JG403

I just wanted to say ugh, and thanks for all of you who have posted thoughts and comments and things to check when good tops go bad. I am now researching through here all of the things to do and check, but I'm not feeling that good news will come. Roll bar moves ok, windows are ok, top button blinks slowly and top wont move... Well, l at least there's a project for this weekend!

Serndipity

At this time, pretty much all that can go wrong with our power roof operation has already been happened and covered in the forum.

When using the forum's search function, after entering some key words, you'll get all the posts that mention any of the search terms, which results in large number of posts, most of which are unrelated to your needs.

I've found using an advanced search, such as https://www.google.com/advanced_search?hl=en , where you can enter an exact phrase and domain will return much more specific results.

From what you have already said above, the first thing to check is the condition of the roof's tension cables.

There are 2 cables (e.g. passenger and driver side), that unfold the joints in the roof's frame, allowing the hydraulic to continue lowing the roof. If the joints do not unfold, because one or both is broken or stretched, further power roof operation will stop.

When you manually release the front bow, the tension they provide, should cause the bow to raise about 10" and stay there, which then opens up the roof frame joints.

If either of the cables is defective (e.g. broken or stretched), the front bow will fall and/or not remain parallel to the windshield frame.

If this is the problem, you can usually open the framework joints by manually pushing the front bow upward.

If the tension cables do not properly unfold (open) the joints in the roof framework the power roof will not open, but it will close OK.

If your cables check out, alternatively, post additional details of your symptoms, being as specific/detailed as possible, as to the point of failure etc.

JG403

Thanks for your response! So... I didn't see cables that appear damaged - but I'm basing that on bot seeing any. If i turn the car on, with windows and roll bar up, disengage the roof - Windows go down, roll bar didn't. Roof button is solid red. If I lift the button, there is no sound, snd nothing happens except the button blinks slowly.

JG403

So, the hydraulic fluid is very low..

Serndipity

Thanks for the additional clarifications (e.g. roll bar not lowering and very low hydraulic fluid level).

After you unlock the front bow, the windows should lower (if previously up), the roll bar should lower (if previously extended) and then the rear bow should unlock (see attached .pdf).

The lamp associated with the main power roof switch provides some basic diagnostic fault conditions, which are explained in another attachment.

Your roof failure at stage 1 is most likely due to low hydraulic system pressure, which is caused by a leak somewhere in the hydraulics. The most common culprits have been seal failures, in either the rear bow lock or soft top case cover cylinders.

In the W208 section, at the following link, you find an excellent DIY instructional that explains the access to and replacement of these cylinders.

http://www.tophydraulicsinc.com/en/c...y-instructions

JG403

Thanks! I printed the instructions for accessing the pump and will do this also. Looks like a weekend project... It looks like with this these good directions and patience I can do this work? I really appreciate the help!!

Serndipity

At this time, to visually check, if either the rear bow and/or case cover cylinders are leaking, because your hydraulics are currently not operational, you'll need to manually unlock the rear bow and case cover.

The instructions of how to do this are in the practical hints section of your owner's manual.

Given the amount of fluid loss shown in your picture, you likely will find fluid pooling within this area. Closer visual inspection of either cylinder, only requires the removal of some carpeting.

JG403

I can't thank you enough! I had done a lot of research, but you really helped cut through it to get to what I need!

JG403

Holy cow - I have been trying to manually unlock the bow to start the process for 30 minutes. I have the tool, but can't find where to, er, stick it...

JG403

Apparently you need to post, walk around the block swearing to yourself, then it works!

JG403

Leaking rear bow lock is the guilty party...

Serndipity

JG403......Great and thank you for the followup.

Fortunately, your DIY skills, in quick order, found the problem and saved a ton of $$$$!

Other than the MB roadsters, during the W208 area, our cabriolets are rarities and will return significant return on investment $$$$, when properly maintained.

That said, now that you're past the PITA part, gaining access to the power roof components, I would also suggest taking care of some other common failures in the power roof, such as having the case cover lock cylinder rebuilt along with the rear bow cylinder, as well as replacing the pump motor relay (a $10 part).

JG403

Thanks - I would never have dreamed of tearing into this project without the help you and others have given me!

I will definitely do those other items while I have it all torn apart.

Thanks again!

JG403

The disassembly is finished. Now on to Top Hydraulics for new cylinders... Interestingly, I stopped by a MB dealer outside of Cleveland for hydraulic fluid and they also recommended them... I'll also order a new relay. Anything I'm missing?

JG403

Special thanks to Klaus and Top Hydraulics for sending along the cylinders and locks. And for the replacement hydraulic line clip I dropped somewhere in the trunk!!

JG403

Thanks Klaus @ Top Hydraulics! The roof project continues this weekend...

JG403

Ok - got everything out together, manually set the roof in to the boot. Now it won't work with the button and I can't lift it manually! Any idea?

Serndipity

You should still be able to operate the roof manually.

Operation of the power roof will be blocked if the luggage compartment cover is not properly in place. Make sure that the roller wheel is activating the limit switch, located in the right side track (see thumbnail).

When the trunk lid is unlocked/open, the soft top cannot be operated because of the possibility of a collision between the trunk lid and the lid of the soft-top compartment cover. The power roof controller checks that the trunk is closed via communication on the CANBus.

The hydraulic cylinders operate in differential mode (e.g. 2 way acting), depending on which side of the rod pressure is applied and may be out of kilter. There is a subsequent locking procedure to correct 'when the soft top is not completely locked at the end of it's operation.

For this purpose, press the main soft top switch in the direction 'open soft top' (if the top is open) or in the direction 'close soft top' (if the top is closed). When you do this, the controller will only operate the hydraulics associated with the case cover, rear bow and RB (if it's not completely retracted). Each actuation should take about 5 seconds. Also, make sure that the pressure relief screw has been turned back to restore full system pressure.

Lastly, there have been situations after replacing a cylinder, where other power roof limit switches are out of synch and need to be reset. As example, S84/15 Soft top fabric bow up/down limit switch, S84/5 Soft compartment cover open switch etc. The procedure to re-synchronize them is to fully open and close the roof manually.

JG403

Thanks! Klaus came through - idiot me didn't release the pressure. I'll check that everything's put back in place, open and shut it manually a few times, them give it another run.

I really appreciate the help!

JG403

So here's what's happening... I opened snd shut the roof a few times manually, then closed everything up. The pressure valve is closed.
If I start the car and try to raise the roof, the windows and roll bar work, but nothing else happens. The roof button light is lit, stays lit, but does not flash.

JG403

I can't hear the pump running for the top. I tried to open the and close the roof from different places and nothing. When I try to use the button from here the button flashes slowly but nothing happens.

Serndipity

The causes for the flashing lamp are explained in the thumbnail enclosed in post #5.

What condition applies?

Just above, you mentioned that the RB works OK (e.g. hydraulically moves).

The N52 controller is fused in 3 places, have you checked each of them?

Another possibility is that the controller may not be getting the required electrical signals indicating that the rear bow or case cover have not been properly locked.

This can easily be checked out, with a multi-meter to measure the resistance (ohms), by disconnecting the N52 connector, manually setting the roof to a prescribed stage of operation and reading the ohms between specific connector pins and ground. This will verify that the electrical circuits, from the switch and wiring to the controller are OK. More details on this later.

JG403

I've been googling and searching for 40 minutes to try and find a diagram for this fuse box. Any ideas? Also, could this relay be a problem? I've ordered a new one that sits by the hydraulic pump.

JG403

Picture

JG403

Of course I found it right after I posted this