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1999 ML320
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350 Posts
Discussion Starter #1
So the drivers side seat base (where your bum goes) is only tilting on the outside. The center side seems to jam. Does this unit have two motors? Could one be dead? I haven't ripped it apart, just peered nervously underneath.
 

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Premium Member
About a dozen 1988, 1989, 1990, and 1991 sedans, wagons, 4Matics and 1 coupe
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5,454 Posts
Just one motor for each function. A cable exits both ends of the motor to power each side mechanism. Check for coins, paper clips, etc. that get dropped and jam the mechanism.
If more than a cable is broken I'd find a used seat in a salvage yard ans swap out your regulator. You *can* work on the regulator but it's not easy or fun. A lot less offort to swap the whole regulator...
 

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Registered
1983 240d - 1985 300d - 1984 280sel
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393 Posts
I have this same problem, and from doing a few searches, it seems like it is not an uncommon problem. Someone did a write up on repairing it on the forum somewhere.
 

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1999 ML320
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350 Posts
Discussion Starter #4
Thanks guys, I'll try to yank the seat out in the upcoming week and have a look. That is, if there is no coinage in the mechanism that I can find.

Cheers.
 

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Registered
1988 300TE 280,000 Miles
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198 Posts
I'm going to jump onto this thread because I have the problem described in the title. My issue is not the Switch though.

I have the seat apart. I can put 12v to the seat and one side will raise and lower, this is the drivers seat, and the inside rear will not raise up and down.

I can feel the drive on that actuator vibrating, so I pulled the cover off. The square drive cable is turning, but the worm gear is not. Here's a PIC:

PIC

It almost looks like the cable isn't engaged maybe? I can't see if it goes in the worm or not.

Any suggestions about what to look at next?

EDIT: OK, pulled off the motor end of the cable and was able to advance the cable into the worm and it works. The cable is in perfect condition. What would allow the cable to back out of the worm just enough to not work?
 

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Registered
1988 300TE 280,000 Miles
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198 Posts
Looks like I fixed my issue.

After taking loose the cable on the motor end and seeing that a drill would drive the actuator. I examined the cable and it was perfect. So it seems that my cable was not engaged enough in the worm drive. I put it all back together making sure everything was tight and no more problems. Strange!
 

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1999 ML320
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350 Posts
Discussion Starter #7
I fixed mine as well. It had exactly the same issue. Only, the cable worked its way loose after a couple of days, so I put some JB Weld on the end and insert it into the worm gear again. It hasn't come loose yet and it has been in there a couple of weeks. Time will tell if it will hold.
 

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1988 300TE 280,000 Miles
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198 Posts
I fixed mine as well. It had exactly the same issue. Only, the cable worked its way loose after a couple of days, so I put some JB Weld on the end and insert it into the worm gear again. It hasn't come loose yet and it has been in there a couple of weeks. Time will tell if it will hold.
Yeah, I'm worrying mine will be back.

Did you just "build up" the end with JB weld?
 

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1999 ML320
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350 Posts
Discussion Starter #9
The cable is a wire wound type that is pressed square to fit into a square receptacle. I just cleaned out the worm gear receptacle and degreased the cable end and then smeared JB weld on the end. I guess I figured the wires would provide enough friction for the epoxy to get a grip

I had practiced putting the cable in a few times so I knew how far in could go without pulling it out from the motor end. I then inserted the cable and carefully put it all back together.
 

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1983 240d - 1985 300d - 1984 280sel
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393 Posts
Did you guys have to remove the seat to do the fix?
 

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1999 ML320
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350 Posts
Discussion Starter #12
Actually I didn't. You just move the seat all the way forward revealing the gear housing on the seat rail. Pull the plastic cover off, open the gear housing and you are there. I guess it would have been a bunch easier if I had removed the seat. I am not a big person so maybe that is in my favor.
 

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1988 300TE 280,000 Miles
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198 Posts
Actually I didn't. You just move the seat all the way forward revealing the gear housing on the seat rail. Pull the plastic cover off, open the gear housing and you are there. I guess it would have been a bunch easier if I had removed the seat. I am not a big person so maybe that is in my favor.
Heh! For some reason, everyone of your posts are a mystery to me.

I don't know what you did with the JB weld. I read and re-read to no avail.

There was nothing I could just pull a cover off to access mine. The one end of the cable is held in with a Circlip, and the other end where I think you are talking about appears to be held tight with two bolts. Additionally, since my seat won't elevate, working area is not much under there. You did this in the car? I'm seriously impressed!

I'm sure some folks would Love it if you can post some pix with annotations if you have them.
 

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1999 ML320
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350 Posts
Discussion Starter #14
Sorry if there is confusion. I took a couple of quick photos. I'm not going to open it up again so sorry about that. Basically you remove the 4 bolts, one of which holds the cable retainer bracket. Open the aluminum faceplate to access the worm gear. Remove the worm gear and the cable as it will be in the worm gear. If you give the cable a tug you will notice some play. Pull it out too far and it will come out of the motor end. You have to find where the cable will be both in the motor and in the worm gear. Clean the cable end and worm gear with some brake cleaner and add your JB. I just scooped some of the excess grease that was on the big gear to re-lube it before I put it all together.

This is really just a hack repair. If you pull the seat maybe you can find out why it is slipping out of the motor. There might be a more professional repair. All I know is that mine works now.
 

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1983 240d - 1985 300d - 1984 280sel
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393 Posts
Cool. Thank you! Hopefully it will be the same on my '93.
 

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1988 300TE 280,000 Miles
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198 Posts
I must be really dense cause I just don't understand what the JB weld is doing? Here's my PIC I posted before inline. (Glad the Forum here resizes and Thumbnails!)

 

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1999 ML320
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350 Posts
Discussion Starter #17
From what I remember it seemed to me that there were enough irregularities inside the worm gear for the JB to get a grip and keep the cable from working its way out again. The load is primarily torsion not pull so you don't need much to keep that cable in place.

If I recall there was a thread some time ago where someone used JB weld because the inside of the worm gear had rounded. It worked for him so I thought, what the h*ll I'll give it a try. Might have been at Peachparts that I read that.
 
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