I have a 1995 Toyota Corolla and the front wheel (driver side) is making a grinding/humming sound when I’m driving. The sound is loudest when driving on the freeway (when going 75mph it gets up to 93 db… used a smart-phone app to detect level of noise). When driving in the city you can’t really notice the noise unless you are going faster than 30 mph. I took it to my mechanic and he can’t find the problem. Here is what he has done:
He checked the front Axles (no play and no tear in the boot).
Checked the bearing and no play
Brakes were bad so he replaced the pads (nothing).
Moved the front tires to back (sound is still coming from the front)
Changed the struts (they were worn, still same sound).
He took the car off the ground and “drove it” I did not hear the sound then (but then the tires were not spinning very fast).
He said the mounts look OK.
The noise seems the same level if I go straight or if I’m turning. A few weeks ago the noise was present but not as loud as today (I took the car on a road trip and it seems that it got loader after that).
My mechanic says it *could* be the beginning of a tranny problem … but if I drive straight and then put the gear in neutral I still hear the noise (not even a change in noise level). Do you have any idea what’s going on?
Symptoms indicates a bad wheel bearing. Front wheel bearing noises are not that easy to detect especially when it is only beginning to fail. Remove the CV shaft and spinning the wheel would allow you to test the bearing more accurately.
August, 14, 2011 AT 8:27 PM
Hi guys. Let me turn your attention in a different direction. Any mechanic with only a few months experience has heard a noisy wheel bearing. Based on your dandy description, that's the first thing he should have headed for, not things that don't make noise on the highway like struts and brake pads. Standing next to the car and listening isn't going to work because there's no vehicle weight on the bearings. They will rarely have play in them either when they first become noisy. I don't say this often or lightly, but I have to wonder about your mechanic's competence, training, or experience.
You noticed the noise doesn't change when you steer to one side. That's also a useful observation. On most cars with the less expensive pressed-in bearings, if the left one is noisy, it will get quieter when you turn left and more weight shifts to the right side. That can be observed by simply changing lanes on the highway. With the more expensive but less labor-intensive bolt-on style bearings, it is real common for the noise to not change when turning. Additionally, on many cars such as the Dodge Intrepid, it can sound to everyone in the car like the noise is coming from the right wheel, and it turns out to be the left bearing that's noisy. On those cars, the only accurate way I found to identify the noisy bearing was to run the car in gear on a hoist and listen next to each one with a stethoscope. One will have a rumbling sound, but then the other one will be REAL rough sounding. That's the bad one, but you won't hear it without the stethoscope.
Another expert here says he finds them by placing his hand on the coil spring, then rotating the tires by hand. He can feel the rumbling from the bad bearing. I haven't had a chance to try that yet.
There is also a tool called a "Chassis Ear" that is useful in finding the source of a noise. It is a set of six microphones, a switch box, and head phones. You clip the microphones to suspect parts, then switch between them and listen during a test drive. By moving the microphones around, you can zero in on the source. Your mechanic gets a pass if he has never seen this tool. Many have never even heard of it.
Brother KHLow2008 is right about the wheel bearing. Just based on the description of the symptoms that's the first thing to look at.
August, 14, 2011 AT 9:25 PM
Thanks guys! I'll take it to my mechanic to do a more in-depth look at the bearrings. (Remove the CV shaft to test. And try the hand on the coil). To be fair I told my mechanic to change the all four struts because I recently changed my tires and the shop said my tires were worn unevenly and that my shocks were shot. He also he told me to take it a shop where they specialize in troubleshooting sounds as he said he does not have those tools. (But he does not have anyone to recommend in San Jose, CA).
Question if I need to change the bearings. With my car, can I just have the bearings changed ( $20 per pair) or change the entire assembly ( $100) plus labor.
August, 16, 2011 AT 7:11 AM
I found the bearing available both ways. The less expensive bearing is much more labor-intensive so it's going to cost you a lot more for labor. The bearing and new hub as an assembly came about to address that increased labor time. The part costs more but they greatly reduce the amount of time needed to do the work. Typically the person working on the car decides which way to go. I became proficient at quickly installing the less expensive bearings on Chrysler products, so by the time the complete assemblies came on the market, the added cost to the customer couldn't be justified.