My '72 w108 vacuum locks appear to be working.

Sometimes I leave home with the doors unlocked and arrive at my destination with the doors locked. I cannot close the driver or front-passenger door when they are open, and after I installed the fuel door (my car didn't come with one--I found one online), it locked.

I just don't know if they are not working right or I don't know how they work.

• Are all locks supposed to pop-up when I open the driver's door?
• Are they all supposed to close when I lock the driver's door?
• Is there a trick to locking/unlocking the fuel door?

Any help sorting this out would be greatly appreciated.


Thanks!


Jose

__________________
Current
1972 280SE 4.5 Dark Green, Cognac. Pics!
2014 Range Rover Sport Supercharged. Santorini Black, Dynamic Package, Front Climate Comfort and Visibility Package, Vision and Convenience Package.

Gone But Not Forgotten
2010 Explorer Limited, 2010 R350 4MATIC, 2011 Jeep Grand Cherokee Overland, 2009 Audi A4 Cabriolet, 2009 Ford Flex, 2008 Mercedes-Benz ML350, 2008 Mercedes-Benz E350, 2007 Mercedes-Benz C230, 2005 BMW X5.

[*]Are all locks supposed to pop-up when I open the driver's door?
Yes!
[*]Are they all supposed to close when I lock the driver's door?
Yes!
[*]Is there a trick to locking/unlocking the fuel door?
Locking the driver's door locks everything, including the fuel door; unlocking the driver's door unlocks everything, including the fuel door. Unlike all the other locks in the system, the fuel door ONLY gets vacuum during lock, and the fuel door lock has a spring in it; when there is no vacuum it's unlocked. Pretty sure that was an intentional failsafe.


I posted the diagram from the parts manual in one of the threads. I am unsure if there's a more detailed diagram anywhere. "Back in the day" I'd bump the driver's lock down while driving and all the doors would lock. I'd also open the LR door to lock the car by pushing the button down, vs using the key. The Germans designed it so you can't push the button on the driver's door down when it's opened, so you can't lock your key in the car without using it (or locking from behind).

__________________
Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

Hi Tomguy,

Thanks for the reply and detailed info. Mine are definitely not working right then as locking/unlocking the driver's door has no effect on the rest of the locks.

I just bought the car, so I'll add it to the to-do list. For now, I'm gonna keep the fuel door vacuum line disconnected. I had a close call a few days ago when it wouldn't unlock.

__________________
Current
1972 280SE 4.5 Dark Green, Cognac. Pics!
2014 Range Rover Sport Supercharged. Santorini Black, Dynamic Package, Front Climate Comfort and Visibility Package, Vision and Convenience Package.

Gone But Not Forgotten
2010 Explorer Limited, 2010 R350 4MATIC, 2011 Jeep Grand Cherokee Overland, 2009 Audi A4 Cabriolet, 2009 Ford Flex, 2008 Mercedes-Benz ML350, 2008 Mercedes-Benz E350, 2007 Mercedes-Benz C230, 2005 BMW X5.

If you find one of the servos is not working then don't replace the entire thing. The main cause for servo failure is a cracked rubber disc and while it is somewhat time consuming it is very simple and cheap to replace the discs.

The entire plastic body of the servo is far more expensive than the discs, but if you do need the plastic body then pick one up off of Ebay as someone always seems to have one for sale.

Seems like I paid about $20-25 each for two servos three or four years ago. They were new.