glacier.996

Hi guys,
I have owned a 99 C4 manual since last June. Everything has been great, but overnight I started noticing a low-ish pitched whining sound, almost like a sewing machine or vacuum motor. Everything is stock accept an IMS retrofit from LN engineering. The only thing that I’ve done to the car is change the oil about a thousand miles ago, but the whine did not start immediately following.

Key points:
- Gets lowder/higher pitched when reved
- Is audible while driving and while revving in neutral or with the clutch in
- Does not change when warm or cold
- Does not seem to be speed related
- Can be heard while revs are rising and falling

I have attached an audio file, I started in first, shift to second, then go full throttle to third.

Thanks for any help, it is much appreciated.

sublm8

That sounds like an M96.

Anything else off?

ZuffenZeus

Is your wife or mother-in-law in the car when this occurs?

glacier.996

Nope everything else seems normal, only reason I’m worried is because it’s changed since I bought the car.

GC996

For some reason I can't get the clip to play. Doubt it's the clip. Probably my inability to use my new phone.

But the noise culprits are typically the SAI is starting to go (high pitched whine), or your power steering fluid is low (whuring that gets louder when you turn the steering wheel, or your belts and pulleys are making noises.

sublm8

As mentioned above - I’d check PS fluid level, belt and rollers, and water pump.

The audio file sounds to me pretty normal for a 5 chain, but the fact that you’ve noticed a change does warrant investigation.

Elumere

Cannot play the file either, but I had a whine develop when the fuel pump decided to go slowly.

Mike Murphy

Sounds normal.

You could pull the serpentine belt and see if it still wines, but only run the engine like this for 20 seconds. The belt is easy to remove.

Ben8jam

I too, have been chasing a mysterious, whining sound. I've eventually given up. Yours sounds maybe somewhat similar to mine?

911Dreamer

What is the normal whine sound of the M96? I had a friend in my car and he was like, sounds like your power steering is going and I was nope, its the engone sound lol

DBJoe996

These are small sports cars with a big *** flat six in the rear. Go stand next to Porsche race cars coming out of the pits. They all have a unique whine. I actually love the sound when I have the chance to really get into it.

Porschetech3

The "sewing machine sound" is a trademark of the early Porsche engines. On the 996 it is more pronounced on the early 5 chain w/ dual roller chains, that it is on the later Hyvo chains or 3 chain engines..

But your audio sounds typical, you need to record a better audio recording for a longer period of time under different scenerios, if you are genuinly concerned..

Like as mentioned the SAI pump, PS pump fluid level , idler pulley's , WP, ect are common causes of increased noise/whine...

Mike Murphy

I wonder if the oil change made the whine more pronounced. Different oil brands, even if labeled the same viscosity, are still different viscosities.