Hello everyone,
Is it normal? Now I can't unbolt the top 10mm nut, and I saw a brown colour plastic block beside it and infront of the pump housing...

Thank you
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Okay found it.
Obviously someone did the engine rebuild last time didn't do it right, the chain guide is install backwards, the right position is plastic cover the chain, but on mine the chain is exposed on the outside.
But what important is the engine still run fine, but with noisy chain....