switching a w116 to w126 lock system?
 

Since I have a good 1988 560SEL parts car that I have been selling items out of and also putting some in my 1979 300SD, I was wondering if anyone has ever hooked up newer vacuum pump to the lock system in an older car like mine that doesn't have one? I have a good working electric vacuum pump and it looks like it would be simple to just hook up the door to and fro lines to the pump and wire it up. I'm just wondering if there would be something more to it or would it be just that simple??

You also need at least 1 of the lock mechanisms and associated wiring if you do convert. The motor is triggered by the vacuum lock mechanism in the door that's unlocked with the key. The W126 has mechanisms in both front doors and the trunk.

IIRC W116 pods have a chamber to lock with vacuum and a chamber to unlock with vacuum. W126 pods have a single chamber that locks with vacuum and unlocks with pressure.

I’m still thinking how to wire the pump to run in vacuum mode when you lock and unlock. It might be easier to fit two pumps.

Sixto
98 E320s sedan and wagon
02 C320 wagon

That's true. My 300SD has two hoses to each lock to lock and unlock. The 560SEL has a single hose. I'll just keep my current system since it does work. I figured if it was an easy swap why not, but not looking to do a conversion for no reason.