Is it normal to see motor oil in the vacuum lines of a 2005 Honda Accord 2.4L Manual Transmission? Aside from a mildly rough idle when under load (A/C on), the car does not seem to have performance problems.

I noticed oil residue inside the vacuum line coming from the top of the intake manifold and routed to the AC pump. I haven't inspected any of the other lines yet.

Thanks.

 

There should be a PCV line for the PCV system that runs from intake manifold to engine crankcase. PCV valve will be at valve cover or intake manifold end.

Another line runs from valve cover to air intake duct to allow filtered air to enter the crankcase.

Oil in the PCV line is not unusual as crankcase vapor w/ oil is being pulled from crankcase into intake manifold.

good luck