123 Vacuum leaks

[Ian Waterhouse]

Can anyone please help?  I am lucky enough to have 2, 230 123's both of which loose their vacuum reserve.  

One within 20 mins, the other overnight. I have replaced the plastic ditribution units on the engin side of the bulkhead, which helped a bit.  But there is obviously a leak somewhere.  Can anyone please point me in the right direction?  

 

[Andy]

Hi Ian,

To carry out accurate diagnossis of the central locking system. You need to be able to create a vacum in the system using a little tool called a "mity vac". Otherwise its  a bit of a slog. Usually its one of the door cells playing up. But it could be either the petrol flap cell or boot cell.

You will find the connections to start from on the osf. Remove the carpet. Under the plastic side cover,near the inner sill you will see the plastic pipe connections where they all meet. There is another one on the ns. There is a line from the osf to the nsf. Supplying vacuum to the ns of the vehicle. There are two lines red & green. One is to open the other to close. You need to test both sides as they work independantly. So that the reason you could close the vehicle. Then not all the doors will open. Study the lines and you will see that they all go to a door or boot or petrol flap. With out a mity vac its trial and error. You could just try disconnecting them one by one and blanking them off. To find which one is the problem.

Hope I have been some help.

Regards

Andy @ www.mercedesservicing.com

 

[wportre]

I have just mended mine (as Andy hinted, it was a door slave - the rubber seal on the "output" piston had split). I had listened for hisses for weeks and was getting frustrated. Then I had my son BLOW into the control lines in the driver's door. These are key: by sucking green (unlock) or red, you can start to isolate the leak - your mouth can easily tell. "My" seal is on the unlock side, since the seal is on top of the unit. But the blowing was a lot noisier than the vacuum leaking and that's how I found it. Plus you can mess around with bubbles etc that way.

Good luck: I'll bet you a pint it's that seal.

 

[Andi Beckett]

I 've had trouble with this in the past and it turned out to be a perished rubber seal on one of the rear door slaves.
It cost about £12 to rectify, plus lots off fiddling about with the door lining!