pjw6619

Hi,


Can anyone please advise me how to re-set the roll bars/headrests on my 320 CLK Avante Garde Convertible 2001.


I have had to close my roof manually, with the headrests/roll bars stuck in the highest position. When pressing the Roll bar/Headrest Button on the dash board for 8 seconds plus, as I understand it, this should re-set the roll bars/headrests.


I can hear the pump/motors running, but the roll bars/headrests will just not move down at all. Have had a mobile mechanic visit me today and after doing a diagnostic check etc, there are no fault codes showing on his laptop and everything is fine.


According to this technician, you cannot manually re-set the roll bars/headrests by any other way on this model?


Your answers will be very much appreciated. Thank you in advance!


Peter

Serndipity

I believe what you tried was the subsequent locking procedure which is explained in post #18 at http://www.benzworld.org/forums/w208...ertible-2.html

However, if you hit a big bump, pot hole, were doing doughnuts etc. the roll bar is spring loaded and can mechanically activate, independent of the hydraulic system.

In this case, lowering (e.g. resetting) the roll bar has to be done mechanically.

I recently read a post on how to do this, but didn't bookmark it.

Basically, the procedure was to insert a tool (e.g. a screwdriver, rod?) down the side of one of the headrest, which released a locking mechanism and then pushing down on the roll bar.

FWIW, post 10 and 11 at https://mbworld.org/forums/clk-class...umps-help.html describes another approach.

pjw6619

Hi. Thanks for your reply. Apparently, the roll bars on the W208 model (which is my one) cannot be manually released in the same way as the W209 by inserting a rod down the side of each roll bar, but thank you for your reply and links which I have read with interest.

Serndipity

Twenty five or so years ago, convertibles almost became extinct, due to rollover safely issues.

The solution was adding rollover bars, which MB has been using since. Since it's possible to mechanically activate to roll bar (e.g. when hitting a pot hole, bump etc.), I find it implausible that MB has not provided for a method to mechanically reset the roll bar on a W208.

BTW, while it seemed like a lot of effort, the person in the link I provided above, was able to reset the roll bar on a W208 (e.g. 2002 CLK430).

Have you tried asking a dealer shop foreman or a country/regional MB tech support specialist?

Top Hydraulics

Folks, excuse my ignorance. I don't own a CLK. I have heard from a number of customers that you cannot reset the roll bar manually on some W208s - I believe it's the newer model years. However, isn't there a way to do it hydraulically? It would be utterly ridiculous if this couldn't be done with the pump. What does the owner's manual say? Isn't there a way to do it by holding up the roll bar button for several seconds so that the pump can extend the hydraulic part of the system and let it catch up, such as in many other cars?

Klaus

www.tophydraulicsinc.com

pjw6619

Have been told by Mercedes Garage that the only way to release the headrests if the dashboard button method fails, is to strip out all the rear trim and seats.

Apparently, once this is done, access to the rear headrest springs can be reset manually. It's a lot of manual work just to do this. The Mercedes Garage quoted a labour charge of £175 per hour. The job will take 3 to 4 hours to do.

My headrests/roll bars locked up when I was closing the roof whilst stationery, which has never happened before. I've had this car for 6 years and never had a problem before.

pjw6619

Hi Klaus,

The way to do it hydraulically is to press the roll bar button on the dash board for 8 seconds in the 'up' position followed by pressing the roll bar button in the 'down' position, however, although I can hear the pump working, the roll bar/headrests fail to go down!

Serndipity

Per the owner's manual:

"The roll bar will automatically raise in an accident or a potentially dangerous driving situation. A ratchet noise can be heard when the roll bar is automatically raised."

Comment: The automatic raising of the roll bar is done independently of the hydraulic system. There are compressed springs that release, raising and locking the roll bar in an up condition. Automatic roll bar deployment can also activate from large pot holes, bumps or accident avoidance maneuvers.

"The roll bar can be lowered again after an automatic deployment by pressing the upper half of the roll bar switch (for at least 8 seconds) until the roll bar drive mechanism audibly engages. Then press the lower half of the switch to lower the roll bar."

Comment: OP states that this procedure did not work.

I also found another potential solution (see attached description of a subsequent locking procedure).

Basically, if the soft top is not completely locked at the end, the roll bar may not completely retract. The procedure involves exercising a subset of the hydraulic system to lock the soft top compartment cover and rear bow.

