Oil residue air intake near throttle body (w124 m104)
 

Hi there,

I noticed today that there is some oil residue inside the air intake (just before the throttle body). It seems to be coming from the 2 mounting holes in the air intake plastic part that sits on top of the valve cover (so seems like oil from inside the cylinder head is escaping from the 2 mounting holes and into the air intake).

This has left a thin film of oil reside all along the inside of the air intake right into the throttle body.

I can't remember and / or imagine this is normal so any ideas on what's wrong?

normal.I clean mine once a year with gasoline to get film out.

This might a dumb question, but it seems like the oil gets in from the two holes in the valve cover and into the 2 mounting points on the air intake (the part that passes over the valve cover).

So should those holes be plugged, or is this the intended design? And if it's the intended design, why is it designed to allow oil to creep into the air intake?

Thx

This is the crankcase vent and should not be plugged, some oil residue is normal but not a lot of oil.