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M42 Engine Noise around 3000rpm

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    M42 Engine Noise around 3000rpm

    ok I used the search function and since noises are subjective im not sure if my noise is addressed.

    M42 gets this metallic buzzing sound right around 3000 rpms. usually anywhere from 2900-3500 is when its most noticeable and it seems like maybe its getting worse

    some facts:
    -chain tensioner replaced
    -timing chain/sprockets looked almost new when i did the valve cover gasket
    -no plastic pieces in oil
    -noise happens under load, stationary, in gear and out of gear
    -its not the heat shield
    -maybe unrelated deceleration whine
    -theres a consistent small oil leak somewhere on the passenger side that has everything covered in oil, it drips oil but not enough to need oil often

    potential causes ive thought of:
    -motor mounts
    -water pump
    -timing chain/case related (in which case ill be pissed)
    -exhaust manifold leak

    potentially unrelated but today for the first time i saw the temp gauge start to rise above the half way point after idling for a few minutes at the atm but maybe im being paranoid. i feel like the noise is getting worse but im no m42 expert and i just dont want this thing to take a shit, but by the time i do the remaining "for good measure maintenance" with everything in the timing case ill be enough into it to justify an engine swap

    #2
    Are you able to take a video and pinpoint noise location?

    Have you tried using the long screw driver trick to listen for the noise, assuming it's coming from the engine itself, and not an ancillary mechanism?

    Water pump bearing can be going, but you would need to rev the motor up to the 3k rpm to really verify.


    Oil leak from the passenger side? Any chance it can be from the head/exhaust stud that plugs into the oil galley?

    What about lower oil pan leak? You mentioned timing covers, but did you replace the gasket?

    When has your oil filter housing gasket last been done?


    I'm so intimate with these m42 engines as of late. I'd dive right in and bathe in it's oils until the issue was fixed.


    GL
    world renown Harry Potter expert
    sigpic

    Comment


      #3
      You say its not the heat shield, but which ones have you looked at. Exhaust manifold heat shield, where it bolts to the head was one of mine. Along with the heat shield over the motor mount, same side. And the the heat shields at the cat. They all may have small cracks the buzz.

      Sent from my SM-G900P using Tapatalk

      Comment


        #4
        I had something similar years ago and it was, ultimately, the death of the engine.

        Two things to check:
        1) The upper bolt in the driver's side timing chain guide rail. It's the one that secures the threaded collar part to the cylinder head. Sometimes the threads in the head strip out and the bolt head rattles against the upper timing case cover. This needs to be fixed because the bolt will wear through the cover, as well as allowing lots of slop in the chain. The top bolt should be M6x45mm if the newer style plastic guide is installed, but a lot of times, the 40mm bolt from the old guide design gets reused and strips the head.

        2) This one is a bitch because you have to completely open up the timing case, and I do not know if you can even visually see the issue. Anyway, this is what happened to me. I had the buzzing at 3000RPM for about a year. It was coming from the front of the engine, I replaced all sorts of timing chain related stuff, and nothing helped. It ended up being a crack in the timing case where the deflector sprocket bolts on, and the casting broke so that the whole sprocket came loose. If this is the issue you have, then the only fix is to replace the timing case. A 1994-1995 M42 timing case is what you want because BMW eliminated the stupid sprocket that is basically a time bomb in our cars. To use the later timing case, you just need to get on RealOEM and order the proper case-to-block gasket (different than the E30 M42's) and the extra plastic guide piece.

        Good luck, for your sake I hope it is not #2!

        Comment


          #5
          Originally posted by bmwman91 View Post
          I had something similar years ago and it was, ultimately, the death of the engine.

          Two things to check:
          1) The upper bolt in the driver's side timing chain guide rail. It's the one that secures the threaded collar part to the cylinder head. Sometimes the threads in the head strip out and the bolt head rattles against the upper timing case cover. This needs to be fixed because the bolt will wear through the cover, as well as allowing lots of slop in the chain. The top bolt should be M6x45mm if the newer style plastic guide is installed, but a lot of times, the 40mm bolt from the old guide design gets reused and strips the head.

          2) This one is a bitch because you have to completely open up the timing case, and I do not know if you can even visually see the issue. Anyway, this is what happened to me. I had the buzzing at 3000RPM for about a year. It was coming from the front of the engine, I replaced all sorts of timing chain related stuff, and nothing helped. It ended up being a crack in the timing case where the deflector sprocket bolts on, and the casting broke so that the whole sprocket came loose. If this is the issue you have, then the only fix is to replace the timing case. A 1994-1995 M42 timing case is what you want because BMW eliminated the stupid sprocket that is basically a time bomb in our cars. To use the later timing case, you just need to get on RealOEM and order the proper case-to-block gasket (different than the E30 M42's) and the extra plastic guide piece.

          Good luck, for your sake I hope it is not #2!


          well shit sounds like I'm gonna be opening the timing case regardless which really sucks guess decisions need to be made now

          Comment


            #6
            Originally posted by Sladek View Post
            well shit sounds like I'm gonna be opening the timing case regardless which really sucks guess decisions need to be made now
            I know bmwman brought the doom and gloom, but you really need to isolate the location of the noise first or post a video for everyone to have a listen befoe you tear it down unnecessarily.

            Comment


              #7
              Originally posted by roguetoaster View Post
              I know bmwman brought the doom and gloom, but you really need to isolate the location of the noise first or post a video for everyone to have a listen befoe you tear it down unnecessarily.
              Yeah this too. Don't start pulling stuff apart until you get a video of the noise and some idea of where it is coming from. It can be hard to pinpoint these things.

              Comment


                #8
                Try a mechanic's stethoscope-
                I used the 'big screwdriver' method for 20 years,
                but in trying to find a flat cam lobe, discovered that
                they work far better. There's a diaphraghm that
                helps you narrow down WHERE the noise is coming from.

                For $8, it might help diagnosis. Because it really sucks
                to take it all apart and not find the problem, even though
                you know it's in there somewhere.

                t
                now, sometimes I just mess with people. It's more entertaining that way. george graves

                Comment


                  #9
                  https://vimeo.com/199909567

                  Comment


                    #10
                    https://vimeo.com/199910470
                    https://vimeo.com/199910560
                    sorry for potato cam

                    Comment


                      #11
                      it's hard to hear outside of the car, definitely most noticeable inside.

                      Comment


                        #12
                        That could be your exhaust rubbing against the body/mount point somewhere since I didn't hear it in the engine bay shot.

                        To me the engine sounds normal, some chain noise, maybe some lifter noise, but nothing from that video that would concern me. Then again, some phones/cameras are really great at noise reducing the heck out of exactly what you want to listen to.

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                          #13
                          hmm maybe I should try again under the car lol

                          Comment


                            #14
                            I can also try a gopro this weekend and see if that picks up the noise better

                            Comment


                              #15
                              Yeah, maybe it is the recording, but that M42 sounds normal. There was a slight "clanking" in your first video, at ~3500RPM. It sounded sort of like a loose catalytic converter core, or as Toaster said, something in the exhaust rubbing on the chassis.

                              Comment

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