I have a 1999 Chevy Geo Prizm a.k.a. Toyota Corolla. I am new to car ownership and don’t know much about maintenance yet, so I am worried about getting fleeced when I take my car in for repairs.
Recently, the back right wheel has started making a soft “wumm wumm wumm” noise when the car is in motion. The faster I drive, the more the noise speeds up, so it seems like something is coming loose or out of alignment. I’ve driven over a fair number of potholes in the last couple of months, and while I don’t remember any particularly gnarly ones, I imagine that’s what has caused the problem.
Any guesses as to what might be going wrong, how dire it is, and what I should expect to hear from the mechanic when I take it in?
A bad wheel bearing
or
A tire with an internal defect
Either of these issues could be the result of driving on bad roads, and–more importantly–both possibilities are safety issues, so you need to get this attended to promptly before an accident takes place.
My advice is to AVOID all chain operations like Midas, Meineke, Monro, Sears, Pep Boys or (shudder…) AAMCO, and to go to a local independent shop that has a good reputation. Ask friends, neighbors, relatives, and co-workers for recommendations, or use the Mechanics Files link at the top of this page for recommended mechanics in your zip code.
Let me add to @VDC’s good suggestions, the rear brake drum. I love these cars but they are susceotable to brake noise, front and rear.
A balky parking brake cable and an irregular drag in a slightly out of round drum could cause it too. A Worn or dragging shoe as well can be looked at. Regardless, get it fixed.
They are great cars when they don’t rust. I am jealous I still don’t have mine. My suggestion (parking brake part) may be easier to fix ( lube the cable and linkage and spring) @VDC’s perhaps the real cause is more expensive.
From the driver’s seat , what seems like the right rear may not be. Sound radiates through the body parts and can be deceiving.
Get the car up on a shop hoist for diagnosis.
Start spinning wheels and listening to see if it’s a bearing or brakes.
LOOK at the tire tread as you spin it to see if it varys as it spins to see if it’s the tire.
A pot hole can break the tire’s internals and it could be just the tire.
A rear wheel bearing assembly at Auto zone is about 60 bucks.
Afraid of getting fleeced ?
Who is your regular local shop ?
That’s all that’s needed for this.
Do they offer free diagnosis ?
“what seems like the right rear may not be. Sound radiates through the body parts and can be deceiving.”
Ken makes a good point.
Unitized body/chassis structures can “telegraph” noises so that they seem to be coming from an area other than where they are actually originating, so, while I still think that the problem is most likely to be a bad bearing or a defective tire in the right rear, it is also possible that the noise is emanating from a different location.
A lot of good points here. Allow me to add a bit of personal experience.
Toyota, along with others, has gone to ball bearings for the wheels for the lower rolling resistance. Ball bearings do not stand up to impact as well as the roller bearings that manufacturers used to use. The noise you describe is classic for wheel bearing s that have seen one too many potholes.
I own a 2005 Scion (Toyota) with 209,000 miles, some of them hitting potholes. At this point I’ve changed out my front bearings (about two years ago after banging a pothole and definitely damaging one) and my rear bearings (the week before last, because I too got tired of that throbbing sound). My car now runs as quiet as it did when it was brand new.
The front bearing clearly was damaged.
The rear bearings could not be verified as damaged/worn by mechanics. But changing the rear bearings definitely did away with the throbbing. The mechanics that couldn’t verify the throbbing are good friends, highly experienced and certified, that teach a degree-bearing automotive technology program at the college I retired from. They have no interest in not being honest, and being friends and of high integrity, they definitely were. This type and amount of wear simply could not be verified on the lift, and was suttle enough to not be any different from normal tire wear noise. In a normal situation, if I didn’t know them and they didn’t know me well, if I’d have brought the car into them they would have been in honest to simply tell me they could not verify a problem and declined to change the bearings.
I wrote this because
wheel bearing damage from one too many potholes is not uncommon
if mechanics tell you they cannot verify the problem they’re probably being honest.
if you have them change out the bearings anyway, it’ll be expensive, and it might NOT solve the problem. Thinks like tire wear also cause these sounds and should be eliminated as possible causes first.
What I’d suggest is to have it looked at and if the shop can’t verify a source of the sound, wait until it’s time to change the tires anyway and see if the throbbing continues. If it’s gone, it was the tires. If it’s not, you can decide whether to pay for new bearings or accept the throbbing. A level of wear that isn’t verifiable on the lift is not a bearing on the verge of failing, it’s simply wear. A bearing on the verge of failure would be verifiable.
Thank you all VERY much for your thorough and helpful advice! It’s a relief to know some possible causes and some potential courses of action I can take based on what the mechanic says.