996 Turbo / GT2 Turbo discussion on previous model 2000-2005 Porsche 911 Twin Turbo and 911 GT2.

screaming noise from hydraulic system

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Old 05-18-2004, 05:59 AM
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screaming noise from hydraulic system

I have a two month old Turbo-Cab with x-50 package.
After driving hard, e.g., bursts of speed near redline my engine makes a VERY loud schreeching or shrieking sound while I am slowing down in second gear. It only occurs while slowing down and it generally ceases when I depress the clutch to stop.
My dealer, Bill Cook in Detroit had a Tech go for a test drive. He exited while the car was making the noise and opened the hood and discovered that the noise was escaping pressure fron the hydraulic steering/brake cylinder.
The dealer has asked for help from Porsche's Tech line but has asked me if anyone I know has a similar problem.
The dealer believes that it may be a design defect inherent in the hydraulic pump.
Anyone else have the noise ?
Jim Hiller
 
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Old 05-18-2004, 08:20 AM
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I had a similar sound, and it was traced to low hydraulic fluid. Have the dealer check it out if he hasn't already...
 
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Old 05-18-2004, 02:52 PM
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This is pretty common most people don't really notice it, only noticeable when windows are down. And going very slow, almost like an electrical noise/whine. Sound is probablly more noticeable in a cab due to top down or thinner acoustics. If it's the same noise it's normal. goes away when the clutch pedal is pressed.
 
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Old 05-18-2004, 08:41 PM
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Have the same sound on my '02 Turbo. Dealer said it's the nitrogen valve vibrating under pressure in the power steering/clutch hydraulic system. Very hard to get to it (motor must be dropped) and the replacement may do the same thing.
 
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Old 05-19-2004, 03:40 AM
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I'm satisfied that the noise while common is absolutely not a "normal" noise. I had someone pull up next to me at a light and ask if my engine was "blowing up" !
I'm certain it is far worse in a cabriolet, especially when the top is down. If any of you are able to keep the engine making the noise after stopping as I have you must cover your ears when you open the hood because of the loudness.

I have made a demand pursuant to Michigan law that the car be replaced or that my money be returned.

My wife's car, a brand new Cayenne is also in the same dealers repair shop because her back doors will not latch.
I have a GT on order. Let's see how Porsche responds to this obvious case of design problems.

If they turn their back i will cancel my GT order .

Jim
 
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Old 05-19-2004, 03:55 AM
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I had a similar sound, and it was traced to low hydraulic fluid.
Bingo. Same here and on two other turbos I know of.
 
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Old 05-19-2004, 07:54 AM
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Originally posted by oruehr
Did the noise stop after more fluid was added?
100%.
 
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Old 05-19-2004, 08:38 PM
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Ray M,

Was the system low on fluid yet read full on the stick? Mine is showing full, but I was wondering if there's still a chance the system's low. Air-bound, maybe? TIA
 
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Old 05-26-2004, 05:11 PM
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Finally received a response from Porsche Tech about the noise.
They have authorized a 2 step approach beginning with a new cap on the hydraulic pump accompanied by a flush of the hydraulic system and new fluid.
If unsuccessful they authorized a pump replacement.
Evidently this screaming or screaching noise is known to them. It must be very common and now more audible with Cabs.
I am very suprised that more people have not complained. It is very very intrusive.
Jim
 
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Old 05-29-2004, 11:11 AM
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Got my car back from Bill Cook Porsche today. They did the first of the two suggestions from Porsche to rid the Car of the noise.
It didn't work. The first was a drain and refill of hydraulic fluid and a new cap.
Within two miles the car was screaming again.
Next step is replacement of the Pump.

I think that in the end Porsche will ignore the problem because it does not impact driveability.

I think a $160,000 car shouldn't sound like it has a slipping alternator belt.

If it is not resolved to my satisfaction I'll cancel my GT order. With the TT this problem is an irritant. With a $450,000 car it would be a tragedy.
 
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Old 05-29-2004, 06:25 PM
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I have read it. I'm hoping to enlist others who suffer from the same problem. Porsche denys that the noise is either a problem or a suitable issue for them to consider.
If other like me have the same problem and it remains despite the two "fixes" I want them to know. I certainly don't want to sue them but persuade them to fix the damn noise. It is irritating as Hell for the car to screech every time I slow down.
Jim
 
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Old 05-30-2004, 06:59 AM
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I have a 2003 TT and had the same problem last year. It first started after hard driving at a DE. It would only happen at low speeds, 1st, 2nd gear, and would continue until I turned the car off. It would only sometimes reoccur. It happened off and on for a couple of months. I haven't heard it since last year. I now have 14K miles with no reoccurance.
I Would be curious as to the cause. It was a VERY LOUD screeching, similar to a slipping fan belt. It wasn't a belt.
 
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