Now that it's mine... 1988 2.6E
 

Can someone ID a sound like that of an electric motor that would be triggered by locking the car from either front door when the car has been shut down? It also sometime happens when unlocking the doors. It is coming from the passengers side rear shelf/fuel filler door area. Is there a vacuum pump in that general location?

I am having a locking problem in that, when locking from the front doors, the rear doors sometimes lock, sometimes don't. Fuel door seems to be locked most of the time, even when rest of car is unlocked. Another point of interest perhaps is that the rear headrests will not function from the switch on the console. I'm guessing this is going to require some probing around the vacuum line and actuators in and around the suspicious area :eek:

Oh, I love these old Benz's but the vacuum systems can be testy :( Any suggestions where to start? (First, I should get out of bed :cool: )

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there's a vacuum pump under the rear seat, pass. side. good luck, chuck.

Why would the vacuum pump start up when simply turning the key in the door to unlock it?! :confused: :eek:

That vacuum pump unlocks the doors, it runs every time it needs to lock or unlock the doors

Interesting. I know that the pump did not behave in that manner on my '85 W123, hence my questioning on this car. I'm assuming my '95 W124 wagon door locks work off vacuum as well? If yes, I never hear a vacuum pump running after the engine is shut down like the subject car of this thread! Just like the soulful Marvin Gaye, I wanna know 'What's going on?'!

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On the wagon the vacuum pump is in a different place, its all the way in the back.


Your W123 used engine vacuum to operate the locks.