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Mysterious High Pitched Whine- 2005 Subaru Outback

About 2 months ago, I noticed a high pitched whine on my 2005 Subaru Outback. It honestly sounds like a siren and is very noticeable. It occurs more often when the car is cold (1st thing in the morning) and around 20 mph. It sounds like it is coming from the rear of my car. It occurs whether or not I am pressing on the gas pedal. Once I get above about 30-40 mph, I don’t notice it anymore (don’t know if this is because other engine noises are drowning it out or what). It does not change or get worse when I turn. It seems to subside once my car is warm. Other people have heard it and some describe it like an airplane taking off. I took it to the Subaru dealership and they said it was my alternator. Lo and behold a few hundred dollars later, it was still making the noise. A few days later, my CAM sensor went bad and I was back in the shop. Of course, I tried to get my car to make the noise for the mechanic, but it wouldn’t cooperate. They didn’t see anything wrong, but it is still making the noise. I have taken it to the dealership and they couldn’t get it to make the noise. My rear wheel bearings were going bad and so I replaced those- thankfully under warranty, but it still makes the noise. I keep up with all my oil changes, services, etc. I just had the fluids checked and the power steering fluid is normal. The power steering pump has also been checked and it is normal. Any idea what this might be? Thanks in advance!

Here is the noise. I’m recording it as I’m driving.

The only thing that I can think of in the back of the car–aside from the rear wheel bearings–is the rear differential. When the fluids were checked recently, are you sure that they checked the rear diff? Then again, a differential noise would not go away at high speed, but I am hard-pressed to come up with anything else.

You do have to bear in mind, however, that with a unitized body, sounds may seem like they are emanating from an area other than where they really originate, so things like the bearings in the pulleys and tensioner for the serpentine belt should also be considered.

Okay. I will have that checked. Someone also suggested that it could be the drive shaft, but hopefully that proves to be false. I feel like I hear it from the front, but I am always driving. Another person thought it was coming from the rear as they were putting their head out the window to try to determine where it was coming from. Thanks for your input.

Perhaps see if you get try this in an empty parking lot, where you get it up to speed and have an observer hear what wheel makes the noise.

Subaru half shafts have this lip on one end that fits over a mating surface of the the wheel hub assembly. I know that, if this lip is slightly bent, it will make noise but it is more a raspier, louder noise and it is also at all speeds.
It could maybe be your brake alarm tab but one would imagine that a mechanic would look at that first, though.

An additional thought is that you could have a fuel pump that is giving indications that it is dying.
Since the fuel pump is located in the rear, this is another part to have the mechanic listen to carefully.

Since the problem seems to occur mostly when everything is cold, you should really leave the car at the mechanic’s place overnight. Then, show up the next morning at opening time, and have a mechanic go for a ride-along with you, so that he can hear the noise when it is most likely to show up.

Automatic or manual tranny? Manuals are famous for whining when the synchros wear out.

The differential can be readily inspected by any competant shop. It requires draining the diff fluid, pulling the cover off the case, inspecting the wear pattern on the ring & pinion gears, and checking the pinion shaft for play axially and laterally.

The wheel bearings can be checked by lifting the wheels with the parking brake off and pulling on and spinning the wheels by hand. If the wheel seems loose, it’ll be the axle shaft rattling in a worn bearing assembly. If spinning the wheel by hand makes it grind, the bearings are bad. If you can feel a rough feel at teh hub when turning the wheel by hand, it’s the bearings.

The driveshaft again requires getting under the car. And shaking the driveshaft.

As yp noises eminating from under the hood, they can be generally identified by touching things iwth a mechanic’s stethescope. They generall cost around $10 and have a think hollow metal rod that activates a diaphragm that sends the noise to earpieces. And they do work. I would have touched the alternator with one before okacing blame there.

The only thing I will add to the good advice already given is that if the problem is due to the final drive in the transmission (assuming it’s an automtatic here) then the car should not be driven.

The final drive in the transmission is separate fluid-wise from the auto trans section and each uses their own type of lubricant.
It’s somewhat common for someone to drain the final drive by mistake while performing an oil change.
If this whine seemed to appear not long after an oil change then it’s certainly something to consider.

Depending on the interpretation of the location, it’s also quite possible for a front final drive whine to sound like it’s coming from the rear. If this whine only exists when the car is rolling and not at a stop then a final drive problem due to lack of fluid is a possibility anyway.

You really need to check the final drive oil level on the transmission and this is NOT the ATF stick.
Continuing to drive with a whining ring gear in a situation like this can lead, and has led, to catastrophic consequences with the transmission being utterly destroyed.

I might add the link as an aid to helping you find the critical stick for the final drive oil.
It’s the stubby yellow one on the passenger side of the transmission right underneath the green electrical plug; generally out of sight and out of mind. The other more obvious stick is for the ATF.

Thank you for your help. I will definitely check those things as well. It is an automatic. I have left it at the dealership overnight and driven with a mechanic on 3 different occasions- with no luck. I’ve had the front axel and the front wheel bearings replaced in the last 9 months, so hopefully those are still in good shape. The technician at the Subaru dealership was the one that mentioned the drive shaft to me. He said they had a Subaru in the shop a few weeks ago that was making the same sort of noise he heard on the audio clip. He just said to bring it back in if it was doing it more consistently, but that was his best guess as to what was going on. I hope he at least inspected it if he was suspicious that that might be the problem.

@Jamers87, did the shop reinstall the original alternator and refund your money?

I am asking other mechanics if there could be a baffle in the muffler causing it? Just a thought. I have heard them make some pretty wierd and loud noises when the baffles are bad. And it could be moving around inside the muffler only making the noise when cold.

No, unfortunately they did not. They maintained that they heard the alternator whining even when I told them that I was having no problems that would indicate that my alternator was going bad.

@Jamers87, the shop fixed the wrong noise. You should try to get reimbursed.
You paid for them to eliminate a noise. They eliminated the wrong noise.
Bottom line, you didn’t get what you paid for.

That was my argument exactly. This was even done at the Subaru dealership.

My subaru 1998 outback legacy is doing the same when I hit 30-40 mphs. I’m thinking that it’s due to the fact that I need more coolant. Just wondering if you ever figured out the issue. So i dont go on a wild goose chase and spend tons of money. Also it definitely sounds like it’s coming from the front on the right side.

A whine would not likely be due to low coolant.

That could be a wheel bearing or a differential whine. You need to read my above posts about gear oil on a Subaru transaxle. A front differential whine can appear to be from the right front.

This is CRITICAL. If the gear oil is low it’s possible for a transmission mainshaft bearing to seize up. (Manual transmissions)
If the gear oil is VERY low or near out the ring and pinion gear can disentegrate and when this happens the damage will be catastrophic; as in scrap metal. As a Subaru tech I’ve been involved in a number of these.

It only takes a few minutes to check the gear oil. This will be the dipstick on the passenger side, down low, near the right side inner CV joint.

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Alternator is working.
Dealer says it is causing noise.
You say it is not
Replacing it has no effect on noise.
You pay for it
You now have a new alternator.
Dealer says a new alternator is better than a 12 yr old one

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You know that your cooling system is low on coolant, and yet you are continuing to drive the car?
Why would you do that?



I know it’s dumb, but I just checked it yesterday. So I’m fixing it today. Money is a struggle.