V6 rear wheel(s) humming on highway

[fenixus]

huh, I thought I have finished fixing all suspenion issues with my '02 V6 (1mz-fe @ 126k miles), but it seems not yet hehe

I think this car likes my touch

so the front end seems ultimately fixed, new front wheel bearings & hubs, new Master Cylinder, new brake pads (all around), resurfaced rotors (all around), new front quick struts, wheel alignment, new caliper slide pins and bushings all around, greased with Permatex Ceramic Extreme, all done recently.

today we are on a road trip, currently in Fairfax, VA. car behaved excellent during this ~250 mile highway trip. seems it burned a little less than 3/8ths of full gas tank (avg speed 80mph until we reached Virginia, then avg speed 60mph LOL ) according to dash gauge, not bad

only problem is that both me and wife (in passenger seat) noticed humming noise coming from the rear end while driving above or around 65-70mph

I hear it in right rear wheel (while in driver seat), she hears it in left rear wheel (while in passenger seat) ... hmmmm

last time I checked rear wheels free spin it was good with parking brake shoes backed off. however after adjusting parking brake shoes I noticed a dead spot when spinning left rear wheel, so possibly there is a warped drum surface in rotor, will have to look into that too...

considering my former experience with front wheel bearings on this car I am afraid both rear wheel bearings are going out of business too

caliper are very unlikely to bind (and make that noise), as brakes are nowhere near touchy when gently pressing the brake pedal.

I know how dragging brakes feel (had stuck caliper slide pins all round and rusted out piston in MC before) and when they were dragging and I pressed on brake pedal gently, the car was almost stopping immediately at city speeds. no more like that.

so what's left? bearings ... or maybe bad tires (unknown mileage on them, but seem like plenty of thread left, Bridgestone HP550)?

as far as I remember wheel shake test was negative on rear wheels, but it was also negative on front wheels before while front wheel bearings were already gone (car was running on hubs for a few weeks in Winter).

the last observation is that car feels (again) like it was slightly slowing down when I let the foot off the gas pedal while going down the slope (highway), while it should be accelerating on its own?

It does however accelerate on its own when going down the sharp hill (foot off the gas pedal) so nothing is tragic (mind good highway MPG, but also not so good city MPG).

also there is no difference in inertial speed when going down the gentle slope no matter if transmission is in D gear (over-drive works fine, tested it) or if I shift it to Neutral (tried that too, no effect on speedo except for drop in RPM).

any ideas how and what to test are welcome

sorry for a super long post, and thanks in advance.

[fenixus]

it sounds similar to this (not my video):

You Tube

You Tube

car in video was VW Passat 2007.

EDIT:
really started thinking about getting 2 of those in close future:
http://www.rockauto.com/catalog/moreinfo.php?pk=1118338

...

[Yuko]

Have you tried gently engaging the parking brake at speed to hear any change in noise? I had a similar noise coming from the rear that varied with vehicle speed. I through it was the hubs but felt no vibration. I decided to pull the parking brake up while driving, heard a thump, and the noise stopped. Then it returned and I continued to pull the parking brake to stop it. I later removed the rear wheel, tighten up the star wheels, and the noise haven’t return. My parking brake in the rotors has a dead spot too. It's a shot in the dark but cost nothing to test.

[fenixus]

Thanks Yuko. I will try gently engaging the e-brake on highway.
I doubt it changes anything though, because noise was similar maybe a little less before I adjusted star wheels in rotors. I do have slight vibration though, but always thought it's a slightly bent rim which I keep in rear. All wheels are balanced well however.

Will be back tomorrow afternoon.

[71Corolla]

This is what wheel bearing noise sounds like in my experience. Pretty bad case this guy has

You Tube

You Tube

[Yuko]

I heard that bend wheels (even when balanced) can cause the tires to "walk" back and forth between the shoulders and cause shimming and/or slipped belts. This may cause some noise even if the tire appears to wear evenly.

On our 07 Pathfinder a while back; my mother told me that there's a "helicopter" noise from the back that increase with speed. I tried to rotate, balance, and alignment everything but the noise was still there. When the tire wore out, I just replace all four and the noise was gone. It may be the tires but that can be pricy. I would check the brakes and suspensions first.

Also, is there anything stuck underneath? I had a trash bag caught on my heat shield near the fuel tank on the highway and it flipped like crazy. I didn't know and thought something broke but at the rest stop, I found the bag and rip it off.

[fenixus]

hmmm, his noise sounds like a train
I can imagine that his bearing would do similar noise when spiinning the wheel freely. mine doesn't do such noise. but hey front bearings appeared to be good while they were done already

my noise is like in first video.

Originally Posted by 71Corolla

This is what wheel bearing noise sounds like in my experience. Pretty bad case this guy has

http://www.youtube.com/watch?v=DHevc...eature=related

[fenixus]

I think once I get home, I may need to replace one of rear wheels with a spare one at a time and see what happens.
It could be one or both of tires in the rear, they are different then fronts (Yokohama).

we are going to National Gallery of Arts in DC now, later some diner and sightseeing

be back laters.

