Third-Reef

I have 135k on my 99 C4 it runs well, has a clean filter and sump but makes a bit more of the 911 whine than I think is normal. Wondering about changing the 4 and 5 chains and guides. JR recomended this on his site for the 5 chain motors over 40K miles. However no one ever mentioned it here. The parts are cheap and it looks like can be done with the engine in the car.

GLIDE

With that mileage, I'd say its a safe bet they are deteriorated.

Having done this a couple times, I would not even consider attempting with the engine in the car.... But I'm sure it can be done.

Macster

Given the expense of replacing the chains and guides (and tensioners too while you are there) you need to be sure the whine is not normal and is due to the items you seek to replace.

Whine is not a noise generally associated with chains/guides/tensioners in need of replacing.

Absent any chain guide composite plastic bits in the oil filter housing oil or filter element, absent any signs of tensioner o-ring material in the oil filter housing oil or filter element I think think the chains/guides/tensioners are not the cause of the whine.

BTW, I have had worn tires or misaligned tires be the source of considerable whine to the point one time I had the car in for suspected bad wheel bearings.

Third-Reef

What does make a M96 whine? I have checked out all the acessories, ran it without the belt, does not change with the clutch in. Used a stethoscope on the IMSB area. It is not strange noise, just the normal porsche flat6 whine but louder.

Schnell Gelb

Oil pump?
Try the stethoscope again and give us a hint of where the whine comes from.
Since you had the accessory drive disabled it can't be W/P P/S
The SAI isn't running continuously is it ? Remove fuse to disable- you'll get a CEL but ignore/delete.
Pilot bearing?