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Sounds like a slight rod knock

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    #16
    Any more news? lol Don't mean to be a bother, but this mystery with my own car is really getting to me now.

    One shop quoted me pretty high and wants to look at my clutch and trans when I'm CERTAIN the noise is coming from down low but towards the front/center of the engine bay.
    [Mine is an S52 from a M roadster (Z3]

    Further verified that nothing affects the noise aside from acceleration. Nothing changes when clutch in/out or in gear. Only goes away when hammering down on the power.

    Getting a bit more persistent as well, topping off or changing oil viscosity doesn't seem to subside it much like it did.

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      #17
      Originally posted by CptPhilmeister View Post
      Any more news? lol Don't mean to be a bother, but this mystery with my own car is really getting to me now.

      One shop quoted me pretty high and wants to look at my clutch and trans when I'm CERTAIN the noise is coming from down low but towards the front/center of the engine bay.
      [Mine is an S52 from a M roadster (Z3]

      Further verified that nothing affects the noise aside from acceleration. Nothing changes when clutch in/out or in gear. Only goes away when hammering down on the power.

      Getting a bit more persistent as well, topping off or changing oil viscosity doesn't seem to subside it much like it did.
      The engine was take apart by the machine shop and found no visual wear.. Every single piece was checked, nothing found. They put the short block back together and all tolerance are within spec just as I had checked it..I'm trying a different head and a new southbend clutch, pressure and another flywheel and see if the noise is still there. I just mated the engine and transmission together last night. It should be going back into the car by the weekend.. I'll keep you updated.
      88 e30/s50 gt35r turbo m3



      96 gt4094r turbo m3
      452 rwhp, 455 rwtq at 14 psi 91 octane
      681 rwhp, 684 rwtq at 25 psi E65

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        #18
        Update, I finally put the engine back in, and that knock sound is gone..The changes I did, was put a new clutch, pressure plate, flywheel, and another head. The reason I replaced the head, was because the head I had initially installed had the non-tapered valve springs while using the s50 cam trays which use the lifters made for the tapered springs..So since I had another head ready, I went ahead put another head.. So in the end, I don't know what was causing that rod knock sounding noise..
        88 e30/s50 gt35r turbo m3



        96 gt4094r turbo m3
        452 rwhp, 455 rwtq at 14 psi 91 octane
        681 rwhp, 684 rwtq at 25 psi E65

        Comment


          #19
          What viscosity oil were you running?

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            #20
            Originally posted by NotJesus View Post
            What viscosity oil were you running?
            the first time around, I tried different thickness and at the end I went thicker to 20/50'' but the sound was there no matter thickness I used..
            88 e30/s50 gt35r turbo m3



            96 gt4094r turbo m3
            452 rwhp, 455 rwtq at 14 psi 91 octane
            681 rwhp, 684 rwtq at 25 psi E65

            Comment


              #21
              Thanks for keeping us updated!

              Seems at least one stop had a pretty good idea of where to look. Will definitely investigate the clutch first, if it's still heard I'll make the call to do a full engine sweep.

              ::Beers::
              Last edited by CptPhilmeister; 11-05-2018, 04:29 PM.

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                #22
                Fixed!

                Turned out to be definite Rod Knock, thankfully fixed by a new set of Rod Bearings. Back to smooth running for now!

                :mrgreen:

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