In the last few weeks I've heard a whirring noise in my 01 outback while accelerating. When I take my foot off the gas, the noise nearly disappears. While accelerating, it gets louder the faster I go and is constant. Any ideas??

Does it change any if you turn?

 

Kinda sounds like a wheel bearing from the initial description.

May be low on ATF. Another possibility is a bearing in the alternator failing.

How many miles on this car?

 

and welcome

 

nipper

No change while turning, not a wheel bearing. ATF was a little low, I added half quart to top it off. There are 230K miles on the car.

the front diff may be showing its wear. make sure the fluid level is correct. check the SHORT dipstick on the TOP of the trans. if you did not know this was there, then this may be your problem!

It is hard to tell over the net. If the volume increases with road speed it can be the front diff. If it varies with engine RPM it is the front pump on the transmission. Either way it points to a replacement. good news if it is a diff it can stay like that for quite some time.

 

 

nipper

Just to piggyback on this thread, I have a similar symptom under different circumstances. 99 legacy gt 380,000 kms, droning sound at 60 kph in third gear, goes away when I shift to drive. I am one of those poor saps that wanted a standard but wound up with an auto and cycles through the gears manually to inject a little fun into a boring transmission. There is nothing wrong with the bearings (yet), but there is vibration under acceleration. I recently replaced the rotors, calipers, and pads, so that is not the culprit. New snow tires, recently balanced. Any ideas?

Just to piggyback on this thread, I have a similar symptom under different circumstances. 99 legacy gt 380,000 kms, droning sound at 60 kph in third gear, goes away when I shift to drive. I am one of those poor saps that wanted a standard but wound up with an auto and cycles through the gears manually to inject a little fun into a boring transmission. There is nothing wrong with the bearings (yet), but there is vibration under acceleration. I recently replaced the rotors, calipers, and pads, so that is not the culprit. New snow tires, recently balanced. Any ideas?

 

Does it make the same noise in 1st and 2nd as third at the same engine Rpm?

 

nipper

The sound can be heard in all gears, it just really stands out in third. It's a low droning sound like a wheel bearing, but doesn't subside in turns like a bearing would. Sometimes I can make it out at highway speeds, but usually wind noise and kids drown it out. I put it on jackstands last weekend to check the bearings but couldn't find any play and no sign of any other wear items going south on me. Perhaps a transmission and differential flush might be in order?

I had a bad wheel bearing that droned while driving, for a while did not change while turning, and was undetectable by turning the wheel manually until I raised both fronts, put it in N, spun a wheel like heck, and then put my hand on the strut spring.

 

Placing something on the strut (long screwdriver or socket extension) and folding your finger over the end and then sticking your knuckle in your ear magnifies whatever sound may be there quite a bit.

 

 

Dave

Could be rear diff, have you check the fluid level?

the front diff may be showing its wear. make sure the fluid level is correct. check the SHORT dipstick on the TOP of the trans. if you did not know this was there, then this may be your problem!

 

 

my wonderful 2003 Forester XS made this same sound.. it got louder and louder.. so I took the next exit off and pull off.. As soon and I moved forward with only like 5% throttle the front diff just exploded..

 

 

It was an Auto too which sucked.. the dip stick was under the low mark and all because of the leaky seals..

Do you have a parking garage you can drive through ot something with a good echo so we can get a little better fix on the noise? A front pump will have a differnt sounds then a diff, as a diff will roar, and a pump tends to scream.

 

nipper

Sorry for the delay, was in Toronto for the weekend. So I checked the fluid levels in both diffs, no issue there. The sound is most definitely more of a roaring sound, but the strange thing is that it occurs as a wave. If you are mathematically inclined think of a sine wave. As it increases in volume it drops in tone, sort of like when you hear somebody with a loud stereo getting closer to you. Just a low sound wave. This is certainly coming from the front of the vehicle. It has the quality of metal rubbing on metal as opposed to a grinding. And it instantly drops in intensity if I shift up a gear when holding steady at about 3500 rpm, almost to the point where I cannot hear it. In my experience, a bearing would continue to intensify in sound as velocity increases regardless of rpm; a driveshaft likewise continues to increase it's rate of rotation as well. So if we can eliminate those as a problem, where to now?

Does it do this on a dead straight road?

 

Are your tires cupped?

 

Check for heat shiled issues.

 

This is a noise of harmonics.

 

Longshot check your main pulley.

 

nipper

I'm running my snow tires now and this was happening with the summer tires as well. I had them balanced when they went on the car and there was no sign of cupping. I can eliminate the heat shield factor conclusively because I no longer have any (I am very impatient when it comes to annoying rattles). I had never really given any thought to the main pulley...I am going to break down and take it to my local dealership and have them put it on the hoist to check this stuff out. I am related to the service manage (distantly) and he is usually good about not hammering me on diagnostic time. My wife and I commute over 100 miles daily with this car, so spending a little money for piece of mind is worth it. I'll let you know what they have to say.

Just got back from the dealership and can't quite believe I never picked up on this; it's the alternator bearing. They ran around the car with a stethoscope and quickly came to this conclusion. You can even feel it at idle when you put your hand on the belt guard. Made a few calls and I can get one for about $75.00 from a local jy:banana:. They also found a cracked axle boot, so I have a pain in the arse Saturday coming up in the near future. Thanks for all the feedback. You were really on to something with the main pulley. Right church, wrong pew.

thanks to all for your comments. the sound does get louder/quieter depending on road speed. From reading the posts I think the differential fluid replacement is a good place to start. More questions, is the yellow dipstick under the airfilter box is the refill for the front differential? Where do you refill AT fluid?

Any way to test to rule out the alternator bearing?

Remove the drive belt and start the car. If it goes away BINGO

 

nipper

Any way to test to rule out the alternator bearing?

 

remove the belt and drive around the block. take the alternator, tools and jumper cables with you just in case.