Originally Posted by krozet
....but it's more like burned oil... Any guess as to what this build up is? I am going to clean it and put it back on. Why would the PO not have a foam element?!?! Any number of nasty things could have been pulled into the engine...
As for the Crankcase breather, it has a couple drops of oil on the shelter plate but other than that it is clean.
The build up is likely rubber dust from belts oil soaked from engine fumes and baked on from residual engine heat. That's my guess.
The PO likely had a "professional" look at or work on his engine. They often remove elements rather than clean them. It helps the engine breath but as you point out filtered air is better than non-filtered air even though it isn't much of a filter. Silencer is the correct term for that bit of plastic.
I would expect new modern engines to have air filters but maybe not on the small ones. Filtering the air was one of the biggest steps in extending engine life.