Announcement

Collapse
No announcement yet.

Crank / Balancer interface worn - anybody else seen this? Fix?

Collapse
X
Collapse
 
  • Page of 2
  • Filter
  • Time
  • Show
Clear All
new posts
Previous 1 2 template Next
    #1

    Crank / Balancer interface worn - anybody else seen this? Fix?

    I've been through it with this engine and I'm not going to bore you all with the story. I had cause to take it apart, and I'm pretty sure the balancer is not supposed to look like this.
    Click image for larger version Name: IMG_9009.jpg Views: 489 Size: 222.3 KB ID: 131101
    And I'm pretty sure the end of the crank isn't supposed to look like this:
    Click image for larger version Name: IMG_9011.jpg Views: 367 Size: 77.7 KB ID: 131102

    Before you ask - yes, it was torqued to spec. I certainly may have failed to clean the surfaces properly the last time I put it together. It also may have already been like this when I got the engine, it was a while ago.

    My local machine shop said that they don't have the necessary fixtures to machine these surfaces as perfectly square as they need to be. Has anyone else dealt with this? These two surfaces need a solid connection with each other, and now that they have basically polished themselves smooth I have zero trust that this won't continue to be an issue if I don't do something about it. If anyone has reasonable suggestions, or a recommendation for a machine shop in the SF bay area that can deal with this, I would love to hear it! Also just curious if anyone else has seen this.
    Tags: balancer, crank, harmonic, s54, wear
    #2
    That is weird, I agree. At the same time, a guy here (Pklauser) just posted a picture of his and it looks kinda similar, showing a wear pattern around the perimeter. https://nam3forum.com/forums/forum/m...ressions/page4

    The dowel pin should prevent it from rotating and I don't see any obvious signs of wear at that interface. So if it's actually caused by sliding it must be some very microscopic movements.

    If you are truly worried about it - you can replace that part. It's separate from the crank. Just remove the little bolt in the middle and it comes right off. There is another dowel on the back side between this piece and the crankshaft so don't forget that too. You will need to remove the vanos and exhaust cam sprocket to give enough chain slack to remove it. https://www.ecstuning.com/b-genuine-...t/11211401036/
    • Likes 1

    Comment

      #3
      Can't comment on the severity or fix for this, but my crank looks the same.

      Pretty sure it had never been apart before I messed with it and it hasn't given me any issues sooo...

      Edit: Damn, the sprocket is only $112. I thought for sure it was going to be a lot more money.
      Last edited by heinzboehmer; 10-10-2021, 10:31 PM.
      2002 Topasblau M3 - Coupe - 6MT - Karbonius CSL Airbox - MSS54HP Conversion - Kassel MAP - SSV1 - HJS - PCS Tune - Beisan - MK60 Swap - ZCP Rack - Nogaros - AutoSolutions - 996 Brembos - Slon - CMP - VinceBar - Koni - Eibach - BlueBus - Journal

      2012 Alpinweiss 128i - Coupe - 6AT - Slicktop - Manual Seats - Daily - Journal

      Comment

        #4
        The dowel pin hole seems to be enlarged and loose. If this is true then you might need a new one.

        Comment

          #5
          Is that a hairline crack in the balancer dowel pin hole?

          Comment

            #6
            It looks like it was run without the dowel pin for a period of time. I'm not 100% certain but I don't think you'd get those long scoring arcs with only a little bit of play in the dowel pin hole.
            '05 M3 Convertible 6MT, CB/Cinnamon, CSL Airbox&Flap, PCSTuning, Beisan, Schrick 288/280, SS V1's & 2.5" System, RE Stg 1&SMF, KW V2, CB PS, Apex EC-7R

            Comment

              #7
              It looks like it's moving slightly from the enlarged hole. Might want to consider pulling, check and replace the rod bearings too if you've been driving the car hard.

