2001 Toyota 4Runner Loud Hum at 60+ MPH

2001 TOYOTA 4RUNNER
150,000 MILES • 6 CYL • 2WD • AUTOMATIC
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PLSCHRADER
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This sound started suddenly. Went away then came back. There does not seem to be vibration just a loud hum. It is there on acceleration and stops when I take my foot off the gas. The differential was just replaced and the noise did not stop. I have never replaced ujoints.
Jul 15, 2008 at 8:44 AM
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DOCFIXIT
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Let's do a test to help locate source of hum.
Start out in first manually shift up to drive
Is noise louder in some gears ? it never goes away unless you lift off the throttle?
Let me know
Jul 15, 2008 at 9:00 AM
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PLSCHRADER
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It only makes the hum at 60+ mph.
Jul 15, 2008 at 9:06 AM
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DOCFIXIT
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Could you like tell me what area of the vehicle the hum seems to come from?
Jul 15, 2008 at 9:09 AM
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PLSCHRADER
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It seems to be from the front. Some people try to blame it on the tires but that doesn't make sense to me if the noise stops when I take my foot off the accelerator. The thought of taking it to the dealership scares me. I have a good independent mechanic.
Jul 15, 2008 at 9:18 AM
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DOCFIXIT
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It does sound drive train related I'm like you tires not it.O.K. We need to start ruling out some possible causes. At 60+ humming away shift to neutral while coasting give it some throttle hum or no hum.
Let me know
Also while it is humming slightly turn wheel left and right any change in hum? and does hum get louder the faster you go?
Jul 15, 2008 at 9:28 AM
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PLSCHRADER
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It does sound drive train related I'm like you tires not it.O.K. We need to start ruling out some possible causes. At 60+ humming away shift to neutral while coasting give it some throttle hum or no hum.
Let me know
When I am coasting and give it some throttle there is no hum.

Also while it is humming slightly turn wheel left and right any change in hum?
No change

and does hum get louder the faster you go?
It is constant. It does not seem to get louder at louder speeds.

Crap. I am going to semi-retire in 6 months and me and this car wanted to hit the road. I am a big believer in preventive maintanence
.

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Jul 15, 2008 at 9:47 AM
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KHLOW2008
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Hi plschrader,

The symptom described is similar to U-joints getting stiff due to lack of lubricants.

Removing the propeller shafts would allow you to test if the joints are bad.
Aug 17, 2008 at 6:12 AM