2005 Chevy Tahoe Whining Noise at low rpm

2005 CHEVROLET TAHOE
67,000 MILES • V8 • 2WD • AUTOMATIC
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KGRACE35
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Just bought a used 2005 Tahoe. Truck seems to run good except that I notice a whining noise heard when in the drivers seat at low rpm after the truck is warm. It seems to occur at about 1200 RPM and it kinda sounds like a trumpet player playing a dull single note. Happens in any gear - when at about 1200 RPM and the engine is warm. Kinda sounds like it coming from the left front of the engine. Also hear a rattle / clicking sounds from the same area periodically.

Any ideas on what this could be and how to pinpoint/repair?

Thanks.
Jan 10, 2010 at 2:31 AM
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PEAR69
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There are several things it could be. Release tension on the serpentine belt and turn all engine pullys by hand. Check the A/C Compressor, make sure it turn freely, but pay close attention to the idler and tension pullys...
Jan 10, 2010 at 3:18 AM
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KGRACE35
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Okay - will do. Will let the forum know the results.

Thanks again.
Jan 10, 2010 at 3:47 AM
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KGRACE35
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I removed the primary serpentine belt and turned the pulleys by hand. All moved freely without making noise. The power steer pully has some resistance, but I would think this would be normal since it is turning a pump.

Any other ideas on things to check?

Thanks
Jan 18, 2010 at 1:24 PM
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PEAR69
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Put the belt back on and start the engine. Then turn on the A/C. See if the sound changes when the compressor kicks in..
With the engine running - very carefully check the powersteering fluid for bubbles (you'll probably need a falshlight for this). If bubbles are present, then the pump may be leaking. Some resistance is normal - but bubbles are not.
With the belt off - check the water pump pully for side to side and up and down movement. There should be none..If there is change the pump.
Jan 18, 2010 at 6:15 PM
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KGRACE35
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I'll check these things and update the forum with my findings.

Thanks.
Jan 18, 2010 at 6:18 PM
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KGRACE35
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the ac pully was driven by a second belt. Looked like this belt wrapped around the crank and a tensioner pully. Should I remove this belt and check these pulley's as well?

Thanks
Jan 18, 2010 at 6:20 PM