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Join Date: Jul 2007
Posts: 204
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Strange Engine Noise
OK, I know noise diagnosis is notoriously difficult without the actual sound. I sometimes get a strange low frequency humming buzzing, noise from the engine ('91 964 C2, Tiptronic) that is very rpm depended. It is most pronounced at idle and tends to go away at around 3000 rpm. It is there when the car is stationary, i.e not wheels, clutch, etc. dependent. It sounds like a fan, a pump, but then again... Any thoughts? I know it is vague. Thanks!
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'91 C2 Targa |
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11-08-2008, 12:08 PM
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Is it more mechanical sounding our electrical sounding?
I bet the noise is not going away, you just can't hear it at the higher RPMs Exhaust/cat shielding? Power Steering pump?
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Don Plumley M235i memories: 87 911, 96 993, 13 Cayenne |
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11-09-2008, 08:33 AM
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More mechnical - almost like a fan running at lower speed. I did not think of the power steering pump. From the driver's seat it sound like the noise is coming from over my shoulder, i.e rear right... Thanks
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'91 C2 Targa |
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11-10-2008, 11:45 AM
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Join Date: Nov 2000
Location: Dallas
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Alternator bearing?
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Buck '88 Coupe, '87 Cab, '88 535i sold, '19 GLC 300 DD Warren Hall, gone but not forgotten |
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11-10-2008, 12:10 PM
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That was my first thought but apparently the alternator and bearing were replaced 2 years ago.... The search continues.
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'91 C2 Targa |
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11-13-2008, 06:07 AM
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Start removing the belts one at a time. That's the only way you can isolate the source whether it's coming from the A/C, fan or alternator.
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1993 964 C2 still makes me smile Retired and work as needed as a pain in the **s. |
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11-13-2008, 08:20 AM
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1987 Porsche Carrera 3.2 
911
