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

[enjoy_m3]

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.

[jbfrancis3]

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.

[BubbaTree]

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

[sapote]

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

[heinzboehmer]

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.

[cobra]

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/

[yellowltd]

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.

And I'm pretty sure the end of the crank isn't supposed to look like this:


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.