ICohen424

Just a couple of days ago I noticed at a stop light that my car has a high pitched, constant, whining sound.
I realized that the sound went away after I pressed the clutch once or twice.

It usually comes back after a couple of minutes (or less) of driving... then Im able to hear it at lower speeds and lower RPM (because less wind and engine noise to cover it up)

The sound doesn't seem to be effected by engine speed or vehicle speed, its just a constant. It will always go away after depressing the clutch twice, but sometimes just once.

I dont know the characteristics of a failing clutch, but Ive heard that the clutch would feel very hard to press in, which is not the case in this car.

Does anyone have any ideas or suggestions?

Vehicle: 2002 Porsche 911 turbo - x50

Thanks!

XR4Tim

Could be a throw-out bearing noise.

ICohen424

Thanks for your reply.
Does the noise mean theres a problem or is it just the noise it makes?
How do I find out for sure?
What is involved in changing such a bearing?
Thanks!!

JG 996T

Search turbo forum - sounds like power steering pump issue. There is a Porsche TSB - copy attached.

ICohen424

After reading your attachment, I completely agree with you... but how is the steering related to depressing the clutch?

JG 996T

My understanding is that the power steering system and clutch system are connected (don't know the precise mechanics)

ICohen424

I didnt want to go on guessing any longer so I visited my local shop (who specializes in Porsches).
I showed him the whining sound and he was puzzled by it. I showed him the print-out of the above PDF so he began looking around.
He found that the power steering reservoir was almost completely dry! I just got the car a couple of weeks ago and just assumed the fluid was fine... Not very smart on my part.
We filled it up and so far no sound... but I only drove a couple of miles since.
Ill follow up after some more mileage with the outcome.

Hurdigurdiman

Give the whole car a good once over before you do many more miles. Tire pressures, coolant, Change brake fluid & bleed the brakes, change the oil, filter, and air filter, serpentine belt, Seems that the PO failed to maintain the car if he let the power steering fluid go low. Check the brake pads when you have the wheels off. It's pretty cheap straight forward DIY work.

jasper

Hhmm. My power steering reservoir went dry once. I topped it up and it went dry again. Then I noticed the puddle of fluid forming in the belly pans under the steering rack. After a few month of denial I finally replaced the steering rack which was leaking badly.

$700 for the part and three hours labour. Looking back I should/could have bought a rebuilt rack for half that price.

The moral of the story though is that power steering fluid does not disappear for no reason. Keep checking the level and address the leak or you'll burn out your pump - and then it gets really expensive.

As far as the clutch being connected to the power steering... I don't think so.

ICohen424

The local porsche dealership to where I bought it did a PPI and gave it a clean bill of health only 2 weeks ago. I didnt feel too confident in them but I went with it.

Im going to check most of the basics out myself but I already scheduled an appointment with a local, well trusted, shop for them to do a full check.

Thanks for your input and advice!

ICohen424

Very interesting... I didnt think the fluid would be caught under the car. Ill have that checked out.

I agree that the steering connected to the clutch seems illogical... but take a look at the PDF above... and the mechanic explained it to me... so Im left to believe it.

ICohen424

The whine is back.
Looks like its gonna have to go to the doctor for some repair after all.

Macster

The noise symptom is similar though not as severe as that from my 03 Turbo.

The cause is I've been told a relief valve in the power fluid system that provides power assist to the steering and the clutch.

The clutch of the 996 Turbo is power (hydraulically) assisted.

When I roll up to a stop I can hear the noise. I can make it go away by pressing down on the clutch pedal then releasing it.

The Porsche techs tell me the cause is a noisy valve that is part of the power steering fluid tank.

The labor to replace this is not that high. The problem is the valve is not available separately, but comes with the tank. The tank costs around $1000. (I was told it was a 'very fine tank'... for that kind of money it should made out of gold!).

Anyhow the techs told me there's no harm in ignoring the noise.

In your case the loss of fluid suggests another problem.

The clutch slave cylinder can go bad and fluid is somehow routed from the power steering reservior to the clutch fluid reservior located under the plastic panel under the front trunk.

This went bad in my car and one sign was there were fluid stains on top of the panel. The stuff is Pentsosin and can attack rubber so if there is any of this fluid leaking it wants to be cleaned away and teh source of the leak fixed, pronto.

While you are at it you might check the clutch accumulator. This went bad in my car and shortly (week or so after) the clutch slave cylinder went bad. I do not think their failures are related, they are just a weak point, couple of items in the car.

Anyhow. with the engine off, after just being shut off after being run at least 20 seconds at idle and without turning the wheel, you should be able to fully depress the clutch pedal then release it and repeat this for 25 or more times before the pedal gets stiff/hard to depress.

Next, once the pedal gets hard to depress start the engine and let it idle for 20 seconds. Do not turn the wheel. Shut off the engine and repeat the test. This tests that the power circuit can properly replenish the pressure in the accumulator.

Another possible concern, at least with Boxster, I do not know if the Turbo is at risk from this, is a pressure relief valve in a power steering line can fail.

The result is the power steering rack sees high fluid pressure which will force fluid past the rack seals.This fluid will not leak out to where it can be seen, even with a close inspection of that area. Instead it is caught by the dust boots that cover the rack steering rod/seals.

I watched a tech squeeze one of these boots and it popped and fluid gushed out. He had already determined the problem. The rack was out on his work bench.

Anyhow, not only does the line with its valve need to be replaced, the power steering rack is ruined and the driver only suspects something when he hears a noise which turns out to be the power steering pump that has run low of fluid.

This often ruins the power steering pump and of course it needs to be replaced.

You need to get the car in to a shop that knows these Turbos inside/out and have all possible items I discussed above checked out and corrected.

Sincerely,

Macster.

ICohen424

Macster,
Talk about a thorough response!!!
Thank you VERY much for so much detail!!!
I have an appointment to have the car checked out on Monday... and other than a couple of short cruises this weekend, Ill be driving one of my other cars.

Again, thanks very much!

Chan668

Hi

I’m having the same issue with whining noise which can hear at lower speeds then when clutch is pressed it stops. Did you find out what it was? Car is 996 turbo s.