What is causing my car to make a whirring/pulsing noise?

Queenie Ruthers: A broken belt in a tire is the most likely culprit to me, especially if the car has a pronounced sideways movement with each rotation at low speed. You say you moved your spare tire around to each active position on your car, but what if you have more than one bad tire? Other things you could have checked are the "u-joints" for your driveshaft. If your car makes more noise when turning on direction versus the other, then I believe its wheel bearings (which you say you've had one replaced - I like to replace both bearings on the same axle at one time unless the vehicle has been in a collision and the vehicle has low miles on it), or your differential (in your rear axle). A ball joint should not make the noise you describe, as it is not a rotating part - it allows your front suspension to move vertically, and permits the steering wheels to turn left or right (but I would replace them too if they were worn).In either case, the only potential problems tha! t present a safety hazard are tires and the front driveshaft u-joint. The ball joint would also be unsafe if it failed, but it would cause the insides of your front tires to wear out quickly long before it failed. The other problems would merely leave you stranded....Show more