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My Boxster is making a screeching sound that does not always occur. The car is at the 80,000 mile mark and my query of the site suggest the AOS can produce that noise. I have opened up the engine bay to help locate the noise but it does not always occur. I have drove the car last night with not luck.
What I did notice is a slight hiss when pressing the accelerator that immediately drops off… like the opening of the butterfly on a carburetor, so it may be normal. The sound when it does appear sounds like a belt slipping but is not consistent with revving the engine. I initially suspected a clutch or throw out bearing… but everything performs as normal.

Also… the top of the engine air chambers has a light build up of oily dirt, I plan to use a Kleenex or mist to attempt to determine if there is any vacuum leak.

There is no smoke coming from the exhaust.

I also planned to open the air channel to clean it and check for oil in the air way.

Any ideas?

Thanks in advance.

My Boxster is making a screeching sound that does not always occur. The car is at the 80,000 mile mark and my query of the site suggest the AOS can produce that noise. I have opened up the engine bay to help locate the noise but it does not always occur. I have drove the car last night with not luck.
What I did notice is a slight hiss when pressing the accelerator that immediately drops off… like the opening of the butterfly on a carburetor, so it may be normal. The sound when it does appear sounds like a belt slipping but is not consistent with revving the engine. I initially suspected a clutch or throw out bearing… but everything performs as normal.

Also… the top of the engine air chambers has a light build up of oily dirt, I plan to use a Kleenex or mist to attempt to determine if there is any vacuum leak.

Any ideas?

Thanks in advance.