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sprinkles08
sprinkles08, ASE Certified Technician
Category: UK Car
Satisfied Customers: 21609
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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We drive a 2000 Grand Cherokee, which we bought about a year

Customer Question

Hi,
We drive a 2000 Grand Cherokee, which we bought about a year ago. When we reach about 60 mph an ear piercing high pitched whining noise starts to appear from somewhere in the car. The moment we go over 80 mph it vanishes completely. We had the car checked by our garage, even taken the gear box appart. Everything is absolutely fine, but the deafining noise stays with us. Any idea what could cause it?
Submitted: 27 days ago.
Category: UK Car
Expert:  sprinkles08 replied 26 days ago.

Hello and welcome to JustAnswer!

If it's a speed dependent whine noise then I would first suspect gear noise from the rear differential. Incorrect contact pattern due to worn ring and pinion gears will cause a throttle sensitive whine that will often happen in a certain speed range.

Is the noise throttle sensitive?

Customer: replied 26 days ago.
Hi,
Thanks for you reply.
To answer your question: No, the noise is not throttle sensitive. It just occurs between about 60 and 80 mph, eben when you go downhill and let the car just roll.
Any other idea where we could look?
Peter
Expert:  sprinkles08 replied 26 days ago.
Does it come from the rear of the vehicle?
Customer: replied 26 days ago.
It seems to travel through the whole car. If you sit in the drivers's seat it seems to come from the right hand side, in the passenger seat from the left and in the back from somewhere in the back. That's exactly what makes it so hard to detect.
Expert:  sprinkles08 replied 26 days ago.

Does it change in pitch or come and go if you swerve?

Customer: replied 26 days ago.
It is absolutely consistent between 60 and 80 mph. We take the car a lot to Europe/Germany where we can drive most of the time on the motorway with over 80 mph. The noise immediately stops when we reach 80 or go below about 60, swerving or not. In the beginning we thought it might be a wheel bearing, but we had them all checked and they are they are in a perfect condition.
Expert:  sprinkles08 replied 26 days ago.

If the noise changed when swerving then it would be a wheel bearing. A stethoscope can be used with the vehicle running on a hoist to determine where the noise is coming from, I believe you either have gear or bearing noise in the rear differential.

Customer: replied 25 days ago.
But why is it happening only between 60 and 80 mph and what might be causing the noise?
Expert:  sprinkles08 replied 25 days ago.
As I mentioned the noise is most likely coming from the gears or bearings in the rear differential. Gear noise usually happens in a specific speed range.

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