I am in the process of putting the 240D engine back together and have run accross something I am unfamiliar with. On the spring for the oil ring on the Mahle pistons (set included pistons, rings, pins and clips) there is a yellow "sleeve" around the spring underneath the ring. It looks like it is permanent and also like it is made of plastic type of material. Is it supposed to stay on the spring? If possible I need an answer this weekend to allow me to continue with the assembly.
thanks

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Jim