tuviking

Hello Fellow MB Owners,

I'm a new member to this forum and I've read so many helpful posts on how to deal with problems with the convertible top. It's about to be serious Cabri weather in Houston and I might just cry if I can't drop that top real soon!

My top had a few stutters and delays the last few times before it stopped working. Now, when I unlock the manual release latch, the windows all go down smoothly and the red light on the button comes on (doesn't blink). When I pull on the button, I hear the faint click (more like a weak almost-click), the overhead lights (the reading lights inside the car right in front of the release latch) dim slightly but noticeably, and nothing else happens. Also, the back seat headrests do not work.

The mechanic I went to says I need a new motor, but did not really explain to me what he did and why he is convinced the problem is the motor. He also quoted $2,200 and some change to replace the motor.

I was wondering if someone in Houston knows of a mechanic who is a master of this problem. I also won't mind ordering a revived motor from Tophydraulics and dedicating a weekend to installing it myself. But I just shudder at spending all that money only to find that I could have replaced a wire or something less complex.

Simply put, I'm quite unsure of how to proceed and I was hoping someone would have some helpful info that pertains specifically to my case.

Thank you so much in advance.

-Tuviking.

Serndipity

At this time, to pay $2,200 to replace the hydraulic pump motor, without a complete explanation/diagnosis is a bit much. Additionally, the motor is no longer available from MB, but can be rebuilt.

TopHydraulics offers a hydraulic Pump rebuild service, including the motor, if needed, for $600.

http://www.tophydraulicsinc.com/en/w...ulic-pump.html

Have you checked the hydraulic fluid level (e.g. there is a flap in the trunk carpet to do this)? Perhaps one of the 7 hydraulic cylinders is leaking and low pressure is preventing the system from completely cycling (e.g. rollbar value).

Additionally, from being a long time forum reader, the motor starting relay has been a very common problem. It's the same relay as the fuel pump relay, which can be temporarily used to eliminate a faulty pump motor relay.

Although I have yet to have any problem with the operation of my power roof, it's not a question of if, but when, it will fail. I just included a spare relay, with the purchase of other maintenance items from autohausAZ (e.g. cost $9 and cheap insurance)

tuviking

Frankly, I'm leaning heavily towards the Tophydraulics solution. I have not checked the hydraulic level via the flap yet. I'll review the manual and check it out. The link you added for the relay led me to an ebay listing for a Honda part. Can one use the Honda relay unit on a Mercedes?

Serndipity

For instructions to check the fluid level, see page 4 in the .pdf at the following

http://www.tophydraulicsinc.com/W208...eplacement.pdf

The link I posted was to the MB W208 hydraulic pump rebuild page, at the TopHydraulics web site. Have no idea how you got to a eBay link for a Honda part.

This is the relay I bought, for a spare.

http://www.autohausaz.com/search/pro...20Pump%20Relay

tuviking

Thanks. There was a hyperlink on the words, "motor starting relay" from your post that is gone now. I think my browser does that annoying thing of hyperlinking buzz words or phrases for commercial reasons. Pah!

But I see the correct one now. Fingers crossed that that's all I need.

And thanks again, bro. This really helps.

Top Hydraulics

Tuviking,

this sounds indeed like a burnt out motor in your cabriolet hydraulics pump. The initial stuttering and slowing down were a first sign of the electric motor having trouble (unless you were low on hydraulic fluid, like Serndipity points out). The faint click would likely be the relay mounted next to the pump. Normally, the problem with these relays is them sticking, in which case they wouldn't make any noise (yet they would still burn out the motor and then blow the 40A fuse). The overhead lights dimming right after the faint click in the rear would indicate that the pump motor is drawing current but not turning. If you were to keep holding the button, you would eventually blow the 40A fuse. Unfortunately, the thermal sensor inside the pump motor is too slow and does not normally make the controller shut off the pump before it overheats.

Serndipity is right on about replacing the relay proactively. Top Hydraulics includes a new relay with the pump rebuild. http://www.tophydraulicsinc.com/en/w...ulic-pump.html

Mechanics with SDS or Star Diagnostics can read codes and tell right away whether the motor has overheated before. If your mechanic does not have SDS, then he can still judge from the symptoms.

The ultimate test without SDS would be jumping the relay and seeing if or how well the pump motor is still turning. Below are pics of a burnt motor and how to jumper pins 30 and 87 on the relay socket.




More details in https://mbworld.org/forums/clk-class...-failures.html.

Klaus

www.tophydraulicsinc.com

Top Hydraulics

DIY pump removal and re-installation is not very hard, only a bit time consuming. That translates into you saving a bunch of money when doing the job yourself (and feeling like a million bucks afterwards...)