If this does not restore normal roll bar operation, I do know of an instance where the roll bar was successfully mechanically reset (see link below). Unfortunately, it's a pretty ridiculous and a PITA procedure.

https://mbworld.org/forums/clk-class...umps-help.html

For a full description of the W208 roll bar mechanism, see post #4 at:

https://mbworld.org/forums/clk-class...f-problem.html

GatorMB

There is another instance of the roll bar spring lock mechanism failing.

The dealer repair was in the $500.00 margin. and the fix was welding which I would not recommend.

For this fix I would go for salvage.

Gator

pjw6619

Hi Everyone,


Following on from my problem with my soft top, I managed to get both of the headrests/roll bars down (with a friend) by sitting on each headrest, whilst pressing the button on the dashboard!


Hoping and thinking that this would rectify the problem, it hasn't unfortunately!
With both headrests/roll bars in the 'down' position and the soft top up, I pressed the soft top release/open button on the centre console (by the gear stick).


What happened was that the soft top did not operate at all, however, the head rests/roll bars deployed slowly once again (ratchet sound).


So I am no further forward and back to the original problem once again. Has anyone got any ideas or explanation as to what they think the problem is please?


I look forward to hearing from you,


Regards,


Peter

Top Hydraulics

Could be internal bypassing in the roll bar valve 1248001678 behind the rear seat, left lower corner.



W208 roll over bar valve located in the lower left corner behind the rear seat

The roll over bar ratcheting up slowly without being prompted to is a typical symptom for a bad valve A124 800 16 78. An internal bypass in the valve will release the lock pawl on the roll bar, plus it robs the cabriolet hydraulics of most or all pressure. There is rebuild service and core exchange available, if this valve should be the problem. More details here:
http://www.tophydraulicsinc.com/en/w...d-service.html



Location of the hydraulic components in W208 CLK320 and CLK430


Klaus

www.tophydraulicsinc.com

GatorMB

This sounds like a logical explanation with the function but we need some diagnostic input as well. The mechanical side needs an inspection, when the headrest fail to return it is noted that broken parts were found in the floor which were welded to fix.

Folks never weld a safety device or spring rated metal as failure is life eminent.

It will take some skill to test the control valve that Klaus is showing. I am glad he is in the house so to speak as these cars can get ugly to diagnose over the internet.

Thanks Klaus for added input.

Gator

JackRobinson

So did you remove your seats and re-set your headrests?
I have the seats out but can't find how to re-set the roll bar?
Thanks, Jack

Serndipity

After RB crash deployment, if the reset procedure as described in the owner's manual as well at http://www.benzworld.org/forums/w208...-position.html using the RB switch / hydraulic pump doesn't work, apparently the RB can be lowered manually as described here http://www.benzworld.org/forums/w208...ion-motor.html .

In summary, associated with each head rest is a locking pawl, that swivels into the gear rack and locks the RB in place. It's shown as item 4 in the 'crash deployment.pdf' included in post #32. Apparently, by inserting a long screwdriver down into each of the head rest areas, you can un-swivel each pawl and push down the RB, followed by resetting the fault codes.

Just passing this on as an FYI (READ: procedure at your own risk).

JackRobinson

This was very helpful in helping me locate the release latches. Going to try to post a video to help others as it was a long search to find them
Thanks, Jack
No apparently you can't post a short video here.

JackRobinson

After finally locating the manual release for the roll bar I am surprised how mine actually move. All I've read says to locate them and push them down. Mine definitely move towards the back of the car or trunk, straight back. There is no pushing them down.
I have removed the seat to get a better view.
Another bit of information I've read here repeatedly; the headrests operate independently.
I've submitted a picture and it is obvious there is one solid bar from left to right connecting the headrests. I can't see anyway they could operate separately. I believe I will need one person on one side pushing the release back and the headrest down as I do the other. How can these be two separate pieces when they are one piece? I just don't see it.
I will post a video on you-tube showing the release of the pawl lock, titled; "roll bar manual release pawl lock 2003 clk" And more to come..
Jack

Serndipity

Jack.....thank you for the excellent and valuable additional information.

For once and for all, the ongoing mystery of how to lower a W208 roll bar, stuck in the extended up position, has been solved.

Please refer to the 2 enclosed thumbnails, which detail and explain how the W208 roll bar works.

You are correct, the roll bar in the W208 is constructed as one single unit, which is shown as item 1 in the diagram. Also note that there is a synchronization bar present, item 30, that follows the rack pinions to keep the roll bar from canting when the roll bar is deployed by the springs.

