When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
CLK 320 Convertible Top Troubleshooting - Fluid Leak and No operation
I have a new to me 2004 CLK 320. Car belonged to a friend and had not been driven much the last 4 years. It has always been stored indoors and is in generally good shape.
I have been able to operate the soft top several times since purchase, but it would stop mid operation and I would have to hit the switch again to get it to finish. I discovered the fluid was a little bit low so I ordered proper hydraulic fluid from Amazon and filled it up. I tried to operate the top and the fluid level dropped again so I added more and tried to continue to properly fill / bleed the lines. After about 4 cycles of this, the fluid continues to drop and the top quit working. I could get it to open windows and release the top, but would not proceed further. I can hear the pump running, but no movement with the top.
Prior to my ownership, my friend had it checked by the dealer and they noted "Error in convertible top operation – believe limit switches in top of windshield frame are not in adjustment or failed." I had not had any issues with operation other than fluid level, so I suspect the limit switch problem is intermittent.
I believe I have 2 problems. Limit switches in top of windshield and a hydraulic leak.
Limit switch - I can hear a click on the passenger side limit switch when it is depressed. I don't hear a click on the drivers side. Do I need to replace this switch or could there be an adjustment issue that I should look at first?
Hydraulic fluid leak.
I believe my fluid is so low the top operation won't do anything at this point.
I have removed seat bottoms and don't see any fluid below back seats.
I have inspected visible hoses and cylinders in trunk area.
The only leak I can find is near the pump. I have circled the locations in red.
I would sort out the hydraulic issue first before the switches.
Is there a way to set up a camera with flashlight in the trunk to confirm this is where the fluid is leaking from during operation.
For mine, it was a faulty RH main cylinder that was leaking onto the base under the rear seat pad, combined with a broken switch under the tonneau cover.
I didn't set up a camera, but I did try to clean off some of the suspect areas. Then I wrapped in paper towels to see if I can identify / confirm the leak here.
The top was in down position so I tried to raise it using hydraulic system.
It was able to complete the first stage and raise the compartment cover lid. But it didn't proceed after that. I was able to lower the compartment cover lid, but it asked me to open the ski bag partition first. I did that and proceeded to close the compartment cover lide. It didn't occur to me at the time this limit switch for the ski bag partition may interrupt the closing sequence.
I then looked at the condition of my fluid and paper towels.
Paper towels are completely dry, but the fluid had a substantial drop. This seems like a massive leak and I have added about a half bottle of fluid at this point. I would think this is making a huge mess somewhere that should be easy to find, but removing back seat side trim pieces doesn't look fun. With how much fluid I have added, I would think it would be visible by removing seat bottoms. No visible leaks under the car. Can I look somewhere with an endoscope? Is there somewhere else I should be looking? Is it safe to assume I need to check all locations that have a cylinder and check both sides to see if there is either a hose or cylinder problem?
If you haven't already been there, visit the Top Hydraulics site for all things convertible top, including how to remove all the interior panels
They say that the two main cylinders are the first to go as they are doing the literal heavy lifting. Which was the case with mine. I had emptied the little pump tank a couple of times and while I did find some below the seat, some more had been absorded by a pad behind the side trim and some may have ended up in the gap between that and the outer skin. But it didn't feel like around 1/2 liter of fluid.
TH recommend refurbishing all the cylinders together, which makes sense, but is also >$1000. My RH main was leaking, so I did both as the amount of diassembly is basically the same. $400 for the pair R&R from Top Hydraulics.
EDIT - I should add that with the tonneau cover open, but the top still stowed, you should be able to reach the tops of the main cylinders and feel if they are wet with fluid.
Last edited by DangermouseCLK; Sep 26, 2025 at 08:13 AM.
I feel pretty certain the main cylinders are the problem. I had seen the TH videos, but was skipping through them to see an overview. I just watched the one to replace main cylinders again and early on in the video, Klaus said the chassis can hold a lot of hydraulic fluid without spilling to the ground. I am ordering cylinders today and will return the cores after they are replaced. I'll update after I get this step done.
When you watch the TH video about removing the side panel, be sure to read the comments too as someone points out two screws under the windscreen clip (if that's what it is called - the screen that can be installed behind the seats to reduce buffeting, if you have it) that need to be removed, that Klaus doesn't mention in his video....
Was able to change out the mail lift cylinders. I expected the process to be more difficult, but Klaus has great videos and it went smooth. Top is operating again without any leaks. Thanks to Dangermouse for your assistance.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
