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Discussion Starter #1
This is strange. My 78 300cd is in super shape. runs like a top. does the 1/4 mile in under a minute. :) its a nice example of a 123 coupe except for the strange and silly black painted bundts.
after the car is parked for a while, when I open the driver's side door, I hear a clattering sound, as though something is flopping around. at first I thought it was coming from inside the door ( I thought the door check maybe?) but it seems like it might be coming from under one of the front seats. could it be something that has to do with the flip-forward seats? I noticed that my passenger seat sometimes needs some coaxing to get it to release. is this a vacuum system?

another vacuum long shot: it it is, might that be why my cruise control works only partially ( Accellerates but wont hold speed)

fortunately, all the locks work if that helps...

thanks all-
 

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When you open the door, a system triggered by the door jamb switch vents vacuum to two diaphragms on each seat. The diaphragms actuate a hook-looking lever to lock the seats while the doors are closed. You can see the lever and pin if you look on each side of the seat near the pivot point for the back rest. The button on the side of the back rest allows the seat to be unlocked manually when the doors are closed. I suspect the noise is somehow coming from these. Maybe the levers are binding and need cleaning and lubing.

Your cruise control problems sounds common. It is usually a problem with the cruise control amplifier (brain box) under the dash. About the only fix is to have it repaired. Have heard of some people resoldering connections to get it to work, but if you do that, the people who repair them probably won't touch them after they've been tampered with.
 

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Discussion Starter #4
that's indeed it! I messed around with the car again today- the problem is under the driver's seat. when either the door is opened or the button is pressed, I get this little "twoingly twoinga" noise..

is that mechanism under the seat, or maybe inside the back?

thanks,

-M
 
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