[Jack]

Just a thought…Toyota uses a lot of alloys that form protective oxide layers…and sometimes destructive oxide layers, such as the frames on Tacoma’s a while back. At any rate, I see similar excess dust in my Highlander and it seems like dust from interaction of the belt and the upper toothed cam pulleys. They seem to develop an oxide layer outside the belt travel area…so I suspect the dust is from the fringe of the belt on those upper cam pulleys. I had only done Honda timing belts before…never saw anything like this behind a Honda belt cover.

[Author]

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