Hello

Have used this resource a lot to keep my 90 300CE-24 COUPE running well but have not yet posted. I have an issue that I cannot find in the achieves and would appreciate any suggestions.

Passenger front seat (RHD) will not lock in position when it should. Drivers side locks when engine on doors closed etc. I have checked the vacuum lines under the rear rest squab there is plenty of vacuum. The head rests deploy as they should (also vacuum controlled) and as I say the drivers side is fine.

I removed the hoses to the seats at the take off under the rear seat and applied a vacuum using my mity vac. On the drivers side I could see the locking mechanism moving as I applied vacuum. Once I got to about 85psi the mechanism moved no further. It moved far enough to lock the seat back in place. The vacuum held steady at 85psi.

When I tried it on the passenger seat the locking mechanism moved only slightly. Not enough to lock the seat back. The vacuum also held steady at 85 psi.

The fact that the vacuum held steady at 85psi seems to suggest that the diaphragms are not leaking. The problem therefore seems to be mechanical. Something is causing the vacuum to not pull the mechanism sufficiently to engage with the locking bar? the locking bar is rotated on a shaft by a cable that is obviously pulled by the diaphragm when under vacuum. There does not appear to be anything impeding the rotation of the locking mechanism and the cable looks clean and seems to pull smoothly for the short distance it is actually moving.

Any ideas?

Chris in sunny Sydney Australia.

 

Can you move the mechanism by hand and engage the lock? My first thought would be something jamming up the works. I another vehicle I found trail mix jamming the seat mechanism. We don't talk about who was eating trail mix in the back seat and dropped most of it. The fix involved a lot of work as the seat needed to be moved before the bolts could be reached and the seat would not move due to being jammed.

Sorry, back on topic. First determing if the latch is jammed or if the cable is not pulling far enough.

 

Yummm was it a good brand of trailmix ??? Any left ? LOL
I am too scared to look in back seat of my wife's car.
Something is there, not of this planet, surviving on dropped scraps by the kids !

 

[QUOTE=keith0alan;5473798]Can you move the mechanism by hand and engage the lock? My first thought would be something jamming up the works. I another vehicle I found trail mix jamming the seat mechanism. We don't talk about who was eating trail mix in the back seat and dropped most of it. The fix involved a lot of work as the seat needed to be moved before the bolts could be reached and the seat would not move due to being jammed.

Yes I can move the mechanism by hand. It appears that the cable from the diaphragm is not pulling the lever sufficiently. I am wondering perhaps cable binding on the outer housing or requires adjustment. Can't believe it is the latter as hard to see how something like this could go out if adjustment.

Suspect I have to remove the seat and check operation of the cable. If the diaphragm holds a vacuum then I don't see how there could be any problem there.....

 

Could be the cable is streched or the actuator has lost some travel. How much does the cable move vs how much it needs to move? If you are almost there it might just take a little shimming.

 

I have the same problem. Front seats won't lock.

 

I had a problem with my passenger seat-back not locking on my E320 coupe whilst everything else vacuum related was ok. I had to buy a new underseat vacuum unit (A 124 800 08 75) because a tiny piece of plastic had broken off which secured the locking cable to the diaphragm.


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