W124 power seats – how to remove the seatback rear cover? - PeachParts Mercedes-Benz Forum

Jeremy5848 · #1 02-04-2009, 07:00 PM

I put this thread here in Diesel Discussion after searching several forums including our DIY section – Diesel Discussion gets the most traffic, perhaps someone will be able to help.

The driver's power-adjust head restraint in my '87 300D Turbo (W124, OM603) has never worked. When you press the switch, you can hear the motor quietly running but the headrest does not move. I assume this is some kind of cable or gear problem. All of the other functions of the driver's power seat work including memory. All of the functions of the passenger's power seat (including the head restraint) work.

The head restraint motor sounds like it is in the backrest somewhere, probably under the back cover, but I don't know how to get the cover off of the seatback. If I can get at the motor, I can probably fix the problem. The CD-ROM version of the FSM gives instructions for only the manual seats, not for the power seats. There are a couple of screws at the base of the cover at the rear of the backrest and I removed them but there seems to be something else holding the cover on. Suggestions?

Jeremy

daw_two · #2 02-04-2009, 07:25 PM

Quote:

Originally Posted by Jeremy5848

I put this thread here in Diesel Discussion after searching several forums including our DIY section – Diesel Discussion gets the most traffic, perhaps someone will be able to help.

The driver's power-adjust head restraint in my '87 300D Turbo (W124, OM603) has never worked. When you press the switch, you can hear the motor quietly running but the headrest does not move. I assume this is some kind of cable or gear problem. All of the other functions of the driver's power seat work including memory. All of the functions of the passenger's power seat (including the head restraint) work.

The head restraint motor sounds like it is in the backrest somewhere, probably under the back cover, but I don't know how to get the cover off of the seatback. If I can get at the motor, I can probably fix the problem. The CD-ROM version of the FSM gives instructions for only the manual seats, not for the power seats. There are a couple of screws at the base of the cover at the rear of the backrest and I removed them but there seems to be something else holding the cover on. Suggestions?

Jeremy

Pull down ....gently and FIRM.

cphilip · #3 02-04-2009, 07:51 PM

Someone else here, and I forget who, told me that the problem was likely the plastic clips that hold the rod to the, erm... contraption (I still don't know what it looks like) that the rod attaches too right behind the seat just below the headrests. I can feel them in there through the seat back. But would indeed have to remove the seat back to get to them. Appears it is tucked in on each side. But you might want a set of these clips before you do. Appears a struggle will ensue. Both on but then again more off.

My 95 E320 has this problem as well. They probably have become detached from the mechanism that drives them up and down and, reportedly they are joined/attached by some sort of plastic clips which can break.

Thats all I know so far. I have not dug into it more than just that superficial account that as relayed to me. Feel free to correct me if this is wrong.

babymog · #4 02-04-2009, 08:11 PM

There is a small plastic spring-loaded clip, the button of which can be pressed in the soft spot in the seatback to properly release the headrest from the power drive.

Very common for these to be broken or disconnected. If the headrest will rise with the mechanism, but not go down, you might just need to push the headrest down into the clip.

If the clip needs replacement, they're a pretty small part and I hope pretty inexpensive, I'd order a pair before digging into the seatbacks.

The seatback has screws across the bottom, four phillips I believe. Remove these.

The next step is easiest with a helper, I've done it alone but easier with a helper:
The sides of the seatback are molded with a groove in them. The seat side fabric/leather/tex has a hard plastic sewn into it, which is folded, wrapped around the ends of the seatback, and inserted into this groove. The tension of the fabric helps to hold it in place.

With a helper sitting in the seat, pressing his/her back into the seatback to create slack in the side fabric, run a smooth tool such as a #1 phillips into the bottom opening of the seat fabric where it meets the seatback. Pull the tool toward you as you slide it upward, pulling the fabric rearward and out of the groove. Repeat on the other side.

Installation will become obvious, note that the fabric is folded once before insertion. Again a helper to press back and slacken the fabric on the sides makes this process much easier.

Jeremy5848 · #5 02-04-2009, 08:11 PM

Quote:

Originally Posted by daw_two

Pull down ....gently and FIRM.

