Whining noise coming from rear louder with speed (not evident during aceleration)

[vtwinjunkie]

1996 Legacy 2.2 that I am getting back on the road. 

 

Just got it inspected now I can work out the rest of the kinks. Today I noticed a whining noise coming from the rear. 

 

The noise starts at about 20mph. It gets louder as the car increases with speed. It seems to go away if I am harder on the throttle and come back when I coast. It remains evident even if I swerve the car side to side while coasting. 

 

At first I thought that the noise was coming from the rear passenger side (I was thinking wheel bearing) but now I am not so sure. 

 

I have yet to check the condition of the rear diff fluid but I plan to do this in the morning. I purchased some GL-5 to flush out the rear tomorrow just in case if it looks bad. 

 

Any thoughts? 

[1 Lucky Texan]

wheel bearings have a much higher failure rate than diffs, but nothing wrong with a close inspection of everything in the driveline.

[vtwinjunkie]

wheel bearings have a much higher failure rate than diffs, but nothing wrong with a close inspection of everything in the driveline.

I thought the same...But I am a bit concerned that with 180k miles I cannot find any maintenance that points directly to the diff fluid being done (which boggles me) since they did everything else it seems. 

[1 Lucky Texan]

you probably know, but loosen the fill plug before the drain plug. they are tight and have sealant on the threads - I had to use my floor jack on the handle of a 1/2" breaker bar. The 'correct' way is with a 13mm square tool - that few people seem to use.

 

one of these will help with the fill;

[vtwinjunkie]

So the rear diff fluid was dirty (but not black) and did not smell burned.

 

I guess I will be putting my money on that bearing being the culprit. 

[Fairtax4me]

Wheel bearing failure usually produces a low pitch grumble or helicopter type noise that increases frequency with speed. It may not always change with load conditions, but is typically not affected by throttle input.

 

A high pitch whine that changes with throttle will be the differential. Some noise from the hypoid gear set is normal. Excessive noise will usually be accompanied by glitter in the fluid as the gear set wears, and that would indicate imminent failure of the ring and pinion gears.

If the fluid came out clean, the noise is probably normal and nothing to worry about.

[vtwinjunkie]

Wheel bearing failure usually produces a low pitch grumble or helicopter type noise that increases frequency with speed. It may not always change with load conditions, but is typically not affected by throttle input.

 

A high pitch whine that changes with throttle will be the differential. Some noise from the hypoid gear set is normal. Excessive noise will usually be accompanied by glitter in the fluid as the gear set wears, and that would indicate imminent failure of the ring and pinion gears.

If the fluid came out clean, the noise is probably normal and nothing to worry about.

Thats the crazy part. I saw no glitter in the fluid at all.

 

But the whine is much louder than anything I have ever noticed during normal operating conditions of any vehicle that I have owned.

 

It goes away while I floor the throttle down (and is evident when I drive normally) and comes back as I am coasting.

[Fairtax4me]

Is it automatic or manual trans? Could be coming from the front differential? I know the manuals tend to make some whine from the front.

Autos can but it's less common. The front diff fluid is separate from the trans fluid on autos.

Edited September 4, 2016 by Fairtax4me

[vtwinjunkie]

Its an auto trans. 

 

What fluid is used on the front of those? GL5 correct? 

[Fairtax4me]

Yep, 80w-90 gl5. Problem with the autos is that normally if they start making noise it's usually the pinion bearing going out. They don't last long when that happens.

[vtwinjunkie]

Yep, 80w-90 gl5. Problem with the autos is that normally if they start making noise it's usually the pinion bearing going out. They don't last long when that happens.

 

Ill take a video of the noise. Its certainly the rear end though.

 

So if it is the pinion, what are my next steps? can I rebuild that? I feel like I can set lash and all that if needed I have done a rear end on a old ford back in college. 

 

Does it fail completely or just get louder and louder?

[vtwinjunkie]

I have attached a vid of the noise for your listening pleasure!

 

 

Edited September 5, 2016 by vtwinjunkie

[Fairtax4me]

That is loud isn't it! It's almost not quite differential, but not quite wheel bearing either?

It's an automatic, have you tried running it with the FWD fuse in to see if it changes?

[vtwinjunkie]

That is loud isn't it! It's almost not quite differential, but not quite wheel bearing either?

It's an automatic, have you tried running it with the FWD fuse in to see if it changes?

Great idea. I thought about it but havent tried that yet. I will give it a shot tomorrow after work.

 

curious though... If that changes it, what would it be indicative of? 

[1 Lucky Texan]

what kind of noise does the carrier bearing make when bad?

[vtwinjunkie]

what kind of noise does the carrier bearing make when bad?

 

Are you asking me? is this a question? 

 

sorry I am not sure, hence the reason for my questions. 

[Fairtax4me]

Was kind of thinking carrier bearing too.

It's the center bearing on the driveshaft. That one might make a noise closer to what you have, and could be influenced by heavy throttle. The only good way to check that is to get the car up on 4 jack stands, put it in drive and get the wheels up to about 30mph and crawl under with a mechanics stethoscope.

 

With the FWD fuse in I think the noise should not change any under heavy throttle.

Edited September 6, 2016 by Fairtax4me

[vtwinjunkie]

Was kind of thinking carrier bearing too.

It's the center bearing on the driveshaft. That one might make a noise closer to what you have, and could be influenced by heavy throttle. The only good way to check that is to get the car up on 4 jack stands, put it in drive and get the wheels up to about 30mph and crawl under with a mechanics stethoscope.

 

With the FWD fuse in I think the noise should not change any under heavy throttle.

Thanks for the explanation!

 

That is my next step

[vtwinjunkie]

Update. 

 

Took it to a shop that a buddy works at and got it up on the air. He and I both listened through a stethoscope and it sounds like the Pinion bearing (perhaps subaru calls it either pinion or the intermediate bearing). 

 

Trying to figure out which rear I have as I may be getting another from a junkyard.  If the price is right.