My door locks do not work and I decided to try and fix this problem but I have no idea where to start. I know some of you can point me in the right direction. They do not work at all. I had a 240D that would slowly push them up and down, but this one will not work at all. Thank you so much for your help!

1983 Mercedes 300D Turbo with 205K, Automatic

There are tons of threads on the forum. Do a search under 'vacuum' or 'door locks'.

Basically you have to trace vacuum in the lines from the engine bay, into the cabin (yellow lines in the floor) to all the door actuators (in each door).

The little MitiVac is invaluable
Golf tees work well to block certain passageways to divide and conqueor until you find the leaks

Good luck

diesel don

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DAILY DRIVERS:
'84 300DT 298k (Aubrey's)
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'84 300D 211k Mint (Arne- Undergoing Greasecar Conversion)

SOLD:
'82 240D 229k (Matt's - Converted-300DT w/ 4 speed

Start with pulling up the driver's side carpet. There you will see a channel with the yellow lines and rubber connections, like splitters, that route the vacuum elsewhere. Easiest way is to disconnect the outputs, and put some vacuum on them one at a time. You'll know which ones are leaking, because you will never build a vacuum.
Goes from the engine bay, through a yellow and white splitter, to two lines going into the cabin. One goes into the trunk, to the vac reservoir. The other one goes to the driver's door, where it gets split into red stripe (lock) and green stripe (unlock). From the driver's door, it goes to the spot right in front of the driver's seat that I was talking about.
I just did this last night, and had both a broken hard line on the lock side for the right rear door, and a failed rubber boot on the lock actuator on the unlock side of the passenger rear door.

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The lines hold up pretty good its usually the rubber T connectors or the actuators them selves.

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92 300D 2.5L OM602 OBK #59

Ditto here. If you have access to one, borrow a hand vacuum pump test kit. I borrowed my brother's, used it at various connections, testing how well the vacuum stayed in that part of the line. I started at one end and finally figured out that one of the rubber T connections was loose. I did a temporary fix and now the door locks on my 240 are quick as a wink.

Good luck
Nicolette

I bought a vac pump ( US general brand) from Harbor freight for about $18 bucks. But make sure you don't need it in a hurry or pay the extra shipping. You can solve your vac issues quickly with the pump. Without it, you'll have to run the engine and use the engines pump to keep a contstant vacuum. then pull lines and block them off systematically. All door locks I believe originate from the drivers door. Master valve. I've also heard that the actuators are common to leaking, so you might pull the door panel after you isolate leaky line, and plug that line before the actuator. If the other locks work. Hunt for a good used actuator on this site, or in a bone yard.
mike

I can only speak of the 92/93 300D. They DO NOT run off the engine vacuum system. Their is a seperate pump under the back seat on the passengers side. It's wrapped in foam. (I'm installing a remote lock fob system 3/6).

Is the pump working? Did you check the fuse?
You can unplug each yellow line and see if you can get a vacuum.

Attached is the wiring diagram

Attached Thumbnails

 

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92 300D 2.5L OM602 OBK #59

Bobo, he's got an 83, so none of this applies. Well, sorry, the yellow lines part does.
Ron, any updates?

D'oh... It was late.. I read 93... Sorry...

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92 300D 2.5L OM602 OBK #59