Everything Working Now
Well, my replacement o-ring fix lasted all of two days
It was worth a shot anyway, and it gave me experience removing the valve block and removing a solenoid valve, plus I got a know a good independent mechanic in my area that works on Mercedes, so it was a net positive!
I decided that I was just going to get a rebuilt valve block from Top Hydraulics, which for $200 is a great deal for me since I don't have a lot of spare time these days to keep removing my rear seats, cleaning up the mess of hydraulic fluid that squirts out form a leaking value, and then trying to track down an o-ring that fits. Klaus sent me out a rebuilt block, I removed my old block, installed the replacement, and after connecting the hydraulic lines properly, everything works now - roll-bars and top!
I did have a slight brain-fart and connected the metal lines up to the wrong ports initially, and couldn't get anything to work. Klaus was very helpful troubleshooting with me over e-mail and what the problem finally turned out to be was that for some reason unknown to me, I connected the lines in such a way that the roll-bar stop lines were connected to the ports for the roll-bar cylinder, and vice-vesa, so the system was fighting itself whenever I turned on the pump. Fortunately I had taken pictures of the correct arrangement, and after going through all kinds of troubleshooting including making sure the new solenoids were getting 12V and the coils were good, and making sure the pump was pressurizing the supply line to the block (warning - if you try this, put a wad of paper towels over the end of the line or you will spend the next week cleaning up hydraulic fluid that sprays all over the inside of your car, fortunately I did use the paper towels so didn't have this problem!). So, I took out my phone, looked at the pictures of the old block, and slapped my forehead for being such an idiot. Oh well, live and learn. Connecting the lines correctly made everything work. First I lowered the roll-bars and then opened the top, and raised it, and all went smoothly.
Throughout this whole process, Klaus was fantastic, from shipping out the block quickly to helping me troubleshoot the problem. When it's time for my cylinder rebuilds, I'm going to order them from Top Hydraulics.
One thing that I had a problem with while I was troubleshooting was that my roll-bars had stopped in the raised position, and I used the manual top opening method to try to raise the top, but it wouldn't go past the rear headrests. I had my daughter try to help me manually lower the roll-bars by pushing on both of the brass release plates and pushing down on the head rests but even with both of us pushing, we couldn't make them move. I wonder now if the problem might have been that the pressure in the cylinder was too great and I should have disconnected the hydraulic lines from the cylinder (or block). Given that I had the lines backwards, and even though I released the system pressure using the release screw on the pump, the vales in the block were probably configured to prevent the hydraulic fluid from moving since the cylinder was connected to the roll-bar stop ports.
Anyway, it was all a great learning experience and my first foray into anything hydraulic (other than the really good glass of wine I had after it was all working
So, replacing the valve block is really easy, and, assuming you connect everything up properly, you can do the whole operation in less than an hour. Here's a quick guide to how to do it, Klaus also has some detailed instructions that he can send you if you need them:
- Release hydraulic pressure in the system by turning the pressure release screw on the hydraulic pump two turns counter-clockwise. You access the screw from inside the trunk by pulling up the carpet material at the back (you don't need to remove the large black metal plate).
- Remove the rear seat.
- Take a few pictures of the valve block so you can refer to them when you install the new one.
- Disconnect the electrical connections to the solenoid valves. The red-marked connection goes to the right solenoid value.
- Remove two nuts from behind the valve block.
- Remove the two black plastic hydraulic line clip keepers; you'll need these when you install the replacement block.
- Move the two clips to the left. They click into each position.
- Remove the hydraulic lines. Have paper towels handy since they might leak and you might get a squirt of fluid from the lines and/or the ports in the block.
- Unscrew the hydraulic line from the right side of the block. Same note about paper towels.
- Remove the old block.
- Reverse the procedure to install the replacement block. I like to screw the block into the bracket as a last step since it makes inserting the hydraulic lines into the ports in the front of the block easier if you can move the block around a bit.
- Close the pressure release screw on the pump, and add hydraulic fluid if necessary. Some people recommend a flush. In my case, the o-ring leak did the flush for me all over the rear of the back seat so I just added fluid. Note that you have to use the Mercedes OEM fluid or the approved replacement. The dealer charges about $20/quart for this, my dealer gave me a discount because the parts guy says he always gives a discount to people working on their own cars.
- Move the roll-bars up and down, make sure there are no leaks.
- Open and close the top, make sure there are no leaks and that it operates smoothly. I have read that the first few times after refilling a dry system, there is air in the system which will automatically bleed out, but you'll notice that the top may slam down hard on the windscreen frame when it's being closed. Catch it with your hand so it doesn't damage anything.
And that's it!
Attached is a picture of my old valve block; the one that Top Hydraulics sends is virtually identical to this.
