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black fuel filter

tdi-man Apr 6, 2011

  1. tdi-man

    tdi-man Well-Known Member

    is it ok for the fuel filter to be black after say 12 months ?

    i have been told that it should not go black as this is a sign that the injector seals are worn ?

    i am asking this as i have had mine replaced over 18 months ago and am wondering if the job was done rite ?

    also cant remember if they used new stretch bolts on the injectors ?

    i did buy 03G198051A X 4 can any body tell me whats in this part number please ?
  2. Lewis583

    Lewis583 Active Member VCDS Map User

    ETKA shows that part number as "Set of seals for unit injector"
  3. tdi-man

    tdi-man Well-Known Member

    ok no stretch bolt
  4. Khufu

    Khufu Well-Known Member

    I have to clean the diesel filters on our petrol station pumps often. The added bio-diesel grows into a black mold on them and blocks them (makes pump run very slow) A total pain in the butt!!!
  5. a8 tech back

    a8 tech back Member

    Black is fine and its a characteristic of pump duse blow pass where combustion gases return in the fuel lines
    As mentioned in your other thread take a sample poor into a glass and leave it for 24 hours
    You should see separation, if excess soot is found then it will indicate worn injector seats or seal or even pitting of the cylinder head injector seats
    If oil is found that's ok as oil is a fuel and should have no impact on combustion as long as its not excessive but you find everyone fits tandem pumps for no other reason that they assume no oil should be present but if 1 year on they look again the fuel will again have oil content as its normal for this type of engine and unavoidable however it appears unsightly so we assume there is a fault
    If you wish you can flush the fuel system to remove the accumulated build up
    Soot is the killer and indicates excess blow pass but again there will always be a small % of soot present
    I would replace the fuel filter more frequently and use a higher grade of diesel if cost affective

    As for the injector bolts they must be replaced every time with a low torque setting of 4 nm if I recall and correct install of the injectors is a must
    Last edited: Apr 7, 2011
    Pav likes this.

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