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Discussion Starter · #1 ·
Hello,

I've searched high and low and haven't seen any examples that are similar to what I have going on with my 2000 Outback. It has been getting louder and more obnoxious over the last month or so.
The noise starts around 40-45mph and then starts to drop off at about 55mph, then seems to start coming on again around 70-75mph but isn't as bad. Its a low frequency drone that seems to come from the back, you can feel it throughout the car and it kind of resembles a big subwoofer.

Braking makes no difference.
No change when in gear or neutral.
Not much different around corners.
Not much different over bumps.
Not much difference with temp.
Doesn't matter what the engine RPM, just wheel speeds.
The noise decreases a little when going up a hill.
Driveability is fine, its just very very annoying!

I've had the car about 10k miles, it has 80k miles, auto trans, new tires 5 months ago, new exhaust. I was going to go through the brakes tomorrow but this noise is getting bad and I have to drive 200 miles on tuesday!

Help me out!
Thanks
 

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03 H6 OBW & 06 WRX Sportwagon
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18,136 Posts
possible diveshaft carrier bearing.

Soob wheel bearings can have odd failure modes. measuring them with an infrared thermometer might help find a bad one. If a hub is 20 degrees warmer than it's opposite side mate, could be a bad bearing.
 

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Discussion Starter · #3 ·
possible diveshaft carrier bearing.
Hmm, never changed one of those before. I'll check it out in a few minutes, along with the wheel bearings and maybe the U-joint.
Any other things I should be looking at? This is my first AWD car so I'm sure its different from what I'm used to. Wheel bearings and U-joints are usually pretty straight forward, hopefully they are in outbacks??
 

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Discussion Starter · #4 ·
So I jacked it up and noticed on the passenger side the sway bar popped off the link, I couldn't imagine this would cause much noise? I looked at what may be the carrier bearing, but the bearing must be inside the rubber boot. I can move the driveshaft side to side and up/down pretty easily, is this normal? The rear U joint has the tiniest bit of play, more of a tick than a clunk, and its only one direction. Could this little bit of play be making all that noise? Normally I would just change it because they are cheap and easy, but after looking at the one in the subaru... Looks like it has to be cut out, or drilled out.
 

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Onyx, 2008 LL Bean 3.0R and 2017 Honda Civic Hatchback Sport Touring
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Have you driven it since reconnecting the sway bar to the link? I drove with a broken sway bar and had a slight harmonic vibration noise. Let us know if that helps.

Wife had a tire loose a band shortly after purchase - probably hit one of the huge pot holes in Baltimore - and it made a low humming noise that got louder with speed. Try swapping the tires front to rear to see if you hear a difference. Just spit ballin' here.
 

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Discussion Starter · #6 ·
Didn't drive it after putting the link on, I decided to tackle the brakes right away and now its on jack stands waiting for a part to arrive Tuesday morning. I really hope its not that U joint, did a little research and it does not look fun :28: After the brakes are finished I may rotate the tires and take it for a spin, see what happens.
Any other ideas, I would love to hear them!
 

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00 Outback wagon, All-Weather
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maybe pinion bearing

I had a droning noise at resonant speeds, back when the car only had 150k miles. Expert transmission guy correctly decided not to tear into the transmission, but sent me to one of his buddies. His buddy diagnosed the front pinion bearing. $1,100. That hurt pretty bad, but he must have been right. We've run another 90k since the repair and it's still quiet. He said he does ONE PER WEEK, so he was pretty familiar with the symptoms. (we have lots of Subarus in our area due to local and regional dealers.)
 

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Discussion Starter · #8 ·
Woowwww! I really hope thats not it. Is it a pinion bearing in the tranny or diff? Either way I don't want to tear into them, I've had auto transmissions apart and thats something I don't want to do, unless I have a ton of spare time. How can I verify if this is the problem?
Now I'm kind of hoping it's the U joint, does anyone know if having a very small amount of movement can cause a lot of noise? The only time I've replaced bad U joints there was a good amount of movement.
Can anyone explain to me how much movement there should be in the carrier bearing? Should I be able to pull/push the driveshaft and have it move around in the rubber boot?
Lots of questions, I know..
 

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06 OBW 2.5, 05 Forester, had 03 H6 OBW
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Carrier and pinion more whine than drone, and usually make much more noise when on the gas and almost nothing when coasting.

Wheel bearings go up in tone very slowly as you speed up, pinions and carrier bearings the noise changes at a faster rate as they spin 4x as fast as the wheels.

bad front pinion on my 03

 

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Discussion Starter · #10 ·
Thanks for posting the video! Luckily thats not the noise. After getting the brakes finished I was able to drive it about 300 miles and it was definatley quiter thanks to the sway bar link, I can't believe how much of a difference that made! Still not 100%, still wondering about the U joint. It made the trip fine, but now the GF drove it another 250 miles and she says its clunking, loud. :28: So now I have something else to fix. :(
 

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Onyx, 2008 LL Bean 3.0R and 2017 Honda Civic Hatchback Sport Touring
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Double check the sway bar links. If they are not tight enough they can clunk. But that is usually when stopping or starting out. Check the brake pads to be sure they are seated in the calipers.

If something makes a new noise right after I've done some work I look for what has changed since the work was done. The obvious culprit would be a symptom of the recent work being done incorrectly. Eliminate the obvious before freaking out about a new problem. I know, easier said than done.
 

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Discussion Starter · #12 ·
I just wanted to follow up on this in case someone else runs into a similar issue.
It was kind of odd the sway bar link made it so much better, but a few weeks later vibrations started coming back and getting worse. Checked the rear U joint and there was a little more play, checked a week later and there was even more play. Ended up buying a used driveshaft (with a 30 day return policy) off eBay for 100$ shipped, threw it in there and then it ran smooth! I'm sure if you had the equipment and time you could get the old U joint out and find a replaceable one that fits, but 100$ for a used one was well worth it.
 
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