Where does all the gunk under the shroud come from?

[ErrorMargin]

Where does all the gunk around the intake ports come from?

Is it just from air being sucked in? I would have thought the fan would put positive pressure on there.

I don't see an obvious oil leak that would cause this.

Is this normal?

[mepstein]

Light film of oil and dust. Fan pulls it in. Oil film traps it. Pretty normal on these air cooled engines.

[ErrorMargin]

Originally Posted by mepstein

Light film of oil and dust. Fan pulls it in. Oil film traps it. Pretty normal on these air cooled engines.

Seems like an area with no obvious source of oil, unless...

Could this be the result of:

1. The aerodynamics of the car sucking air (and dirt) down through the shroud around the intake runners.
2. The intake runners have small leaks and the oil breather is pushing oil into the airstream which leaks out the intake runners?