My '04 Boxster w/tip makes a whistling sound starting at about 1800 rpms. Must be at a steady speed and it is continuous until you let off the gas and it stops instantly when the rpms drop below 1800. Any ideas?

Thanks

 

vacuum leak

 

Any immediate culprits come to mind? or do I just searching for loose hoses?

Thanks

 

could be any culprit...check all the small hoses on the top of the motor and on diaphrams/servos...look for loose hoses or small cracks as they can split when they get old

 

OK

Thank you very much.

 

I also have a whistling/screeching sound at idle on my 06 CS. At first thought it was the water pump. Turns out it was the Air Oil separator. Easy way to diagnose this was to remove the oil filler cap , while the car is idling. Sound goes away immediately (and I could feel the strong vacuum while removing the cap) I'll be replacing it as soon as I can get my hands on one.

 

I've replaced the air oil separator and the sound is gone .
Part cost just over R1000 (about $100) at Porsche Jo'burg.
I attached a pic of the removed part.
Was quite an easy swap, with the most difficult part being removing the spring pipe clamp on the small pipe that connects underneath the separator, I actually eventually disconnected it on the side closer to the engine and replaced the spring clamp with a jubilee clamp that I could fasten with a screw driver. The other pipes used quick release connectors which come off quite easily. Just 2 bolts holding it on ,both could be accessed from the top, actually I did the whole job from the top, it wasn't even necessary to jack up the car.
Quite happy it wasn't something serious like a water pump or clutch release bearing , which was my first thought when the sound started.