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Whine in engine

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plkelly
New User

Sep 11, 2011, 12:49 PM

Post #1 of 8 (3114 views)
Whine in engine Sign In

I havean 04 Trailblazer w/4.2. I have an engine whine that sounds electrical. I am a retired auto mechanics teacher, current ASE certified. I repalced the alternator because it definately sounded like it was coming from the alternator. I used a stethescope to listen to the whole engine. The whine increases with acceleration. It has a new belt and battery. Fan clutch engagement does not affect the noise. Water pump seems to be tight and its not overheating or throwing any codes. As I said, it sounds 100 % electrical. Car runs fine. Since it has the serpantine belt, I can not remove belts too eliminate the noise. The PS pump is quiet. I couldn't find any TSBs on it. Any ideas?


(This post was edited by plkelly on Sep 11, 2011, 1:12 PM)


Discretesignals
Ultimate Carjunky / Moderator
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Sep 11, 2011, 12:51 PM

Post #2 of 8 (3112 views)
Re: Whine in engine Sign In

If you unplug the alternator's electrical connector, does the whine go away?

Since you are a retired automotive instructor are you testing us?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Sep 11, 2011, 12:58 PM)


plkelly
New User

Sep 11, 2011, 1:11 PM

Post #3 of 8 (3093 views)
Re: Whine in engine Sign In

I am not testing you. I have never had a problem like this that seems to defy all logic. The noise does not go away when unplugging the alternator. Any other ideas?


re-tired
Veteran / Moderator
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Sep 11, 2011, 4:23 PM

Post #4 of 8 (3067 views)
Re: Whine in engine Sign In

Try unplugging the electric air pump before starting engine.,


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Hammer Time
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Sep 11, 2011, 4:24 PM

Post #5 of 8 (3067 views)
Re: Whine in engine Sign In

You should be able to remove the belt at least long enough to see if the noise is still there or not so you will know for sure if it is a belt driven component or not. It's probably an idler pulley, tensioner pulley or something like that.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Discretesignals
Ultimate Carjunky / Moderator
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Sep 11, 2011, 4:32 PM

Post #6 of 8 (3062 views)
Re: Whine in engine Sign In

I agree with HT. You should be able to remove the drive belt. There were a couple of hits on IATN for the fan clutch making a whining noise. They had a TSB on the fan clutch wiring harness chaffing (TSB 05-06-02-012B).

Did you scan the PCM for trouble codes? If so, what is being stored? If you have a scan tool with bidirectional control, you can command the fan clutch to check its operation and to see if the noise changes.

I thought about the AIR pump too, till he/she stated that the whine noise increases with engine rpm.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Sep 11, 2011, 4:38 PM)


plkelly
New User

Sep 11, 2011, 6:15 PM

Post #7 of 8 (3048 views)
Re: Whine in engine Sign In

Worth a try.


plkelly
New User

Sep 11, 2011, 6:18 PM

Post #8 of 8 (3046 views)
Re: Whine in engine Sign In

No PCM codes. Don't have a sophisticated scanner. I might borrow one. Thanks






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