2002 Porsche Boxster chirp squeeze noise coming from engine

Noises problem
2002 Porsche Boxster Two Wheel Drive Automatic 80000 miles

Hello,
My Boxster is making a chirp squeeling noise
and the sound comes from the engine vent.
The noise happens every few minutes
and it doesn't matter at what speed I am
going & if the car is on and in the Park, I can
still hear it. I brought it into the dealer and they
checked it over and can't figure out what is happening. ( I asked if it was a transmission problem as the car is a tiptronic trans. So if that is the
problem it would have to be completely replaced
rather than taken apart and fixed.)
Right now it is just a noise that I don't like,
but would hate for it to mushroom into
something larger.
Not sure if this is helpful or not but I had
the engine's rear main seal done about a year
ago and have had no issues since.
Thanks for your help. There were no fluids
leaking of any kind at the time of inspection.
ROSE