Screech/Squeal on start-up

BobbyT · 11-17-2008, 04:20 PM

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?

John D. · 11-17-2008, 04:25 PM

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

SC2993 · 11-17-2008, 05:10 PM

That's what my belts did just before disintegrating! Only on start up and when very cold.

Mike J · 11-17-2008, 05:13 PM

Have you tried a belt dressing yet? I find that sometimes works.

Cheers,

Mike

TheOtherEric · 11-17-2008, 05:14 PM

I'd have to guess belts.

Stealth 993 · 11-17-2008, 05:38 PM

Mine does it after she gets a bath, it's the belts.

BobbyT · 11-17-2008, 07:15 PM

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.

BobbyT · 11-17-2008, 07:20 PM

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.

BobbyT · 11-17-2008, 07:22 PM

Is there a way to disable the SAI pump temporarily to see if the noise goes away?

Stealth 993 · 11-17-2008, 07:25 PM

Quote:

Originally Posted by BobbyT

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.

cabrio993 · 11-17-2008, 07:26 PM

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.

Boeing 717 · 11-17-2008, 08:33 PM

My Car does it too but i just put brand new belts in. I figure they just need to be tensioned some.

BobbyT · 11-18-2008, 01:43 AM

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.

wolfgang1 · 11-18-2008, 09:26 AM

I had that problem too... for me it was the fan roller belt.

http://p-car.com/diy/roller/

BobbyT · 11-18-2008, 11:54 AM

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...

11-17-2008, 04:25 PM	#2
John D. Rennlist Join Date: May 1998 Location: Somewhere.... Posts: 9,210	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 __________________ '95 993 C4 '89 964 C4 (<- Jen's...) '88 911 Turbo '68 911 L (<- Jen's...) *Don't Panic* - it's just me, John D.(<- Jen's...) posting as me.... Team Geek & Sunday Driver for “Hey, Wait For Me Racing” Giving new meaning to the term *“Frozen Rotors”*

11-17-2008, 05:10 PM	#3
SC2993 Addict Rennlist Member Join Date: Sep 2006 Location: The Lone Star State Posts: 438	That's what my belts did just before disintegrating! Only on start up and when very cold. __________________ JK Bilstein HD's, H & R Springs, Euro Turbo Front Bumper, Scrape Bar, Fog Lights w/ Ducts, Clear Corners, XM Radio, MY 02 18" Wheels, Steering Rack Brace, Aluminum Gauge Bezels.

11-17-2008, 05:13 PM	#4
Mike J Addict Lifetime Rennlist Member Join Date: May 2001 Location: Vancouver, BC Posts: 5,935	Have you tried a belt dressing yet? I find that sometimes works. Cheers, Mike __________________ "Scarlett" - 1997 993 Arena Red Turbo - Sport seats, silver gauges, aluminum parking brake/shifter, 19" RUFs - and more to come. Gone but now living just down the street - 96 993 Polar Silver Targa Check out http://www.pcarworkshop.com

11-17-2008, 05:14 PM	#5
TheOtherEric Addict Rennlist Member Join Date: Nov 2002 Location: Chicago Posts: 8,960	I'd have to guess belts. __________________ His: 1995 993 C2, speed yellow. JRZs, RS sways, other go-fast parts. His & hers: 1994/5 BMW E36 M3 race car, NASA GTS3.

11-17-2008, 05:38 PM	#6
Stealth 993 Addict Rennlist Member Join Date: Oct 2007 Location: Tacoma, WA Posts: 4,833	Mine does it after she gets a bath, it's the belts. __________________ Mike S SIGN UP PNW 993's 1995 993 C4 is SOLD!

11-17-2008, 07:15 PM	#7
BobbyT Addict Lifetime Rennlist Member Join Date: Sep 2004 Location: CA Posts: 1,189	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. __________________ BobbyT #050110-5596 AKA bob@pelicanparts.com 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

11-17-2008, 07:20 PM	#8
BobbyT Addict Lifetime Rennlist Member Join Date: Sep 2004 Location: CA Posts: 1,189	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. __________________ BobbyT #050110-5596 AKA bob@pelicanparts.com 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

11-17-2008, 07:22 PM	#9
BobbyT Addict Lifetime Rennlist Member Join Date: Sep 2004 Location: CA Posts: 1,189	Is there a way to disable the SAI pump temporarily to see if the noise goes away? __________________ BobbyT #050110-5596 AKA bob@pelicanparts.com 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

11-17-2008, 07:26 PM	#11
cabrio993 Addict Rennlist Member Join Date: Feb 2005 Location: Johns Creek, GA Posts: 4,671	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. __________________ RLM#: 050220-5787 96 993 Cabriolet - H&R Springs, Bilstein HD shocks, Rennline Strut brace, 18" Turbo wheels, Hardwire Passport 8500/remote, Alu bezel rings, Raid 340mm Daytona steering wheel, Alu/Carbon Brake lever, Alu/Leather shifter, RSR exahust, Big Oval tips, Short Shift and more to come... 13 Audi S4 Prestige 6MT Sport Diff. 07 Lexus RX-350 - "Mom Mobile"

11-17-2008, 08:33 PM	#12
Boeing 717 Addict Rennlist Member Join Date: Oct 2005 Location: Atlanta Posts: 6,363	My Car does it too but i just put brand new belts in. I figure they just need to be tensioned some. __________________ JERRY 2007 997 Turbo 2005 955 Cayenne Previously owned 1991 964 Turbo 1987 944

11-18-2008, 01:43 AM	#13
BobbyT Addict Lifetime Rennlist Member Join Date: Sep 2004 Location: CA Posts: 1,189	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. __________________ BobbyT #050110-5596 AKA bob@pelicanparts.com 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

11-18-2008, 09:26 AM	#14
wolfgang1 Addict Rennlist Member Join Date: Jul 2004 Location: Houston Posts: 128	I had that problem too... for me it was the fan roller belt. http://p-car.com/diy/roller/

11-18-2008, 11:54 AM	#15
BobbyT Addict Lifetime Rennlist Member Join Date: Sep 2004 Location: CA Posts: 1,189	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... __________________ BobbyT #050110-5596 AKA bob@pelicanparts.com 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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