Here are some details:

The following part numbers apply:
2088000030 aka A 208 800 00 30 (model years 1998 - 2000, up to VIN -070017 in model year 2001)
2088001048 aka A 208 800 10 48 (model years 1998 - 2000, up to VIN -070017 in model year 2001)
2088000230 aka A 208 800 02 30 (model years 2002, 2003, and from VIN -070018 in model year 2001)
2088001748 aka A 208 800 17 48 (model years 2002, 2003, and from VIN -070018 in model year 2001)

Access to the pump is covered in these instructions: http://www.tophydraulicsinc.com/W208...eplacement.pdf

Once you have access to the pump, do the following:
- unplug electrical connector
- remove socket head bolts on hydraulic line retaining plate
- pull on each hydraulic line individually (do not worry - the lines will all stay connected to the plate, and they will not get mixed up)
- unbolt the mounting brackets from the car, and take out the pump
- drain the reservoir
- remove one or both mounting brackets if you want to save on shipping cost/weight
- put pump into a sturdy garbage bag
- buffer your parcel well inside, ideally double box, and tape up well
- ship to Top Hydraulics after making payment on the website

We ship these pumps exclusively in USPS Priority "Large Flat Rate Boxes", or using your UPS/FedEx account. Remove the mounting brackets before shipping the pump to us, please. Please double box and use plenty of buffering material inside the box.
Top Hydraulics charges $15 for Priority Mail shipping CLK pumps inside the US. International customers, please select "Priority Mail Large Box Int'l" upon checkout. International shipping is described in http://www.tophydraulicsinc.com/en/7...g.html


For installation, reverse the process. Get new hydraulic fluid p/n A0009899103 from Mercedes (1 quart is enough), or order FeBi 02615 online. FeBi 02615 is identical to Mercedes fluid, only it doesn't have a dye in it. You can order it online, for example at http://www.rmeuropean.com/Part-Numbe..._D18BD03A.aspx



Klaus


www.tophydraulicsinc.com

tuviking

Thanks a million to Klaus and Serndipity. It really helps to understand what is going on with one's car rather than just leave it to a mechanic to decide what's wrong and charge whatever to fix it.
I am quite pleased to know that the DIY approach is not particularly difficult. I'll post my results on this thread after it's all done.

Serndipity

Tuviking

Have you had a chance to check the level of your hydraulic fluid and if OK, try temporarily swapping the pump motor relay with the fuel pump relay?

The faint click you're hearing indicates that the current is flowing through the relay's control coil (e.g. pins 85 and 86), which creates a magnetic field that causes a moving armature to close the switch contacts (e.g. pins 87 and 30). However, it does not mean that the relay is good, as the switch contacts could still be faulty (e.g. high resistance).

Specially, the motor draws the better part of 40 amperes and every time the switch contacts transition from either a closed to an open state (break arc) or from an open to a closed state (make arc & bounce arc), an electrical arc occurs between the two contact points. The energy contained in the arcs is very high and destructive to the contact surfaces. Over time the contacts degrade, eventually leading to contacts that weld shut or contacts that fail due to a build up of contact surface damage (e.g. pitting) resulting a high resistance to current flow.

The initial stuttering and slowing down of the power roof indicates that the pump motor was barely getting enough current to operate, until eventually the contact resistance became high enough to limit the current provided to the motor, which is now insufficient for it to start and run.

When dealing with high currents, it doesn't take much change in resistance to mess things up. From ohms law (e.g. current flow = voltage / resistance), in a 12 volt system, 40 amperes of current requires that the resistance be .3 ohms or less. If the resistance increases to 1 ohm, the current flow becomes only 12 amperes.

Alternatively, if the contacts had welded closed, the motor would have continuously run until it burnt up, likely opening up the 40 A fuse.

My 2 cents is that since your dome light still dims somewhat when attempting to operate the roof, the pump motor is just no longer able to draw sufficient power (e.g. current) to start/run.

It's easy enough to verify my suspicion by just temporarily swapping in the fuel pump relay.

Top Hydraulics

I fully agree that testing the relay by swapping it for the fuel pump relay is easy enough. Let's see which version is correct in the end: high resistance in the relay contacts, or the motor windings shorting out. My view may be easily tainted on account of getting burnt out motors in on a daily basis. I have seen at least 100 times more bad motors than relays with high resistance, but that obviously does not reflect the real life ratio of bad motors to high-resistance relays. If the relay contacts created, say, 1 Ohm resistance only for a short time, then there would be a lot of heat created in a small spot. I would assume that either the resistance gets much higher and results in a negligible current draw (not dimming the map lights), or the relay spot welds itself to closed position.

By the way, if someone sends us a perfectly good pump for rebuild with a compromised relay, then we will inform them first before proceeding. Life is too short to be dishonest, and it is more important to us that we help people than making a few extra bucks.

Klaus

www.tophydraulicsinc.com

tuviking

Serndipity,

I haven't had the opportunity to check properly. I've opened up the flap in the trunk but could not really tell what I was looking at. I have been trying to find instructions on how to manually open the soft top. The Owner's manual only discusses proper operation and maintenance of the top.

Also the DIY pdf which looks very helpful only suggests the user refer to the manual for manual op. of the top.

Do you happen to know of any manuals, websites, pdfs, etc. that could show how to manually open the soft top?

Thanks.

Serndipity

Manual operation of the roof is is explained in the Practical Hints section of the owners manual. In my manual it's pages 282 - 288.

tuviking

Thanks a lot. I see it finally. I had been looking in the wrong places. I took a pic of the tools I have just to make sure that I am not missing anything. Please let me know what you think.
Thanks again.