jim2167

When I open the from bow switch the windows go down but the head rests do not, the roof will not open. if I operate the switch for the head rests on the dash they move as they should. just topped the motor up with roof fluid as it was below the min mark. any ideas

JG403

Well, there are a lot of potential issues which cause roofs to fail to operate. You should put this thread on the W209 forum, as the W208 roof is different I'm assuming.


I just went through a whole slew of roof issues with my W208. There is a lot of material on here in regards to diagnosing, e.g. the roof button flashing slowly, quickly, not at all... My hydraulic fluid was low, which was my first problem. tophydraulicsinc.com is very active on here - his website has excellent DIY instructions for getting to the hydraulic cylinders and replacing if needed. My rear bow lock cylinder was leaking... I had more issues after that, but low fluid led me down that path. I ended up fixing all of my issues for about $400, the dealer wanted $7,000...

jim2167

mine is a w208 not w209, do you know if low fluid would stop the head rests from lowering with the roof button but not with the dash button

JG403

Sorry - I could have sworn I saw 209 - my bad. My headrests worked normally...

jim2167

Just been trying again,, manually cycled the roof 5 - 6 times with the pressure relief screw done up, it got harder and harder to move until i could not lift the roof up to close it, so undid the pressure screw closed the roof but not the hatch or rear bow, did the screw up again and closed it on the button including both hatch and bow locking, so the pump must be ok but would not open or close again

JG403

So I had 2 issues - the leaking rear bow lock cylinder and the faulty roll bar limit switch. The first I could diagnose myself - with help I found here. The second was diagnosed by an MB dealer after hooking up the car to their STAR diagnostics.


Check posts on this from Serndipity - he has written a lot on this. The roof opens and closes in a sequence which occurs as switches at the various stages. My problem was the lower roll bar switch - this meant that the controller didn't think that the roll bar had closed all the way, not allowing the next step in the process to occur.


I'm assuming that the switch was the major problem with my roof, the hydraulic cylinder being secondary. That's just a guess, though. Have you checked your hydraulic fluid level after manually cycling the roof a few times? If the fluid level lowered any you would have a good indication of a hydraulic leak.


There is also a relay next to the hydraulic pump that can go bad - I'm not sure what that problem looks like.


When you try and operate the roof with the button what happens to it? Does it blink quickly, slowly, not at all?

jim2167

The relay by the pump is the same as the fuel pump. I have swooped over to check that one. By you description I thing I will try the roll over bar limit switch next. I had a 206cc before the merc and found if I shorted the two connectors on one of the windscreen frame I could get that roof to work. So will try that first I report back

JG403

OK. To get to the roll bar switch you need to remove the back seats... I wouldn't have done that without the diagnostics pointing be in that direction. Serndipity has posted ways to check electronics, as well.

JG403

Also - my roll bar operated as normal. What is your roof button doing when you try and use it?

Serndipity

The first important clue, is that your hydraulic fluid is below the minimum mark.

That indicates that you more than likely have a leak in your hydraulic system and therefore low system pressure.

More then likely, 1 of the 8 cylinders in the W208 power roof system is leaking. Note: Missing hydraulic fluid does not vanish and go the fluid heaven.

See: http://www.tophydraulicsinc.com/diagrams/CLKDiagram.jpg

The usual suspects are the rear bow lock, case cover cylinders or the hydraulic lines located at the hinge of the case cover.

For the necessary steps, see posts 4 through 11 at: https://mbworld.org/forums/clk-class...ps-go-bad.html

BTW, in the first reply to your post, JG403 said that saved a bundle (e.g DIY $400 vs. $7,000 dealer repair). Additionally, his DIY repair also included having several 2 cylinders rebuilt by Top Hydraulics, so the total would have been closer to $10,000 for diagnosis, troubleshooting and shop repair.

JG403

Ha - you're right!

jim2167

No leak found. Only trace of oil was from the pressure lease screw which must not of been fully tightened up. Motor for rear headrest can still be heard after the headrest has got to it's limits both up and down. Rained all day today so had no time to check out limit switch .

Serndipity

OK, you didn't find fluid leakage at the areas that commonly leak (e.g. key an eye open on the level as there are 6 additional cylinders in the system), but now that you have added fluid, you're saying that "Motor for rear headrest can still be heard after the headrest has got to it's limits both up and down."

I've included thumbnails of the N52 RB/Power Roof controller and RB assembly.

Basically, the controller evaluates the inputs (e.g. shown on the left side as well as from the CANBus) and if correct, provides the necessary outputs (e.g. shown on the right side) to operate the RB and power roof system.

The RB has 2 limit switches, S83/5 and S83/6, that should shut off the hydraulic pump when the desired positions are reached.

You can check that these switches are activating properly using a multi-meter (see this link).

https://mbworld.org/forums/clk-class...ar-switch.html

However, there can be other conditions causing the symptoms you're experiencing. As example, the RB uses a single differential (2 way acting) hydraulic cylinder to both raise and lower the RB. If a cylinder seal is leaking, either externally or internally, it may not be raising or lowering the RB enough to reach the limit switches.

The RB/Power Roof is very complex and a suggestion would be to have the MB STAR software check for any stored diagnostic trouble codes, by a qualified technician. The cost should be around $100. Also ask for a print out of any stored codes and that they be cleared (some stored codes can keep the system from operating properly).

Having this information can greatly facilitate a solution.

JG403

I agree completely on the MB dealer tip. I would never have pinpointed the problem without that help.