Car Repair Help by Professional Mechanics
Troubleshooting
/ Whirring
Grumble
Sound
Whirring or Grumble Sound at Front/Rear
Some road noise is normal but excessive road noise like a
grumble or a whirring noise from the front or rear of the car can be a sign of a
failing wheel bearing or tire wear condition (cupping, feathering). An axle
bearing can fail from overloading or excessive mileage, while the tire condition
is caused by improper alignment, worn out struts, shocks and or tire imbalance.
To identify these conditions we have listed below some of the more common
solutions to various problems.
Troubleshooting Procedure
A. Check the Tire Wear Pattern.
A tire with a scalloped pattern on the tire will cause a whirring sound at speeds
over about 45 MPH. This tire condition is caused by a combination of worn struts or
shocks and or tire imbalance. If a tire is not being controlled evenly the tire
will vibrate causing the tread to contact the ground inconsistently. This
inconsistent contact with the road causes the tires tread to wear unevenly.
(Cupping, tire example on the right). To check for this condition, take your
hand and pass it over the tire tread, it should be smooth. If high and low
points exist the tire is cupped and needs to be rotated or replaced depending on
the severity of the cupping condition, and the suspension repair accordingly. 
Tire Wear Patterns
B. Inspect Axle Bearings
As a front or rear axle bearing fails it will create a grumble or whirring
sound. To check for this condition the axle bearing must be removed and
disassembled to inspect for metal shavings inside the bearing. This is a sign
the bearing has failed and needs replacement. A quick way of checking for a
failed axle bearing is to safely suspend the vehicle so there is no weight on
the tire. Grab a hold of the tire with both hands and shake it back and forth
(top to bottom). If the wheel seems loose further
inspection is required. This method does not always work because sometimes axle
bearings can remain tight even though they have
failed, but this method will detect most
failures. In the event of an axle bearing failure it is highly advised to
replace the bearing immediately to avoid catastrophic failure. Depending on the
type of bearing you are servicing a special puller tool maybe required.
C. Inspect Rear Axle Pinion Bearing. The gear that drives the ring gear is called a pinion gear. The pinion gear
is supported by a primary and secondary bearing. When the pinion bearing fails it
will cause a rumble and whirring sound in the main rear carrier. To check for this
condition the pinion bearing must be removed and disassembled to inspect for metal
shavings inside the bearing. This is a sign the bearing has failed and needs replacement.
A quick way of checking for a failed bearing or pinion bearing that could be failing
is to grab a hold of the drive shaft near the rear driver with both hands and shake
it back and forth. If the shaft seems loose further inspection is required. Disassemble
to inspect bearings and replace as needed. (Note: a press is needed to replace
the pinion
bearing)
Pinion Gear and Bearing
D. Check Main Differential
Gears. The main differential gears transfer power that is delivered from the
transmission to the wheels. These differential gears can become misaligned
because of a failed carrier or pinion bearing and they will disintegrate and fail. While this
condition is occurring it will make a whirring or grumbling sound. The only way
to confirm this condition is to disassemble and inspect the bearings and bearing
races. If you remove the oil fill drain plug and remove a small sample of oil
from the carrier, hold it up to the light and inspect for small metal particles.
If metal partials are detected further repair is required.
Failed Ring Gear Pattern
For exact specific repair procedures for any of the steps above visit our
online repair
manual page.
Troubleshooting
/ Whirring
Grumble
Sound
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