Originally Posted by Yuko

I heard that bend wheels (even when balanced) can cause the tires to "walk" back and forth between the shoulders and cause shimming and/or slipped belts. This may cause some noise even if the tire appears to wear evenly.

On our 07 Pathfinder a while back; my mother told me that there's a "helicopter" noise from the back that increase with speed. I tried to rotate, balance, and alignment everything but the noise was still there. When the tire wore out, I just replace all four and the noise was gone. It may be the tires but that can be pricy. I would check the brakes and suspensions first.

Also, is there anything stuck underneath? I had a trash bag caught on my heat shield near the fuel tank on the highway and it flipped like crazy. I didn't know and thought something broke but at the rest stop, I found the bag and rip it off.

[fenixus]

well, paid more attention when driving car today and it seems to hold back at slower speeds a little.
something's up again (or still).

just got back from DC trip to motel in Fairfax. for now only visually checked all tires and they all are good.
funny, but it seems that there is more thread left on old Bridgestone HP550 tires in rear than on new Yokohama AVID Envigor in front. different tires, doubt the reason is in them.

noticed that Yokohama tires (560 thread wear) in front call for max 40psi pressure while rear Bridgestone (460 thread wear) call for max 51psi tire pressure.

hmmm, I pumped them up all to around 35psi in Winter (measured at cold tire), shouldn't be a problem, but to be on safe side, I will dial down on tire pressure all around to max 32psi at cold (for front tire safety).

I tried engaging e-brake while driving on highway (rear end noise), but the noise did not change, so it's not related to parking brake assembly. I may back off the star wheel 1-2 clicks though on both sides to be sure and instead I could tighten the e-brake lever in cabin.
wondering if that rotor/drum dead spot on parking brake shoe could cause the rear end noise?

also once I get home in NJ, the plan is to swap each of rear wheels with a spare one and see what happens at highway speeds.
it could be that one of rims is bent bad enough to cause it? both rear ones are slightly out of round (saw it on balancing machine at 60mph), it's balanced correctly though.
or maybe those both HP550 tires are crap and cause all the noise?

if no change on either side then it's either the disc brakes (e.g. dust boots holding back the slider pins maybe?) or it's the wheel bearings after all again...

may need to replace dust boots on all slider pins all around something I haven't done yet regarding brakes.

[pmesfun]

I know the tires on my car makes alot of noise, pos Good-for-only-a-Year in the back and Dunlops in the front. So it could be the tires.

[fenixus]

right. I remember hearing similar noise in left front wheel right after purchased the car. then that wheel (same tire) was rotated to rear, so it's possible the noise comes from the Bridgestone crap tires (they don't even sell those anymore anywhere).

calculated the MPG on 90% highway trip from NJ to VA and it seems car did 26.4 MPG, not as awesome as I thought before.... hmmm

also since middle of Winter I am running on shell 87 regular fuel ($4.12/gal in Fairfax, yikes!)

Originally Posted by pmesfun

I know the tires on my car makes alot of noise, pos Good-for-only-a-Year in the back and Dunlops in the front. So it could be the tires.

[pmesfun]

Thats odd, it should be around 27-30+with almost all highway driving.

[fenixus]

yup, that's what I was hoping for. something is holding this car back. it felt much "lighter" right after purchase last Summer in Florida (with brake pads thin as slice of cheese).

Seems I need to replace dust boots on all caliper slide pins all around to be sure there is no more trouble (I don't really feel any brake drag anymore) and take a closer look at rear wheel bearings... they might be going out slowly with not much noise or shaking or nothing actually to let know.

will know more after I swap the rear wheels with a spare one.

Originally Posted by pmesfun

Thats odd, it should be around 27-30+with almost all highway driving.

[BMR]

In my experience, a bad wheel bearing can make very little to no noise, or a very loud growling/howling noise. On my Avy, I had a bad rear that wouldn't make any noise at less than 50 MPH or so. But at 75 it made a cyclical "woo-woo-woo" noise that varied with road speed.

But I've had tires make a very similar noise too. So IMHO, both of those are primary suspects.

[fenixus]

exactly my case, silence (almost) up to 50mph and then noise comes in and gets louder with higher speed. at 90mph I feel like I had some kind of turbine in the rear it's that loud. and it's not a constant howling, it's that "woo-woo-woo" thing...

sounds like chances for having 2 more bad bearings are growing higher.

my front bearings never tested positive for being bad until I removed them either ... couldn't even spin them with 2 hands while they were mounted on hubs and in steering knuckle. you saw the pictures from later

but those were at least making some intermittent low grinding noise at very low speeds and whenever pulling to red light. still were driveable very much and perfectly silent at highway speeds (car running on hubs LOL )

Toyota bearings die silently, true Japanese

will see what happens after I swap each rear wheel with a spare one and take it for a highway run. need to eliminate the wheels (either rims or the tires) from puzzle first.

Originally Posted by BMR

In my experience, a bad wheel bearing can make very little to no noise, or a very loud growling/howling noise. On my Avy, I had a bad rear that wouldn't make any noise at less than 50 MPH or so. But at 75 it made a cyclical "woo-woo-woo" noise that varied with road speed.

But I've had tires make a very similar noise too. So IMHO, both of those are primary suspects.