Howto: Cabriolet convertible top hydraulic system

[Flot]

Wanted to share this while it was fresh in my head. Sorry, no pictures just yet but will see what I can do. I had a hydraulic piston go bad on my convertible top. Turned out to be the one that actuates the lock/unlock mechanism on the "lid" that covers the top when closed. Convertible owners - would highly recommend getting out the manual and reading over the section about how to operate the top by hand. It takes a few minutes, but do it 3-4 times so you know what to do if something ever goes wrong. And DON'T LOSE the convertible wrench that comes in your toolkit - it is a must have for opening/closing the mechanism. Accessing the hyrdaulic system: - Pop the cover that the convertible folds up into. If your system is working, just start the folding process and interrupt. If the system is not working, follow process in the manual. Be very careful when moving this panel as the clearance between it and the trunk lid are tight - trunk must be fully closed to operate - In my case, problem #1 was inside the lid - the hydraulic cylinder in the lock mechanism was leaking. I removed the carpet liner by taking out the 19 plastic fasteners holding it in. - I sent my lock cylinder off to DENNIS FICKEN (mercedescylinders@sbcglobal.net) to be rebuilt. Dennis is a great guy and charges $40 a cylinder to redo them. Dealer quoted me $500 for the whole latch assembly but later I learned the cylinder itself had a part number and probably would have been $120ish. - Removing and replacing the cylinder was easy. Simply unbolt the cylinder, and unthread the metal piston from the lock assembly. To unscrew the piston, you'll need a 9/32 Craftsman Ignition Wrench - that's the only thing that will fit into the notch on the piston without damaging it. (you'll have to see it to understand) The hydraulic lines are held in with clips, just pry firmly outward on the clips and the lines will disengage. Don't lose the clips as you'll need them for the new cylinder. - After R&Ring the cylinder, system still wouldn't work - I had lost too much fluid. Adding fluid was a huge pita. It was clear this could not have been a preexisting problem as it is at least an hour job to add fluid. - To add hydraulic fluid ($22 for a quart at the dealer) you must access the resoviour attached to the pump assembly itself - this is stored behind a solid structural sheetmetal panel at the front of the trunk. - To get to the pump assembly - again, pop the convertible cover and prop the rear window forward and out of the way. You'll be in there for a while. - Looking down, you'll see the top carpeted section, which you can leave alone, and then a row of 7 or so plastic fasteners going the width of the car which hold the forward trunk carpeting in place. You'll need to remove those and then also remove the two 10mm bolts that are holding the convertible safety cover in place. Once you take the two bolts out just grab the roll up assembly and twist it gently to pop it out of position. Remove the cover, the trunk carpet, and the piece of carpet that is covering the front of the trunk. - Whew. Now you should be looking down at a piece of sheet metal that has a good 20 bolts keeping it in place around the perimeter. There are also 4 bolts in the middle - don't touch these - I believe they are holding the stereo amp (?) in place. Take out ALL of those bolts around the outside edge and then slide the large metal panel back a few inches to access the pump. - Now you should be looking down at the hydraulic pump and solenoids. The pump has an opaque plastic tank attached to it, with a threaded fill plug on top. Remove the plug and add your MB fluid (you'll need a long small funnel to do this). There are two lines on the side, low/high fill, fill to high, run the system once to bleed, and then check it again. I had to add fluid twice. Re-assemble and see if you can end up with no extra parts. Like I said, sorry for the lack of pictures, but the job really wasn't too bad just time consuming. The insane thing was just how much stuff had to be removed to simply add hydraulic fluid to the top mechanism. I imagine it would be a 2+ hour job at the dealer.

To remove this ad, register today or login if you already are registered!

[Silverbillet]

Thanks for the write-up. I'm sure lots of people will find this very useful.

[sick430]

this needs to be a sticky

[Missinlinc]

After having a few problems with my convertible top working sometimes then all of a sudden just stop working all together, I came to the forum to see if I could diagnose the problem through some of the other posts on here. My top wasn't doing anything at all, and what really caught the attention of my brother and I was that the roll bar wasn't working either. I tried to see if I could just reset the whole system by disconnecting the battery. That didn't work. Well then I ran across a post by a member named Palm Tree Mechanic over on benzworld where he basically took everything apart and found some bad wires. So we decided that we would give that a try and see if my problem was the same as his. Unfortunately it wasn't but his post did help us A LOT!!! We took everything apart and found no bad wires, hydraulic pump was full of oil, all switches were good, then I sat in the car and started pushing the roll bar button. We heard a click everytime I pushed it. My brother was at the back of the car and was trying to hear where the clicking was coming from. He realized it was coming from a relay switch so he took a screwdriver and tapped the top of the relay and **BAM** everything starts working! So through that we realized it was a bad relay. Went to O'Reily Auto Parts and matched it up to the relay we took out of the car. Then called the local Benz dealership to check the specs on the OEM part. Everything matched up and the dealership said the part was $65.00 from them. Paid $6.00 for a new 30 amp relay from O'Reily and took it home and plugged it in. Turned it on and the roll bar works with no problem. Then tried to operate the top and it worked with no problem! So all in all, it took us a couple hours and $6.00 and everything is good! Hope this helps someone else who may have this same issue!

