2001 GMC Yukon Whine coming from wheel wells while idlingaf

Tiny
WDOCKERY
  • MEMBER
  • 2001 GMC YUKON
Noises problem
2001 GMC Yukon 70000 miles

I have recently noticed a distinctly audible, but not loud, high-pitched whine/whistle coming from the underside of my Yukon while idling, occurring after a "hard" drive. Noticed it initially this summer during an across-the-country road trip; when I stopped for lunch after a 4 hour drive, I would hear the noise. Sounds almost like a computer laptop fan (but louder and more whistle and not so airy). I later heard the same noise after driving 15 minutes across a mountain pass. After having lunch for 30 minutes, when I turn on the Yukon, the sound is gone. Any ideas? Thanks!
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Wednesday, August 12th, 2009 AT 12:27 AM

7 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
The only thing I can think of without hearing it is the fan may be running. Were you using the AC? Could it have come from the belt?
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Monday, October 5th, 2009 AT 12:09 PM
Tiny
WDOCKERY
  • MEMBER
I appreciate your reply. I should have mentioned in my original email that the noise was unrelated to whether the A/C was off or on. Regarding belts, it seemed unlikely to me, since the noise seemed to be coming from under the truck. (But I'm not a mechanic.) I haven't heard the noise much since I've returned from vacation--I don't drive the Yukon hard in the city. Based on other internet posts, I have heard people talk about the differential as a cause of high-pitched whines. I know nothing about differentials.
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Monday, October 5th, 2009 AT 2:11 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
It could be coming from a differential. Have you checked to make sure they are full of gear lube? It isn't uncommon for the axle seals to leak causing them to get low. Also, you may want to have them serviced if you haven't already. Most people neglect them, but they do a lot of work and require proper luberication.

If you need direction on checking them, let me know. Also, did you ever hear the sound when the car was stopped?
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Monday, October 5th, 2009 AT 8:31 PM
Tiny
WDOCKERY
  • MEMBER
Thanks for your email. Yes, each time I heard the noise, the Yukon was stopped, typically in a McDonald's parking lot when we stopped for a meal during our long road trip. (The noise may have been occurring while driving, but the windows were up so I wouldn't know.)
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Monday, October 5th, 2009 AT 9:43 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
If you heard it when you were stopped, it isn't coming from the differential. I want you to try something. Start the engine, open the hood, and pour a little water on the serp belt. See if the noise changes. NOTE: water may splash back at you, so protect your eyes and wear old clothes.

Let me know what happens.
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Monday, October 5th, 2009 AT 9:54 PM
Tiny
WDOCKERY
  • MEMBER
Serp belt?
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Monday, October 5th, 2009 AT 10:09 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
It is the one large belt that runs all of the accessories under the hood. For example, it runs the alternator, waterpump, power steering, AC compressor.
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Tuesday, October 6th, 2009 AT 7:50 AM

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