              Comment

                #8
                The radial elongated hole in the vibration damper is normal though does appear light damage in the hole tangential direction from the movement (dowel is a locator only), the gear can be replaced for about $100 or through surface grinding (cheaper) or you may be able to lap it yourself on a surface plate a fine sandpaper after you remove the dowel pin but there may need to be too much material removal to clean it up adequately its hard to tell from pic. You would want to address the surface on the vibration damper as well so you have a good uniform surface for the friction surface as that's how the load is transferred. I would take it to a machine shop and have them fix it as new ones are very expensive like $1,000
                Last edited by digger; 10-11-2021, 05:56 PM.

                Comment

                  #9
                  Originally posted by digger View Post
                  new ones are very expensive like $1,000
                  Dang, I had to check you on this and you're right. Wow.
                  403 Forbidden
                  https://www.ecstuning.com/b-genuine-bmw-parts/vibration-damper/11237834425/?gclid=Cj0KCQjwwY-LBhD6ARIsACvT72OsUpvxXhsz9qWSJrJ5d53YS0YJDlRjyxM2Agm5C_b8angVaqdXxlwaAsXtEALw_wcB

                  Comment

                    #10
                    Originally posted by cobra View Post
                    That is weird, I agree. At the same time, a guy here (Pklauser) just posted a picture of his and it looks kinda similar, showing a wear pattern around the perimeter. https://nam3forum.com/forums/forum/m...ressions/page4

                    The dowel pin should prevent it from rotating and I don't see any obvious signs of wear at that interface. So if it's actually caused by sliding it must be some very microscopic movements.

                    If you are truly worried about it - you can replace that part. It's separate from the crank. Just remove the little bolt in the middle and it comes right off. There is another dowel on the back side between this piece and the crankshaft so don't forget that too. You will need to remove the vanos and exhaust cam sprocket to give enough chain slack to remove it. https://www.ecstuning.com/b-genuine-...t/11211401036/
                    The movement would have been very small. The engine had a noticeable harmonic vibration when decelerating through the 5-6k RPM range, it was well over 100 Hz. I'm confident these are related.

                    I knew the nose was separate and replaceable, I had no idea it was that cheap, I went ahead and ordered one. Thank you for that!

                    Comment

                      #11
                      Originally posted by heinzboehmer View Post
                      Can't comment on the severity or fix for this, but my crank looks the same.

                      Pretty sure it had never been apart before I messed with it and it hasn't given me any issues sooo...
                      Curious - do you have a single mass flywheel?

                      Edit: Damn, the sprocket is only $112. I thought for sure it was going to be a lot more money.
                      Me too! This fixes half of my problem. :-D
                      • Likes 1

                      Comment

                        #12
                        Originally posted by sapote View Post
                        The dowel pin hole seems to be enlarged and loose. If this is true then you might need a new one.
                        You are not wrong. Or, to have the hole drilled slightly larger, and a new dowel made. Either way, can't really leave it like this.

                        Comment

                          #13
                          Originally posted by BubbaTree View Post
                          Is that a hairline crack in the balancer dowel pin hole?
                          No it's actually a little piece of debris. And now I'm looking at the dowel, and seeing a similarly shaped mark, and wondering if that's the cause of all my troubles here. Good eye.

                          Comment

                            #14
                            Originally posted by jbfrancis3 View Post
                            It looks like it was run without the dowel pin for a period of time. I'm not 100% certain but I don't think you'd get those long scoring arcs with only a little bit of play in the dowel pin hole.
                            I think when the rotation is caused by harmonics at a (relatively) high frequency, it can make a wear pattern like that. But you're right it looks like it was just spinning.

                            Comment

                              #15
                              Originally posted by enjoy_m3 View Post
                              It looks like it's moving slightly from the enlarged hole. Might want to consider pulling, check and replace the rod bearings too if you've been driving the car hard.
                              I actually have the entire engine apart, and most of it is at a machine shop for proper measuring. And yes, I was beating the snot out of it. 😀

                              Comment

                              Previous 1 2 template Next
                              Working...
                              X