Squealing bearing at engine start

[Redlands Mike]

I recently purchased a 99 911 Carrera. 6 speed manual. I love it.
I sometimes get a bearing squeal for a few seconds when starting the engine.
I think it may be a bearing from one of the serpentine pulleys.

[FPB111]

It might also be normal if it is the Air Injection Pump. The pump runs for ~20-40 seconds on cold start to light up the cats quicker.
It lives right by your left knee when you are standing at the rear of the car gazing into the engine compartment.
Disconnect it for 1 cold start and see if the noise is still there. It will throw a code (CEL) if you leave it disconnected too long. When they start to go bad they sound like a skill saw. Sometimes you can save it ($1500) by cleaning it out when it gets really loud. They are easy to remove from the car, loosen three screws, disconnect the connector and hose.

[DaveBerry]

Could it be the IMS bearing about to blow, costing you your engine?

[FPB111]

Dave, Get Real!

[JFP in PA]

Originally Posted by DaveBerry

Could it be the IMS bearing about to blow, costing you your engine?

More likely, it is the Bendix drive on the starter that is sticking momentarily on start up, which can make that type of sound. A common and easy DIY fix item, do a search, been covered many times……….

[FPB111]

http://www.renntech.org/forums/topic...post__p__84676 courtesy Loren:


"Auxiliary air Pump
To reduce pollutants contained in the exhaust gas during the warm-up phase and to achieve the emission limits of the roll test in the USA, USA vehicles have a secondary air system. For this reason, an electric air pump has been mounted on the left-hand side of the engine compartment. This pump is activated by the DME control unit and blows the additional air through air ducts to the discharge valve. A pneumatic switching valve which is closed when the secondary air system is inactive thus preventing the flow of additional air is installed between the air pump and the discharge valve.

Functioning
If the engine is started in a temperature range between minus 10.5° C and plus 45° C, the secondary air system is activated for a period of time dependent on the start temperature (min. 50 seconds, max. 179 seconds).

The secondary air system is only activated if the following engine-related operating conditions apply:
- Engine load (TL) between 0.7 ms/rev, and 4.7 ms/rev.
- air mass (ML) not greater than 300 kg/h
- Engine speed between 680 rpm and 2,800 rpm
- Altitude adaptation factor greater than 0.76 corresponding to less than 2,400 meters above sea level."

I remember another post as well that explained the running of the pump after cold startup (example at stop light after warmed up), but my guess is in the functioning sections, if those conditions apply then it will run, as I and others have observed.

[Redlands Mike]

Originally Posted by JFP in PA

More likely, it is the Bendix drive on the starter that is sticking momentarily on start up, which can make that type of sound. A common and easy DIY fix item, do a search, been covered many times……….

That is a possibility. Thanks for the heads up. i will do a little search in that direction.

[craig722]

Just cruising thru this forum and noticed this post from Wayne. Sounds like a match to me.
I'd park it until you can rule this out.

http://forums.pelicanparts.com/porsche-996-997-forum/543614-if-you-think-ims-bearing-failures-all-myth-then-check-out.html