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w124 om606 air in fuel lines

Discussion in 'Engine' started by jjrodger, Aug 21, 2012.

  1. jjrodger

    jjrodger Hardcore MB Enthusiast

    Messages:
    121
    Joined:
    Apr 7, 2004
    As the title suggests, there is air in the fuel lines of my om606-equipped w124 (E300 Diesel T-Model, 124.191). I have researched this as much as I can and just need a few pointers. I can see bubbles in all of the clear plastic tubes, including the tube that leads from the fuel heat exchanger to the fuel pre-filter. Am I right in concluding that the air leak must be upstream of the fuel pre-filter? If so, am I right in concluding that the air leak must be either at the fuel heat exchanger or at the tank strainer or at some pipe join in between? There is no diesel on my driveway. Surely if the leak anywhere else, I would not be seeing air bubbles in the clear pipe which goes from the fuel heat exchanger to the fuel pre-filter? The bubbles appear to be travelling with the fuel (obviously, I suppose). Thanks for your help.
     
  2. SilverSaloon

    SilverSaloon Hardcore MB Enthusiast

    Messages:
    7,758
    Joined:
    Mar 16, 2004
    Car:
    1994 W124 E300D Estate, 1985 R107 280SL
    yes there will be one or more leaks before the heat exchanger.

    A few things to note from my own experience of these:

    - main black rubber fuel pipe in engine bay going to HE can go brittle at the ends. worth replacing

    - main black rubber fuel pipe at tank end (from tank to metal pipe that runs under car) also worth replacing for same reason.

    - in-tank strainer blocked. If this is blocked basically the car finds it easier to suck air than fuel hence bubbles. The tank strainer can be removed and cleaned (its just mesh)

    - the HE can also leak air if its not torqued down to the head properly. There is a large green rubber gasket inside. i removed mine, cleaned it up, smeared some silicon sealant on it and refitted. Nice and tight now.

    Of course, also replace all those clear pipe orings:

    MERCEDES E300,E250,C250 VITON FUEL O-RING KIT SVO,WVO,BIO-DIESEL,210,124,202,C,E | eBay
     
  3. OP
    OP
    jjrodger

    jjrodger Hardcore MB Enthusiast

    Messages:
    121
    Joined:
    Apr 7, 2004
    Thanks you for this. The 'O' rings and clear plastic pipes have all been done recently. It sounds like it is upstream I need to concentrate on, the tank strainer, the pipe to the heat exchanger and the heat exchanger itself. Thanks again.
     
  4. SilverSaloon

    SilverSaloon Hardcore MB Enthusiast

    Messages:
    7,758
    Joined:
    Mar 16, 2004
    Car:
    1994 W124 E300D Estate, 1985 R107 280SL

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