tlpvt

Hi all,
I hit a curb recently - the car slid on ice @~20mph or so in a parking lot; the f&%$ng curb broke off a chunk of the front right wheel lip but the tire held on and I drove home ok without any noticeable alignment issues.
next day took the car to a dealer - they replaced oem 18" wheel, checked alignment (it was not significantly out of specs), did not find any bent parts in the suspension, checked the hub/bearing, the tire did not have any noticeable uneven wear so they tell me everything is good.
then in a couple days I start noticing a weird recurring/periodic humming noise (~1sec intervals), like someting is grinding ...on/off...on/off... the noise is coming from the front ONLY between 40-45mph; if the speed is lower or higher than that - can't hear any noise. it is as if something is resonating only at certain speed.
the car drives ok oterwise, no pulling to the side, but the noise continues, again ONLY at 40-45mph.
Went back to the dealer but they coudn't find anything whong. they switched front and back wheels to rule out any wheel/tire defects but to no avail.

any suggestions/ideas?
this humming is driving me nuts :-(

Nuke

Did you hit the curb head-on or at an angle? You may have hit such that you overloaded a wheel bearing. Since the sound is vehicle speed related plus where it's coming from and not engine speed related you can rule out almost everything BUT front end. A harmonic in a specific portion of a speed range is indicative of a bearing issue IMO.

157dB

Jack up the suspected wheel thats been replaced and rotate it.
Any noise? Is it running true?
Grab it top and bottom and check the bearing play.
Grad it side to side to check tie rods and such.
Visually inspect all front end components for
damage yourself.
Do a lock to lock turn while someone watches from
the front of the vehicle. Any unusual noises there?
Do you have ABS?
Those have been known to produse noises like you
describe when something gets inbetween the exciter
ring and the pick-up.
I would go back to stealership and reproduce the
noise for the service manager and complain about
the partial fix.

siggyfreud

It's pretty rare for a wheel bearing to take a hit like that and be fine. Severe tire imbalance can cause the noise, but more than likely its the bearing.

tlpvt

at an angle, so just the right wheel was hit.

jwog666

+1 its the wheel bearing, swerve slightly side to side while its making the noise, if it changes as the weight transfers side to side thats telltale bearing noise.

tlpvt

it turns out the noise disappears whe turning left.
so it's the bearing, huh...?

jwog666

yep, happens all the time

bigblue95z

Yes, very true. What I deal with every day at work. We've got some very powerful electric motors and we check them at all speeds for vibration evaluation. Sometimes I feel jealous that the electric motor I'm working on is beefier than my car's engine. lol

tlpvt

so the dealer says that bearing replacement is NOT covered by the 5yr powertrain warranty because I hit the wheel. is it doable to replace it DIY and is the alignment check/adjust necessary after the new bearing is in?
one more thing: what kind of grease to use?
thanks!