I have occational "bird twittering" when I start engine cold. They disappear quickly after a minute or so. But they come back occationaly, especially after after a hard acceleration or revving when engine return to normal or idle revs.

I am pretty sure its not the belt since its brand new (3 months) and put on by Porsche Center. It's correctly aligned and all. My second guess was the water pump but I have a vague memory reading somewhere that signs of a bad alternator is noise and twittering after engine revving.

I have listened with lid open but its really hard to identify where the noise comes from. I will anyhow ask Porsche Center when its in for changing outer tie rods but I dont want them to change alternator just because I think thats it.

Any ideas from someone with similar noise?

 

I'm not familiar with the symptoms of a failing alternator. What I would do is take off the accessory belt and rotate each pump and pulley to see if you can hear or feel anything. That would isolate the problem because it is much more difficult to do when everything is moving at the same time.

 

I have an automotive stethoscope that I use for things like this. It as a thin metal rod on it that you can poke into fairly tight locations and listen to the noises coming from things like water pumps and alternators. It was cheap - probably $10 at an auto supply place - and works really well for isolating things like noisy bearings, etc.

 

Yep the mechanics stethoscope, just don't get it too close to the pulleys and belt! HA! Don't ask how I know. Also, taking off the belt and giving each pulley a spin, a tug and a wiggle (that's what she said). Might give you a clue to which accessory's bearings are potentially going. I have heard water pumps make high pitched chirps. My 996 had a bearing noise which ultimately ended up being the water pump.

 

Thanks guys! I will definitely go the stethoscope route first.

Ha, ha ChicagoSpeed996 - that was EXACTLY what I was fearing: you stand there with headphones on leaning in the engine bay and then the stethoscope catches the belt, pulls the head which hits the intake, fingers are twitching and are hooked between belts and pulley. I can do that!

A neighbor of mine actually lost the tip of his finger while trying to put potato flour on a squealing belt. Finger was stuck between belt and pulley.

 

To trouble shoot those noises, use a sprayer and spray water on the belt when it's running (only a few squirts are enough). If the noise changes the it's the belt. If not it's the pulleys. Take the tension off the belt and spin the pulley one by one.

 

Don't rule put out the new belt making noise. Happened to me on another vehicle. Drove me crazy thinking it was alternator or intermediate pulley bearing.

 

I had a new Porsche belt start squealing after about 6k miles. Only did it on start up and for the first mile of driving. They do weird stuff. Belt looked fine when removed.