Rear noise at 40-60MPH

Tiny
BRIANJXNES
  • MEMBER
  • 2006 TOYOTA 4RUNNER
  • 4.0L
  • V6
  • 4WD
  • AUTOMATIC
  • 156,000 MILES
When cruising at 40MPH, I hear a howling noise in the rear. I turn the wheel left and right and the noise is still there. I let off the gas completely, the noise is still there. I put the car in neutral and let it coast at 40MPH the noise is still there. What do you think it could be?
Wednesday, October 27th, 2021 AT 7:16 PM

12 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Good morning,

It sounds like a bearing failure in the differential itself. You have axle bearings, pinion bearings, and carrier bearings. I attached a picture for you to view.

https://www.2carpros.com/articles/how-a-differential-works

https://www.2carpros.com/articles/differential-service

This could be caused by low oil levels or not changing the oil regularly.

In most cases, it is cheaper to replace the entire differential assembly with a used unit instead of rebuilding the old one. It can get very pricey to rebuild the assembly.

Roy
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Thursday, October 28th, 2021 AT 3:23 AM
Tiny
BRIANJXNES
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Thanks for the quick response! So, should I begin with doing a differential fluid change and see what that does first? Or does the howling sound indicate that the differential assembly is pretty much done?
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Thursday, October 28th, 2021 AT 5:04 AM
Tiny
ASEMASTER6371
  • MECHANIC
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Changing the oil will not do anything about the noise. The damage has already been done.

I would start looking for a differential assembly at a junkyard. There should be a tag on the cover of the rear of the car. You will need that tag with the numbers to match up the correct part.

Roy
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Thursday, October 28th, 2021 AT 5:50 AM
Tiny
BRIANJXNES
  • MEMBER
  • 7 POSTS
What is the approximate repair cost for this type of job?
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Thursday, October 28th, 2021 AT 10:46 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
The differential assembly is around $500.00.

The labor is 8 hours at $150.00 per hour.

$1,500.00 to $2, 00.000 for the job.

Roy
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Thursday, October 28th, 2021 AT 12:50 PM
Tiny
BRIANJXNES
  • MEMBER
  • 7 POSTS
Just to confirm, is it optimal to just replace only the third member (pumpkin) or are you indicating that it’s best to replace the entire rear mechanical assembly such as the axle shafts and third member all together?
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Thursday, October 28th, 2021 AT 4:05 PM
Tiny
ASEMASTER6371
  • MECHANIC
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You should also do the axle bearings as well. The pumpkin is mandatory, yes.

I would do it right.

Roy
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Friday, October 29th, 2021 AT 4:10 AM
Tiny
BRIANJXNES
  • MEMBER
  • 7 POSTS
Thank you for your help!
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Friday, October 29th, 2021 AT 5:04 AM
Tiny
ASEMASTER6371
  • MECHANIC
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You are welcome.

Always glad to help.

Roy
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Friday, October 29th, 2021 AT 5:09 AM
Tiny
ASEMASTER6371
  • MECHANIC
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Let me know if you have any other questions.

Roy
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Friday, October 29th, 2021 AT 1:12 PM
Tiny
BRIANJXNES
  • MEMBER
  • 7 POSTS
Just one more question. If I replace the entire assembly, the replacement unit would also need to have the locking differential function I’m assuming.
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Saturday, October 30th, 2021 AT 9:07 PM
Tiny
ASEMASTER6371
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Correct, in order for it to work correctly.

Roy
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Sunday, October 31st, 2021 AT 2:35 PM

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