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alsevans
Novice
May 29, 2010, 2:25 PM
Post #1 of 5
(7759 views)
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high pitched whine
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I have a 2004 GMC 4.2 liter Envoy with 60,000 miles on it. Any time I start it up there is a high pitched whine, like a bearing going bad, coming from under the hood which lasts about 20 seconds then slows and stops like an electric motor with a bad bearing has been shut off. If I turn off the engine right away, the whine starts to slow but the engine stops before the whine stops. I can not isolate the noise with a hose in my ear but, standing in front, it seems to come from the left side rear of the engine, and is not the alternator, power steering, water pump or fan. I can't hear it as well if I'm in the car with the windows closed.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
May 30, 2010, 8:35 AM
Post #2 of 5
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Re: high pitched whine
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Hmmm? This can do this with engine off and slowly go away? That suggests a fan for cooling system or radiator or perhaps sound travels the blower motor which would be fast to be quiet usually or change tone with speed requested,
T
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alsevans
Novice
May 31, 2010, 9:18 AM
Post #3 of 5
(7745 views)
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Re: high pitched whine
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The bearing noise I'm hearing in my 2004 4.2 liter GMC Envoy is coming from the left rear of the engine where the starter would normally be. It is only heard after the starter has been engaged and the engine has started. The whine lasts about 20 seconds until that motor slows down and stops. I wasn't aware that the starter continued to spin that long after the engine has started but if that spin time is normal, I've found my problem.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
May 31, 2010, 9:46 AM
Post #4 of 5
(7742 views)
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Re: high pitched whine
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Starter itself should be off when off pretty instantly. If this sounds like it's partially still "meshing" on ring gear/flywheel there's action to take soon.
Will it do it again and again if restarted or just the once?
Noises are tough especially from inside as I can guess you aren't out under hood listening but could with a helper.
A high pitched belt squeal could be a loose belt usually the alternator quickly trying to put back to battery what starter just took out. Starter is by far the biggest and fastest drain on the battery so alternator works hard right away for a short time.
Noises can absolutely fool you as to where they are from and high pitched ones can be worse to isolate.
Not sure on this engine - someone may chime in. Some GM engines have problems with flex plate that is holding the "ring gear/flywheel" at least reported here but I haven't had the trouble with any yet,
T
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fescom
Novice
Jul 10, 2010, 9:51 PM
Post #5 of 5
(7674 views)
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Re: high pitched whine
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HIGH PITCHED NOISES ARE DIRECTIONAL AND LOW SOUNDS ARE NON-DIRECTIONAL, EVER TRY TO FIND OUT WHERE A SUBWOOFER IS COMING FROM? SO A HIGH PITCH IS DETECTABLE WITH A PIECE OF VACUUM HOSE TO YOUR EAR AND THE OTHER END
USED TO LOCATE OR PROBE FOR THE SQUEAL, OR YOU CAN TRY THE STETHESCOPE METHOD ALSO.
MY 2 CENTS
GOOD LUCK
OH CRAP, SORRY FOR THE CAPS
(This post was edited by fescom on Jul 10, 2010, 9:54 PM)
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