Drivetrain/Brakes/Tires - Buzzing Noise From Front End
NO: 77-19DATE: 9-28-2007
MODEL:
S40 (2004.5-)
V50 (2005-)
C70 (2006-)
C30 (2007-)
SUBJECT:
Diagnosis/repair of buzzing noise from front while driving
REFERENCE:
VIDA, VRC2, STB # 002
Description
There may be cases when a buzzing noise can be heard from the front of the car during normal driving. The noise may become louder as the vehicle speed increases. Sometimes the noise can be more pronounced in a curve or when driving above a certain speed.
Diagnosis
There is no substitute for obtaining a complete and accurate understanding of the customer's symptoms. VRC2 contains a wealth of best practices and resources on how to manage the customer service process. (Find these links under > Operations > CSI Improvement Tools.) Briefly, a technician should be certain that he/she possesses thorough knowledge of the customer's symptoms before beginning a repair attempt. In many cases, especially cases involving noise or an intermittent symptom, this should include a road test with the customer to verify the symptom.
Note!
Use the 'Noise - Vibration Questionnaire' which is shown above.
Service
Buzzing type noises from the front of the vehicle may have the following root causes:
1. Worn tires, especially tires with uneven wear.
2. Driveshaft bearing noise.
3. Brake dust shield in contact with brake disc.
4. Worn or damaged front wheel hub.
Note!
The above list is not intended to be an exhaustive list of all possible sources of buzzing noises. We strongly recommend the use of a 'Chassis Ear' tool kit to determine the source of the noise (see Special Tool Bulletin # 002, "Workshop Equipment")
To fault trace the noise, first road test the car based on the customer's description of the symptoms. Determine if the noise changes at different road and engine speeds, turning left/right, etc.
With the engine off, parking brake set, and the transmission in neutral, raise the car on a hoist so that the tires hang free. Rotate each front tire by hand and listen for noises.
1. If the noise is NOT present with the car on the hoist while turning the wheel:
a. Check tires for wear; check and record tire tread depth.
b. If tires are still good, swap tires left/right and road test again to hear if the noise follows the tire.
c. If the noise follows the tire, rotate the tires back to their original positions, and replace the noisy tire after approval from the customer or tire manufacturer as appropriate.
d. If the tires are worn to the point of replacement, replace the tires after approval from the customer.
Note!
There may be noise from the front tires if they have been rotated from the rear and are unevenly worn.
2. If the noise IS present with the car on the hoist while turning the wheel:
a. Check if the brake dust shield has any contact with the brake disc. Correct as necessary.
b. Use the Chassis Ear tool to determine if the noise comes from the driveshaft bearing or from the wheel bearing.
^ If the noise comes from the driveshaft bearing, replace the driveshaft.
^ If the noise comes from the wheel bearing, replace the wheel hub.
Note!
Replace the driveshaft or wheel hub only on the side which is confirmed to be noisy.