Simple Plug for Supercharger Vacuum Port

A very common place for a vacuum leak on the E55’s is that port on the rear of the supercharger with a strange multi-piece plug in it.   I assume that port is used for the brake booster on cars that don’t have the SBC system, but it is beyond me why the engineers at Mercedes-Benz decided to make a three-part plug to fill it instead of using a simple rubber plug.  This is especially strange since there is an existing Mercedes part that seems to work perfectly.

I was at Mercedes Benz of Portland today, trying to get a new plug for my car since the old one is leaking.  For some reason the parts diagram on the computer only shows two of the pieces required.  It was clear that it would not work without that third piece, so after some head-scratching the parts guy said “Hey, I’ve got an idea!”  He ran into the back and two minutes later came out with a plug for the windshield washer on a CLK320 (part number 210-987-00-45) that is the perfect size for the port in the supercharger!

7 thoughts on “Simple Plug for Supercharger Vacuum Port

  1. Hi,
    I know this is an old post but trying to see if anyone can provide some insight. I’m trying to replace the plug with the rubber grommet but am unable to remove any part of the plug.
    Do I have to press the tabs on the side of the black part to pull out the plug itself ?
    How about the black part itself, is there a method to taking it off or do i just force it off ?

    Thank you

    1. The whole thing is held in with metal tabs that point backwards and dig into the aluminum. They are a pain to get out but you just have to pry them out. Will probably break during the process.

      1. Thanks for the reply. I will try breaking it off, hopefully I can do so with the supercharger installed. A few questions though.

        1) are there any parts that can break off and fall inside the supercharger ?

        2) the nipple part of this weird plug, does it slide out in anyway or will that have to be broken as well ?

        Thank you again

      2. Another different issue I have, if you have any insight into. Car is a 03 e55 with m113k.
        Bank 1 runs leaner %age wise of bank 2 for LTFT. Smoke tested several times, no leaks. New spark plugs, coils, wires, sensors, 02s etc.
        The weirdest part is that bank 1 will continue to go lean up until 9.1 – 9.4% then will start dropping down and stop around 4.7% after which the cycle of going up and down repeats. During this time bank 2 goes up and down between -0.6 and +3.1, which is its highest I’ve ever seen.
        Also the car seems to reset LTFT if not started within 5 days, battery & alternator are good, no draw from battery when parked and it does if it’s connected to a trickle charger or not.

  2. Hello Joe. I’ve tried to replace this overengineered thing with the simple rubber plug like you did. But I failed at removing black plastic sleeve which seems somehow locked into supercharger’s body. I removed all internal things up to a small oring but the sleeve stays and won’t go out. It only rotates a little. Is there some trick involved with removing it? Supercharger is on the car. Car is W211 E55.
    BTW. Nice site you got here 😀

    1. That piece is held in by a ring of little metal tabs that dig into the aluminum. You just have to pry it out, which may be quite difficult with it still on the car. I did mine on the workbench.

      1. Thanks for quick answer. Yes, on the car the space to “operate” is restricted. I will try anyway.

Leave a Reply