Hissing Sound from Driver's Side of Engine

[Goombatz]

Specs: 2001 Boxster, 2.7L, 5-speed Manual, Approx 80k miles.

I noticed a hissing sound coming from the driver's side of the engine - it's much more noticeable on the driver's side than the passenger's side. It sounds like air leaking from a tire or balloon. It's pretty loud. I can hear it when I'm driving approximately 35mph. The hissing sound is also noticeable when the engine is idling.

The engine runs great, smooth idle, no loss of power, no check engine light.

I don't believe it could be the Air Oil Seperator (AOS) because that is located on the passenger's side of the engine but, I'm not an expert.

From what I discovered in this forum and others - it might be the AOS.

Within the last 12 months, I performed all the following: replace spark plugs & coils; Oil change; MAF cleaning; replace air intake filter, replace polyrib/serpentine belt; replace cabin filter.

I know the AOS was replaced about 40k miles ago.

Any other ideas or input would greatly be appreciated.

[wvicary]

Is it possible that you are just hearing induction noise due to the engine intake is on the drivers side?

[Goombatz]

It turns out that it was a failing Air Oil Separator.

I had to take my car to the mechanic so he can diagnose the problem. I'm also having him do the work which really bums me out because I would much rather do it myself. I'm so busy with work that I don't have any time to spend.

[logray]

You did the right thing and having it diagnosed by a professional. The good thing is, this is an inexpensive part which is not terribly difficult to replace. Let us know how the repair works out.