The serpentine belt on our 98 E320 shows some strange wear on flat side (see picture below)
The spots on the rubber are quite soft. Almost like chemically or heat degraded. There also seems to be some wear at the edges.
Belt is OE and was replaced about 7 years ago by dealer (46k miles since).
Tensioner is new type.

Anyone else seen anything like that?

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5