diagnosticator1

Find the DV located below the passenger headlight, between the turbo outlet hose and the radiator end tank. Follow the small vacuum hose that is connected to the top of the DV, up to the other end of that vac hose, at it's connection to the (or Intake manifold) N279 solenoid valve under the intake manifold. Now, backup down the hose toward the DV, and where the hose is easy to get to near the front end of the manifold, cut the hose. Now, connect a vacuum hand pump and pull a vacuum on the DV diaphragm. You must be able to pull a vacuum of at least 20 in Hg, that does not leak away after achieving that value, without further pumping, for a minimum of several minutes. It there is leakage make sure your connections and the pump release valve are not leaking. If the diaphragm has a hole or is torn, you will not be able to pull a vacuum or it will leak off almost as fast as you can pump. After testing, use a 1/8" double hose barb to reconnect the hose at the cut point.

Yippers®

a torn valve diaphram would 'chirp' for only the first couple of minutes after a start. Since he described it as only ocurring when the car was either cold or allowed to sit (cool a bit) from fully warmed I would suspect something that is temperature dependant ...

diagnosticator1

It's true the descriiption of the noise suggests a temperature dependency, but the DV is suspect until ruled out. It is one step in a process of illimination.

bieny

my car (1.8t 1998) is doing exactly the same thing! started a few weeks ago, i thought it was the chain tensioner but its still the same after i put a new one on. Also did all the belts at the same time. but i cant find the noise, also im sure i can hear the turbo louder than before?