screech at start-up

[txhokie4life]

99 996

I've only had this car for a little bit, so I've got limited data

I get a screech during startup.
Very distinct conditions.

Seems to be first thing in the morning -- haven't had it do it any other time of day.

Only after the engine fires up -- starter does its 2-3 cranks,
then screech -- immediately stops noise -- runs great.

Don't notice any other noise -- sounds good -- only have a running boxster
engine to compare too -- but they are essentially the same.

Start it any time during the day -- even if having sat for several hours
there is no screech.

appreciate any pointers

thanks,

Mike

[Rrrockhound]

This isn't specific to a 996, but whenever I hear a noise at startup that only occurs in the morning, I can usually relate it to morning dew or fog having settled on the belt(s) and pulleys. Do you park outside or inside? Does it get foggy where you park?

[rb101]

It most likely is the auxiliary air pump starting to go bad. It usually only runs for about 1 minute on cold startups.

[BYprodriver]

the noise you describe sounds like your IMS chain tensioner is leaking oil overnight. A new updated tensioner has a preload spring to minimize chain "flap" until the tensioner builds oil pressure.