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rod knock, vanos, or normal ?

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    rod knock, vanos, or normal ?

    hey guys,
    i purchased this 2006 m3 vert 6mt with 111k miles a couple of weeks ago, the car drives great but i just noticed this noise. can you guys please help me diagnose this?

    no codes, rod bearings not done but i have an appointment next week







    noise seems to goa way when revs are raised, or at lease not as noticeable


    Last edited by Moi; 08-01-2023, 10:54 AM.

    #2
    Edit: post links fixed
    Last edited by nahvkolaj; 08-01-2023, 08:28 AM.

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      #3
      Originally posted by nahvkolaj View Post
      Not sure if it’s because I’m on mobile but none of the videos/links work in browser or Tapatalk app.
      fixed, thanks for letting me know

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        #4
        Sounds like a rod knock to me, but I've only experienced it on a dirt bike engine. Wait for some other to chime in

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          #5
          This does not sound good. If I were you I would stop driving the car and tow it to the shop.

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            #6
            The water pump had already done on your car ? The valve clearance is ok ?

            This noise is not normal for this engine and it's not really easy to define by video. Hope your mechanic fo=inds it and fixes it 😉

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              #7
              pull the valve cover and inspect all rockers, shim clearance and timing chain guides. There's a bolt behind the driver side chain guide, verify it's not damaged or sheared off.

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                #8
                Definitely do some more investigation before running the motor. It could be as simple as a loose spark plug, but better safe than sorry on noises that track to engine revolutions like that.

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                  #9
                  Originally posted by M3schnitzer View Post
                  The water pump had already done on your car ? The valve clearance is ok ?

                  This noise is not normal for this engine and it's not really easy to define by video. Hope your mechanic fo=inds it and fixes it 😉
                  i do not believe it was done.
                  im just going to have it towed to the shop and have them put an ear on it.

                  thank you

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                    #10
                    That sounds like rod knock to me. Don't even start the engine. At idle, the culprit is still getting smacked against the rod a few hundred times a minute. Basically like smacking the inside of your rod and your crank with a hammer, no to mention causing it to be out of round. I would check roundness and the clearance because there may be damage. That noise means $$$ regardless of what the diagnosis will be.
                    This is my Unbuild Journal and why we need an oil thread
                    https://nam3forum.com/forums/forum/m...nbuild-journal

                    "Do it right once or do it twice"

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                      #11
                      Sounds like rod knock, but as others have said, it's very difficult to diagnose abnormal engine sounds via video.

                      Remove the oil filter housing lid and inspect for glitter. FYI if it's spun a bearing, there will be glitter in the oil. If this is the case, you can not just replace the bearings and call it a day; the corresponding crank journal will be scored and require machining at the very least.

                      Otherwise, remove the valve cover and inspect the valvetrain for any signs of damage

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                        #12
                        Ooof. I would not drive it or start it again. Call the shop who is scheduled to do your rod bearings and tell them what's going on so they can be prepared to have the car probably longer than one afternoon!
                        http://www.natehasslerphoto.com
                        '99 M3, Hellrot/Sand Beige, slicktop
                        '01 M3, Imola/black

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                          #13
                          Originally posted by Moi View Post
                          noise seems to goa way when revs are raised, or at lease not as noticeable​
                          The same noise followed the rpm -- sounds like rod knock.

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                            #14
                            It does sound like rod knock but I’m not quite 100% convinced as it goes away with increasing revs?. It’s unlikely to be good results either way I’d tow it to a shop that can hear it in person and properly diagnose

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                              #15
                              Originally posted by digger View Post
                              It does sound like rod knock but I'm not quite 100% convinced as it goes away with increasing revs?. It's unlikely to be good results either way I'd tow it to a shop that can hear it in person and properly diagnose
                              Agree someone experienced ought to take a look at it, but I want to speculate a bit. Could it be that as oil pressure increases it gets more oil to the bearing and lessens the knock?

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