Here is a picture of the relay. This is Palm Tree Mechanic's picture and I just outlined the relay in green.

[gregory13lil]

DAMN nice troubleshooting!!! I fix alot of my issues as well and its nice knowing you saved a bit of money. It would have costed you the 65 for the relay plus about an hour of labor for troubleshooting $175.00 hr!!

Once again good find.

Greg

[Missinlinc]

Thanks! That definitely would have been an expensive fix if I would have taken it to the dealership! $65 for the part, 1 hr for trouble shooting, and about 3 or 4 hours of labor. We almost got to that point! We checked everything and found nothing. Then just before we gave up, I decided to hit the roll bar button and we found the problem!

I know that's not a normal problem, so hopefully this will save someone else that money too!

[bobbyjo9]

well sorta. I DID take my car in because the top had stopped working along with the easy entry function on the pass seat. The news I got back was shocking to say the least! Quote for the seat was 900 in parts and 800ish for labor. The top was supposedly the controller for 900+ and 900ish for labor with no guarantee that would fix the problem!!??? Thanks but no thanks. Sorry if your going under but im not keeping the lights on for you! Seat motor is 93 bucks shipped and bout 2 hours at a leisurely pace to install. Cocktail break. Top ended up 15 bucks for that stupid relay buried under the plate in the trunk and again.. bout 2 hours at the same pace. Im all about paying a mans wage but lets get real here! I think everyone knows bout the seat motors but for those of us in the cabrios... if you get a slow flash from the button and the roll bar will not go up, swap the fuel relay (next to the rear fusebox) for the top relay(next to the pump) and check operation of the top. If the switch is blinking quickly you most likely have an open circuit in one of the mico switches or trunk lock. Good luck!!

[Zootropa]

I have a 99 CLK 320 Cab. The problems described in the first post are identical to mine.

I took the car to dealership today to see if there was an easy fix. The Service Manager and a tech opened the trunk and messed about for 10 minutes or so. Their opinion was that a relay or micro switch was out of synch or nonop. They closed the car up (its a perfect cab day) and told me they could diagnose the car properly for $143 per hour.

I came home and did a little research and ended up here.

Now the trunk won't open and the top is up.

[Zootropa]

doh, forgot to mention that the top 'stuck' in the up position.

[bobbyjo9]

when you try to lower the top, is the switch blinking fast, slow, or no blink at all? do the windows lower when you release the bow lock?

[Zootropa]

Originally Posted by bobbyjo9

when you try to lower the top, is the switch blinking fast, slow, or no blink at all? do the windows lower when you release the bow lock?

When I release the top, using the turn handle, all windows roll down and an audible hum or whir can be heard, as if the car is mid process and trying to resync or catch up to the process.

The center console top indicator will blink way fast and then more slowly when I start and drive the car.

Driving this car, top down, is the single best tonic I can take.

Very grateful for any help.

[Missinlinc]

Look in your owners manual and put the top in "manual" mode. Then you can continue to diagnose the problem. If the top is not completely closed then the trunk will not open.

[Zootropa]

Thanks for the reply and tips.

I now have the trunk open (as described previously, 15-20 mins of wiggly/jiggly and a bit of WD40 and the trunk opens).

I found a small amount of hydraulic fluid on the windscreen cover (the pull up thingy) and a bit more on a document that I had in the trunk. It looks like the fluid hose attached to the pump is bent and leaking.

I am very sick and would like to drive (when I can) around with the top down, until I can afford to fix/replace parts. My main challenge is that I don't have the soft top tool to manually lower the top.
Ideas?
I am going to try and use a regular open ended wrench.
Apart from that, any and all help is appreciated.

[Missinlinc]

You'll probably need an open end wrench to release the hard cover and a socket to release the soft top. I'm not sure on the sizes since I used the tool that was in my Benz toolkit. You'll also need a flathead screwdriver to switch the pump from automatic mode to manual mode.

[bobbyjo9]

Originally Posted by Zootropa

Thanks for the reply and tips.

I now have the trunk open (as described previously, 15-20 mins of wiggly/jiggly and a bit of WD40 and the trunk opens).

I found a small amount of hydraulic fluid on the windscreen cover (the pull up thingy) and a bit more on a document that I had in the trunk. It looks like the fluid hose attached to the pump is bent and leaking.

I am very sick and would like to drive (when I can) around with the top down, until I can afford to fix/replace parts. My main challenge is that I don't have the soft top tool to manually lower the top.
Ideas?
I am going to try and use a regular open ended wrench.
Apart from that, any and all help is appreciated.

Be careful using any ol wrench there. The proper one is thin for a reason. If you can see the leaking line Im guessing your inspection cover is not in place or missing? Those lines are tiny and wouldn't take much to damage them. If replacing the damaged line and refilling the system is not in the budget.. do yourself a favor and buy the wrench. It cant be that much and without it you run the risk of damaging the top cover paint or upholstery.

