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Discussion Starter #1
Suddenly there one day, not a gradual build-up. 150,000 miles. Well cared for.

Sounds like a wheel bearing but it doesn't change with the swerve test. I'm told rear bearings "never" fail on 9-5s.....

If I had to put money on it I'd say it was front end, but I've been fooled with that before (Civic rear bearing - I even changed the discs/pads!)

Its first audible about 20 mph, peaks at 40, then another peak at 60. But its always there, a distant low frequency drone, moan or hum.

Its road speed related, not rpm, and doesn't change when I press clutch or select neutral.

Accelerating in 2nd there's a slight "wow wow wow wow" like props out of synch in a small twin engine aircraft (which will mean something to any pilots amongst you). Of course the frequency of the "wow wow" increases with car speed.

In 4th gear even at constant speed, there's a similar slight "wow wow wow wow", lower freq. than in 2nd. Lift off the gas, still in gear, - this stops. Can't get this in 3rd or 5th at the same speed. Its like two components' resonances are interfering, close to but not quite in synch.

I don't think I can detect any additional vibration through steering wheel, gear knob, seat, pedals etc.

I've swapped rear tyres to front and v.v., which are all in good condition with no rear inner edge damage - no difference to the sound.

Over 300 miles it hasn't got any worse.

Last week my mechanic agreed to drive it but we're not sure thats a good idea any more. Might have to resurrect the other car from hibernation.

Any ideas out there would be much appreciated.
 

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I wouldn’t discount the wheel bearing. They can make different noises and swerve test may not be conclusive.

Just replaced the right side OE bearing on my daughter’s 9-3 with 160K. Thought it was tire, axle, carrier bearing. Spinning wheel or prying it showed no sound or play but when I removed it, it was obvious that it was shot. Fortunately, 9-5 and NG9-3 bearings are easily replaced (bolted in, not pressed) and aren’t expensive.
 

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Discussion Starter #3
Thanks Steve, I'm trying to keep an open mind!

Would the sound come on suddenly though? I've limited experience, but the Honda's grew over a couple of years.
 

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Probably not suddenly - but who knows?

I drove the car a couple of days before without hearing it - but admittedly, the radio might have been on at the time. My daughter then told me she started hearing a noise. It got louder over next week or 150 or so miles.
 

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I know, different car, but I think you know something about them too Doug, I had a pretty sudden wheel bearing failure on my 9000 just last week. I feel like i heard something say Thursday, enough t try to listen friday morning but nothing satisfactory, and then Friday night I had a whump whump flat tire sounding wheel bearing noise, growing louder and louder over a 20 minute drive. Did not change during swerve test, but as soon as I rocked it 12 and 6 it was clear as day..... Now long story longer, I replaced it with a new SKF hub/bearing and on the test drive it was terrible out of the box, extreme loud growling, no swerve test difference. AND it did not rock at all 12 to 6 or 3 to 9.... But when i spun the wheel (tire on) by hand and grabbed the coil spring, clearly you could feel the bearings rumbling...

Just swapped it with a 40 dollar API hub bearing.... bet I will be doing this again in about a years time. Very frustrated with the out of box failure.

but swerve test not conclusive, and even rocking tire/wheel not conclusive in these two failures... As well as sudden (day or two) failure of the first bearing. Try grabbing the coil and spinning the wheel as fast as you can get it going.... might help verify? good luck.
 

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Discussion Starter #6
Thanks andtheHawks. I hadn't heard of the hold-the-coil-spring method, which I will try.

Appreciate the input.
 

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It cant hurt. though of course jacking car up and down and up again can be a hassle. Do try to spin wheel on opposite side as a comparison to get a control.. A bad bearing definitely feels noticeable in the coil compared to a good bearing (assuming you do have a bearing issue and not more than one....). its not night and day comparison, but pretty close- truth be told.
 
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