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Old 11-17-2008, 04:20 PM   #1
BobbyT
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Default Screech/Squeal on start-up

I'm getting a screech/squeal noise that occurs just on start-up for a second or so. I thought it was the alternator failing, so I replaced it. No joy.

The belts have about 20,000 miles on them. They are all correct Porsche OEM, and the tension is correct when checked with the Krikit tool.

When the belts are removed, the fan and alternator each rotate smoothly and easily. The fan blades are not contacting the housing.

The noise is still there with the fan belt sensor removed.

Any ideas on what to check next?
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Old 11-17-2008, 04:25 PM   #2
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I would change the belts anyway - because if they are glazed - it will happen..? Since the alternator is new - it's not the bearing..??

Hmmm..???

John
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Old 11-17-2008, 05:10 PM   #3
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That's what my belts did just before disintegrating! Only on start up and when very cold.
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Old 11-17-2008, 05:13 PM   #4
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Have you tried a belt dressing yet? I find that sometimes works.

Cheers,

Mike
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Old 11-17-2008, 05:14 PM   #5
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I'd have to guess belts.
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Old 11-17-2008, 05:38 PM   #6
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Mine does it after she gets a bath, it's the belts.
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Old 11-17-2008, 07:15 PM   #7
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Thanks, John,
I was thinking the same thing, but before I do that I think I will just remove the AC belt and see if the noise goes away. Maybe the AC compressor is getting ready to pack it in, rotational resistance is getting higher, and makes the belt slip just a bit on start-up. I'll let you know what I find.
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Old 11-17-2008, 07:20 PM   #8
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Okay, it's not the belts, or anything related. I removed each belt in turn, and then started the engine briefly after each removal, but the noise persisted, even with AC, fan, and alternator belts gone. The noise is a screech/squeal, about as annoying as sharp fingernails on a chalkboard, and seems to come from the top center of the engine, forward of the alternator. It lasts just a second or so. SAI pump? HELP!

Side benefit, I think I can change these belts blindfolded on a galloping horse.
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1995 C2 coupe six-speed, Guards Red/Cashmere
2000 Lexus RX300
2012 Mercedes-Benz E350

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1971 911T Targa silver
1972 914 tangerine
1977 924 copper metallic
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Old 11-17-2008, 07:22 PM   #9
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Is there a way to disable the SAI pump temporarily to see if the noise goes away?
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1995 C2 coupe six-speed, Guards Red/Cashmere
2000 Lexus RX300
2012 Mercedes-Benz E350

Fondly remembered:
1969 912 coupe silver
1971 911T Targa silver
1972 914 tangerine
1977 924 copper metallic
1983 911SC coupe guards red
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Old 11-17-2008, 07:25 PM   #10
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Quote:
Originally Posted by BobbyT View Post
Is there a way to disable the SAI pump temporarily to see if the noise goes away?

Blown SAI pumps sound like a high pitch whistle, or a screeching type noise.


If you wait 2min the pump shuts off, or if you have a Durmetric cable you can turn it off & on on demand. You can even turn it on with the engine off.
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Old 11-17-2008, 07:26 PM   #11
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maybe the steering pump and/or belt? Belt is ribbed, but worth checking...

It's right next to the SAI valve and close to the general area where you hear the noise.
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Old 11-17-2008, 08:33 PM   #12
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My Car does it too but i just put brand new belts in. I figure they just need to be tensioned some.
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Old 11-18-2008, 01:43 AM   #13
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I don't think it can be the power steering pump belt. Isn't it unlikely to make a noise when the car is still? More likely to make noise when the steering wheel is being moved? Also, the location of the noise seems to be more in the center of the engine, not on the right side, where the PS pump is.
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1995 C2 coupe six-speed, Guards Red/Cashmere
2000 Lexus RX300
2012 Mercedes-Benz E350

Fondly remembered:
1969 912 coupe silver
1971 911T Targa silver
1972 914 tangerine
1977 924 copper metallic
1983 911SC coupe guards red
2001 Boxster black
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Old 11-18-2008, 09:26 AM   #14
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I had that problem too... for me it was the fan roller belt.

http://p-car.com/diy/roller/
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Old 11-18-2008, 11:54 AM   #15
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I removed the fuse for the SAI pump (as well as the relay), noise still present. So far I know it is not the fan belt sensor, not the belts, not anything belt-driven. This is a puzzle...
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1995 C2 coupe six-speed, Guards Red/Cashmere
2000 Lexus RX300
2012 Mercedes-Benz E350

Fondly remembered:
1969 912 coupe silver
1971 911T Targa silver
1972 914 tangerine
1977 924 copper metallic
1983 911SC coupe guards red
2001 Boxster black
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Old 11-18-2008, 11:54 AM
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