[Missinlinc]

Originally Posted by bobbyjo9

Be careful using any ol wrench there. The proper one is thin for a reason. If you can see the leaking line Im guessing your inspection cover is not in place or missing? Those lines are tiny and wouldn't take much to damage them. If replacing the damaged line and refilling the system is not in the budget.. do yourself a favor and buy the wrench. It cant be that much and without it you run the risk of damaging the top cover paint or upholstery.

Very good point!!

[DropTop430]

i have to try to fix mine.... damn cabrio!

[Whodat]

Originally Posted by Missinlinc

After having a few problems with my convertible top working sometimes then all of a sudden just stop working all together, I came to the forum to see if I could diagnose the problem through some of the other posts on here. My top wasn't doing anything at all, and what really caught the attention of my brother and I was that the roll bar wasn't working either. I tried to see if I could just reset the whole system by disconnecting the battery. That didn't work. Well then I ran across a post by a member named Palm Tree Mechanic over on benzworld where he basically took everything apart and found some bad wires. So we decided that we would give that a try and see if my problem was the same as his. Unfortunately it wasn't but his post did help us A LOT!!! We took everything apart and found no bad wires, hydraulic pump was full of oil, all switches were good, then I sat in the car and started pushing the roll bar button. We heard a click everytime I pushed it. My brother was at the back of the car and was trying to hear where the clicking was coming from. He realized it was coming from a relay switch so he took a screwdriver and tapped the top of the relay and **BAM** everything starts working! So through that we realized it was a bad relay. Went to O'Reily Auto Parts and matched it up to the relay we took out of the car. Then called the local Benz dealership to check the specs on the OEM part. Everything matched up and the dealership said the part was $65.00 from them. Paid $6.00 for a new 30 amp relay from O'Reily and took it home and plugged it in. Turned it on and the roll bar works with no problem. Then tried to operate the top and it worked with no problem! So all in all, it took us a couple hours and $6.00 and everything is good! Hope this helps someone else who may have this same issue!

Here is a picture of the relay. This is Palm Tree Mechanic's picture and I just outlined the relay in green.

Wow. This was great information. We cabrios need a 'sticky' for problems with soft tops!

[Missinlinc]

I think this is starting to be a more common problem! Convertible Top problems are very difficult to diagnose.

[LesB3]

Missinlinc,

Next time you are in PA (or I'm in TX), I'm buying you a case of beer. Just dug through the trunk and swapped the fuel relay for the top one and -presto- top works again.

Thanks! You just saved me some serious $$$ at the stealership!

PS I'm trying to find a cheap-o replacement for the relay -do you know which one you got at O'Reilly's? (Brand name and p/n?)

[Missinlinc]

Originally Posted by LesB3

Missinlinc,

Next time you are in PA (or I'm in TX), I'm buying you a case of beer. Just dug through the trunk and swapped the fuel relay for the top one and -presto- top works again.

Thanks! You just saved me some serious $$$ at the stealership!

PS I'm trying to find a cheap-o replacement for the relay -do you know which one you got at O'Reilly's? (Brand name and p/n?)

Glad it helped you out! Sorry I don't have the part number, but I just took my old relay into the parts store and matched it up with one of the relays they had in stock. The only difference was the aftermarket relay doesn't have the small clips on the side! Other than that, it's a direct swap!!!

[Missinlinc]

Mods: can you make this a sticky or put it in the DIY thread. It seems this relay is becomming a common problem.

[LesB3]

Second the request to make this a sticky... I also got a replacement relay at Autohaus (www.autohausaz.com) for $8. The fuel and top relays were the same P/N in my car so you have to search the Autohaus site for the "Fuel Relay" -there's no listing for it under "convertible top."

[eromore@gmail.c]

i've got a huge problem.
kinda like yours, but ... more complex. my top and rollbar stopped working a week ago. so, i opened the trunk, set the top to manual, opened the roof lid, manually closed the top (looked like rain), closed the roof lid, closed the rear top part... and that's where all hell broke loose. i realised the manual and tools were in the trunk, which was closed.

now, the problem is that the top (rear part) isn't closed all the way, so the boot lid interlock is active, preventing me from opening the boot. but, i have to get into the boot to close the rear part of the top. also, at first i couldnt get the key all the way into the lock (the manual one), but jiggling and wd-40 did the job. now, after cca 3h more, my hands are sore, but i still cant turn the key in any direction, i cant close the top all the way (its locked in some midway position, levaing some 1-2inch distance between roof bootom, and roof lid, but it is locked by the top lock on the roof lid, also half way)

it's really a mess and i really need some instructions.

i called local mb, and they told me that they might have to disassamble the whole roof (but there must be another way, but they dont know of it // THEIR WORDS, SUXERS), and that would be about 2k $.

please, any advise would be most helpful.

as soon as possible too... thanks in advance

[big_mike1979]

thank u