Mystery Part from Stihl Chainsaw

chainsaw

I opened the case of my Sthil MS311 chainsaw and found a recessed screw in the case, but I cannot find where it came from (saw wrench head for scale). It seems to be a something used to hold liquid, because of the rubber gasket. The saw ran fine for a long time (about a year). It's been acting up lately, not sure if this is the cause. By acting up, I mean it starts fine, but it seems like the chain isn't getting enough bar oil, causing the chain to bind up.

I searched though the parts list on the usual sites, but cannot find it.

Any idea what it is and where it goes?

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Best Answer

The rubber gasket is a vibration isolation mechanism, not a liquid holding mechanism, based on experience with the parts of my Stihl saw (different model but those parts are similar.) All the mounting points between the handle/frame and the saw motor use those rubber-mount nuts.

While lacking a convenient exploded parts diagram, the manual I found does have a list of things to check when the bar is not getting enough oil.

https://stihl.partsmartweb.com/Catdata/EMP_IMG/STGSTH/Images/SERVICE/00590215.PDF