OK, it moves a little but still seems stuck somehow. . . does the armrest have to come off first? (FSM doesn't give instructions for that either.)

daw_two · #6 02-04-2009, 08:36 PM

Quote:

Originally Posted by Jeremy5848

OK, it moves a little but still seems stuck somehow. . . does the armrest have to come off first? (FSM doesn't give instructions for that either.)

Nope. It should be quite snug on the sides and top. Almost EVERY w123, w124, and w126 seat that I've taken the back off.....was TIGHT.

Just make sure you get BOTH screws out. As I recall, the w123 only has one.....but my memory is a thing in the past.

sixto · #7 02-04-2009, 10:47 PM

In my 87 300D with factory leather seats, the back cover is held on by jaws in addition to the two screws along the bottom. This is in contrast to 126s and 140s I've worked on in which after removing the two screws, a little downward pressure will release the back cover. So in the 124, or at least my car, the back cover has to be pried outward from the jaws. There's no way the cover will slide down and off the seat.

This site shows a 140 view of the headrest mechanism. The 124 mechanism isn't much different -

http://www.v12uberalles.com/power_head_rest.htm

In couple of three headrests I've repaired, the problem was the clip that retains the barb at the bottom of the left headrest post which required replacing the entire track. I haven't seen the problem described in the 140 site.

I've heard of the flexible drive cable coming off or fraying.

Sixto
87 300D

Bio300TDTdriver · #8 02-04-2009, 11:13 PM

There are two screws on the bottom of the seat back see pictures. Once those are removed, you can slide the hard plastic back off. It is very tight, it's been on there for 20 years. It will slide down if you really want it to. Once it is off, you can check the function of the headrest. You do not need to remove the armrest, unless you want to remove the entire upper seat cover. The third picture shows the clip that the headrest arm snaps into. If you can get your headrest all the way up, you push in a release to remove it.

I have the Mercede$$ource seat repair book. If you want to borrow it let me know. If you want higher resolution photos, let me know and I will email them to you.

You may need to remove the 2 plastic trims on the side of the door side of the seat as well. If you do, be very careful with the upper one, as at his some fragile plastic tabs on the front of it.

curlytom · #9 02-05-2009, 12:20 AM

Found a couple of threads that may be of further help -

http://www.peachparts.com/shopforum/showthread.php?t=53955&referrerid=36147

http://www.benzworld.org/forums/w124-e-ce-d-td-class/1387161-electric-headrest-help-needed.html?referrerid=74064

Jeremy5848 · #10 02-05-2009, 12:10 PM

Also –

http://mbca.cartama.net/showthread.php?t=6339

Jeremy5848 · #11 02-05-2009, 02:40 PM

======================================
OK, got the back off and found nothing broken – the cable from the motor had come out of the gear mechanism.

Stuck it back in and the headrest works perfectly. Looks like only the springiness of the cable keeps it in place. I'll post pictures and details later today.
======================================

EDIT – Details and photos added

As was previously said, this is another one of those jobs that are easier once you've seen it done. Thanks to all who provided links and photos. Access is best with the seat moved and tilted forward as much as possible.

Taking the seat back off isn't bad at all. After removing the two Phillips screws at the bottom, I found that the slide down ("gently but firmly") technique did not work. Even the "whack it with a soft mallet" technique moved the back down only a little and I didn't want to use more force. I finally gave up on that and tried the "Phillips screwdriver #1 size" to pry the seat fabric out of the groove in the seatback. This worked well and I had both sides loose in a minute. Caution – don't lose the little metal clips (two on each side). They are supposed to stay on the seat fabric.

Once the seat fabric is pulled out of the grooves, the seatback then easily pulls down and off. BTW, this is a good time to repair/replace/tighten the netting if your seatback has that kind of pocket.

Once I could see the insides, the problem was obvious – would they all be this easy! For unknown reasons, the cable from the motor had come out of the mechanism (rack/pinion) and so wasn't doing anything. There was nothing broken – all I had to do was to plug the cable back into the mechanism and the headrest worked. First time in who knows how many years.

With the seatback in place, I found that pressing on the seat fabric with one hand made it easier to press the seat fabric back in the groove. Having someone sit in the seat and press back would be even better. A plastic pry tool works nicely to press the fabric all the way into the grooves. Again, be careful not to lose the little metal clips, two on each side. Put the two Phillips screws back in at the bottom and you're finished.