm thinking replace the pump also. what is the rest of the stuff attached?
how much did the pump run you?

I got an offer $100 ($199 the original price ) from eBay. Only used Pump, the rest i keep it for future antique parts😂

the motor for the pump is available online around $30, but I didn’t not want to spend more time incase not a motor

https://cimg5.ibsrv.net/gimg/www.mbw...4b8ec0336.jpeg
#1 i think hydraulic piston to absorb movement ( up and down)
#2is hydraulic shock to pull up and down rear door #3 is positioned sensor ( adjust the height)

wow that is a great deal! I have a guy offering me one for $150

are there any differences between the pumps out there?