The inside of my M54 timing chain cover has a vertical rib above the crank shaft hole. The rib is about 1/8 inch [ 3mm ] thick and is located in the center of the loop of the timing chain. The rib protrudes from the cover towards the engine block, and it's vertical between the two plastic chain guides. Nothing comes in contact with the rib. The corner of the rib has broken off, so I don't know if I need to replace my cover or not. I don't understand why the rib is there, or what it's used for.

Does anyone know what this rib is for?

I can't attach a picture, but if you search for "BMW 1702809" on ebay, you can see the cover with the rib on the inside.

Thanks,
Ken