Thx in advance. I was previously a brand new Cayman 2007 driver, but then switched to a more classic 996 C4. (Yes, I like the 911 better!) My 996 has a noise upon startup and need to know if abnormal. It's on just for startup + 60-80 seconds. Sounds electronic + mechanical, high pitch/very high frequency metallic grinding - perhaps a pump of some sort? It's under the motor hood. Is this normal and does anyone know what it might be? I have no other symptoms...just want to get ahead of a failure of some kind if abnormal.

 

It could be the SAI (secondary air pump). It's emission related and runs for a couple minutes after start up. It sits in the left side of the engine bay, just in front of the left rear lights. Maybe it's starting to go out if you have a high pitched whine.

 

My '99 C2 does the same thing. It sounds like a fan or turbine for about 90 seconds after starting when cold. Once the engine is warmed up it's not there. It has never given me any problems. I use the noise as my cue for letting the engine warm up before I drive.

 

"It could be the SAI (secondary air pump). It's emission related and runs for a couple minutes after start up."

^This^ is a pretty good bet. This being said, while fairly common, it shouldn't be considered "normal". Apparently it's a pretty simply DIY to remove the pump, take it apart, lubricate the bearings (they get dry which is what leads to the noise) put it back together and reinstall. Do a search here, on Rennlist and Renntech (I don't remember where I read it, but I know it's somewhere) Good luck

 

Good to know it can be serviced/lubed. I figured it would need to be replaced. Thanks!

 

Yeah, I don't know if you could get a shop to do it (or if it would be cost effective) but if you're up for the challenge, you can probably save a few bucks...