98 E300 vacuum question
 

I have the vacuum operated seat lumbar adjuster. It never worked since I bought the car. I started looking at it today. The EPC parts list shows a vacuum pump. It looks like it might be under the rear seat. Does any one know where the pump is located ? Also is it supose to lift the rear head rests ? I can put them down with the button on the dash but if they are suppose to go up by themselves they don't. They come down hard and fast. Is that normal ? I think if the pump was bad I might have other problems.

1/2 an answer.....Head rests must be manually raised. Dash switch *only* lowers them.

I'm not sure the '98 is the same as my 124, but if so the pump is a vacuum/pressure pump, and also operates the central locking system, is under the rear seat cushion.

In my '99, the driver's headrest rises when the seat is moved back. It "thinks" somebody taller is going to drive. It's motor-driven, not vacuum.
Steve

Yes it is under the rear passenger seat adjacent to the battery. I would bet it is the controller on the seat that has a leak, or the "bag" in the seat is leaking too. This is a small compressor otherwise you would have negative lumbar adjustment with vacuum.