This howling sound occurs after cold startup. I noticed it this winter. Garage and outside temperature was 52 degrees. On colder days the sound comes and goes for about 1 minute before it stops. On this startup it only happened once. Hitting the throttle does not change the pitch. Any ideas? http://vtgstudio.com/996tt/996tt_Sta...e_seq_160K.mp3

Thanks Gents.

Vince

 

Just to clairify, the noise you're referring to comes on at 16 seconds into the video?

If so that is loud, and only lasts 2 seconds.

 

Yes, right after engine start ...the 2 second howl.

 

belt/rollers

 

Could be the oxygen pump kicking in - its to keep the emissions in check, the howling could just be resonating through the exhaust.

 

The oxygen pump could be it, since the sound does not change when I hit the throttle. I’m thinking that a pulley or belt would probably change pitch when the RPMs increase … of course I could be wrong. Also, if I cut the car off and immediately restart it, the sound does not occur. It only happens on first start after a day or so of sitting. I’m taking it in this week and will report back on what the shop says. The other thing is that the colder it is outside, the more frequent the sound is during the first minute of startup.
Thanks all.

 

Make sure you have them check the idler pulley BEFORE they swap the AIR pump or other parts. At least a couple of guys here had the bearing on that go and mechanics swap the AIR only to still have a noise! The bearing for the idler is cheap or you can swap the whole thing - there's a thread here about it somewhere...