However, when this occurs, there are 2 separate locking pawls, located behind each head rest, that swivel into the gear rack and lock the extended roll bar in place.

The first thing to try, to lower the roll bar, is the method described in the owners manual, that uses the hydraulic system. Basically, hold the roll bar switch in the up position for about 10 seconds, until you hear a click, which is the locking pawls releasing, followed by then lowering the roll bar using the roll bar switch.

If this fails to lower the roll bar, it can be lowered manually.

This is done by inserting a long screwdriver down into each of the head rest areas, you can un-swivel each pawl, followed by gently and evenly pushing down the roll bar.

However, as Jack pointed out, just pushing down on the pawls will not release their locked condition (e.g. the pawls must un-swival to an unlocked position), which is done by applying pressure around each of their pivot point.

Although I've yet to have the pleasure of having to lower an extended roll bar, once the 2 locking pawls are manually released, you might then be able to lower the roll bar hydraulically with the main roll bar switch. I would try this first, to avoid canting while lowering the roll bar, but it's not clear whether or not a fault has to be first cleared.

Lastly, once your roll bar has been lowered, if your power roof fails to operate properly, I've enclosed a 3rd thumbnail that explains a 'subsequent locking procedure' that MB provided to help restore power roof operation. It's possible that the power roof/roll bar controller had become confused (e.g. out of kilter or synch) when the roll bar became extended. Specifically, note the last bullet point, regarding exercising the roll bar value block to re-synch to rod/piston side cylinder operation as well as the roll bar extended/retracted micro-switches. No guaranty....but it's like chicken soup......won't do you any harm and may do lots of good.

GatorMB

Bump, Serendipidy is awesome

JackRobinson

What does "canting" mean, while lowering the roll bar?
Thanks, Jack

Serndipity

It means that both sides of the roll bar move evenly, without an angle to one another (e.g. not tilted or slanted).

JackRobinson

Yes, I finally located the lock pawl or pawls; one on each side. However it hasn't helped any as far as lowering the roll bar. I was able push or swivel the lock pawls back and wedge a screwdriver between the mechanism to hold it open or unlocked; however I am unable to push the roll bar down. They don't budge. They are still locked.
I read another thread here from "tonydr00" posted in May 2013. He mentions something about a motor being unhooked and 4 ball bearings falling into place and so on.
It sounds like that might be what I need to do but I'm unclear of the exact procedure.
If anyone can assist I would be very thankful.
I've removed the back seat. I sent the roll bar valve to TopHydraulics, that wasn't the problem.
I hear a click or pang type of noise when I push the roll bar button on the dash. I wonder what that is? Thanks, Jack

Aussiesuede

Jack, just in case, I'll ask. Have you released Hydraulic pressure prior to attempting to lower the headrests after manipulating the pawls?

And that clicking sounds like the relay. Try unplugging the relay and see if the sound disappears to confirm.

JackRobinson

I'm glad you asked. No I haven't released the hydraulic pressure? Don't know how.
Can you possible direct me to a thread or explain to me how to do that?


As far as the clicking noise and unplugging the relay? Would that be the red and black wire going to the roll bar valve?

I apologize for my stupid questions but I'm not at all familiar with this. I'm just trying my best to save some money. I've put a lot of money in this car over the last two years; new transmission, catalytic converter, radiator and more. More then it's worth and I can't justify spending thousands on the roll bar issue or top problem.
Keeping my fingers crossed I"ll be able to solve it on my own for a few hundred; lol..
I appreciate any help.
There seem to be many people here with a similar issue but not a lot of clear information and lots of conflicting info.
Thanks for reading my thread, and any and all help.
Jack

Aussiesuede

Hi Jack. Hydraulic pressure is released by inserting a flathead screwdriver into the white cone of the pump circled in blue in the above picture.

The pump relay is just to the left of that white cone circled in red in the picture above. You simply lift up on the relay to unplug.

In theory, once you've relieved the system of hydraulic pressure, you should be able to have someone push down on both headrests at the same time whilst you manipulate the pawls. Once you've successfully retracted the headrests to the down position, reinsert a screwdriver into the white cone to re pressurize the hydraulics. Again, in theory, your headrests should then be operational via the dash button.

JackRobinson

Hi Aussieusuede; thank you for the great information. This has been a long search for correct information.
Thanks to you and a few others, I think I'm getting to the resolve. I'll post the final results of this thread.
Sincerely, Jack