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Thread: Bmw 645 tapping noise with a difference

  1. #1
    Join Date
    Aug 2014
    Location
    england
    Posts
    15
    My Cars
    645ci 2004 convertible

    Bmw 645 tapping noise with a difference

    iv just done the top end hydraulic lifters,, near side and of side, lifters, checked intermediate fingers ,checked cams , all this was done as the car had a loud single tapping,
    put car back together a all sounds good on all cylinders, but very mechanical sounding tapping is still there, i noticed yesterday if i remove the oil cap slightly the noise goes completely, but obviously the engine runs lumpy, due to lack of vacuum ie oil cap off, anyone any idea ??

    doing my nut in

  2. #2
    Join Date
    Feb 2015
    Location
    Athens, AL USA
    Posts
    9
    My Cars
    E60, E46
    I pulled valve cover on my 650i and found nothing...but have been reading about injectors being the source of this tapping...have you had success finding the problem?

  3. #3
    Join Date
    Feb 2010
    Location
    Hampshire UK
    Posts
    8,867
    My Cars
    99 840ci Sport Indv
    It is usually the vacuum pump - try removing the vacuum line that runs to it and see if the noise changes (it won't go away completely as it only removes a small amount of vacuum) That is why the noise goes away when the oil cap is removed as it relieves the load on the pump.
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  4. #4
    Join Date
    Feb 2015
    Location
    Athens, AL USA
    Posts
    9
    My Cars
    E60, E46
    Hi...can you explain how a break vacuum pump has anything to do with the lifters and a noise coming from rear drivers side of the engine? I did replace lifter, seals and have stopped smoking...runs good...just this load knocking noise from drivers side head near the firewall....I just don't see how a mechanical pump on the front of the engine has anything to do with it....thanks for helping me understand...

  5. #5
    Join Date
    Feb 2010
    Location
    Hampshire UK
    Posts
    8,867
    My Cars
    99 840ci Sport Indv
    Lifting the oil cap removes the load from the vacuum pump - and so it stops knocking. The pump is driven by one camshaft and the noise can be transmitted along it. But, the proof is in the pudding as we say - if removing the vacuum line makes a difference then the pump is the main suspect.

    It sounds implausible, but I came across this when working on my pump:

    http://www.meeknet.co.uk/E64/Timms_B...eak_Repair.htm
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


    My BMW Repair YouTube Channel
    My Current 840ci Sport Individual
    My Current 650ci Sport Individual
    My E31 Repair and Information Website
    My E38 Repair and Information Website
    My E63/E64 Repair and Information Website

    Chase - Heroes to a generation

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