PeachParts Mercedes-Benz Forum - View Single Post - 1 leak fixed, now I need ACC vacuum servo help.

tcane · #10 12-30-2001, 12:45 PM

When I fixed my vacuum problems 5 years ago, the actuators cost $38 each from M-B. No telling how much now. After replacing the actuator I came across some info about a rebuild kit (diaphragm with the piston/rod and a sealing ring - as I recall - that cost 1/3 the price of the actuator), but I did not follow-up to see if the repair kit was actually available. A search for the kit would be worthwhile since you need to replace so many and good info for other members that need to fix their's.

As I recall, only the actuator for the main air door requires pulling the top portion of the dash on the 300D. Hopefully that actuator is still good. Also, a very slight leak or reduction in vacuum over a period of time for the actuators is allowable according to M-B.

The problem in removing the hard to reach actuators are the retaining clips. They can be hard to reach and remove/install without breaking the small plastic pin they fit onto. Best to remove the small bracket the actuator is mounted to if possible - as I recall, some of the bracket mounting screws were behind the actuator itself and could not be reached without first removing the actuator. Perhaps some other members have a favorite technique for removing the actuators.

When you buy the new actuators make sure the metal connecting rod moves freely without binding. A hard moving/biding connecting rod can cause the plastic piston/rod connected to the diaphragm to break or possible displace the diaphragm so it becomes unseated or tears. The new official M-B actuator I bought from the dealership had a very hard to move connecting rod caused by the connecting rivet being too tight (the same problem with the original actuator). I removed the connecting rivet and reinstalled it allowing for more freedom of movement.

You can by a dash cover for about $110-$125 that will look almost like the original. I do not know if the sponsors of this forum sell them, but check with them first. If they do not sell the dash cover, then check with Performance Products.

Good luck!
Tom