strange harmonic noise at certain speeds

[vdcwgnh630]

hi - I'm new here but I've got a problem and I suspect someone might be able to help me.

 

2002 Outback VDC wagon 3.0 liter H-6 motor - 125,000 miles

 

My car just recently began making a barely audible alto-pitched harmonic-hum between 60-70mph only. The noise can increase in volume with a little extra throttle and the volume will fade if you back-pedal just a tad - all along staying between 60-70 mph. Increase the speed to 75 and the sound is gone completely. Decrease the speed below say around 55 and the sound disappears completely. Take your foot off the gas completely and the sound disappears as well, only to return if you feed it just a little. Very strange. The pitch of the sound does not vary much with the increase or decrease in speed and its not tire noise 'cause when you let-off the throttle it disappears (besides I can hear the tire noise separately, it sounds different). I do not notice the sound whatsoever at any other speed range. The car seems to be performing well, runs strong at 40mph and just as strong at 90mph with no noticeable performance issues.

I thought perhaps it was a belt or possibly a wheel bearing. I turned off the A/C thinking perhaps its a compressor pulley or something and that has no affect. I just replaced a rear wheel bearing back in the Spring and that had a distinct vibration where the pitch would increase and decrease with my speed, regardless of throttle position, so I'm pretty sure it's not that. I cringe to think it might be the tranny or differential, but I guess only time will tell.

I drive nearly 400 miles a week, so I'm sure I'll be finding out sooner than later what the true diagnosis is, but if it's something serious I'd like to nip it in the bud.

Any thoughts, suggestions or comments would be appreciated.

Thanks -

[sea#3]

Does the noise change in the 3 position on the gear shifter and holding the same speed range?

Also check the levels in the front diff and transmission

 

SEA#3

[brus brother]

Automatic tranny? Pinion gear on my 2000.

[vdcwgnh630]

Does the noise change in the 3 position on the gear shifter and holding the same speed range?

Also check the levels in the front diff and transmission

 

SEA#3

 

Today I tested this. In position 3, the car does make the same noise, although the speed range is wider is seems.

Actually today I did some extensive testing and found that the noise is occurring between 45 & 75 mph. Today I was also able to distinguish a slight change in pitch of the noise from the lower end of the range to the higher end of the range. Keep in mind....when you let off the gas the noise goes away entirely.

I'm able to duplicate the noise in that same general speed range regardless of whether its in drive, 3 or 2 for that matter, although I didn't have the room to wind position 2 up to 70mph.

I also noticed today that the noise appears to be coming from the front passenger wheel-well area, so I'm starting to think CV joint maybe or something in the transaxle. I'm not a mechanic so any further speculation would be just that.

 

To summarize - it appears that the problem occurs when the car is under power, not coasting and that the noise is related to the drive train on the front passenger wheel and that the noise is only audible at speeds between 45 & 75. I do not have any other pertinent information at this time, but I will be monitoring it carefully.

 

Thanks -

[TheYeti]

I have the same type of noise with Don ('97 OBW) at just about the same speeds and exercises the same behavior. Don's happens to be the rear diff.

 

I haven't worried too much about it since there doesn't seem to be any grinding or popping going on. I have just been a little more deligent about changing the fluid and such... I bought the wagon with 168k on the ticker. Now he has 204k and still runs strong.

[vdcwgnh630]

well -for an update...

I took my car to the dealer and had a Subaru mechanic take a ride with me.

He said right away that it was a bearing in the transmission. I didn't even have to get on the highway he was able to detect it at low speeds.

Anyway....the service manager told me that "they dont do transmissions" and that my options were to take it somewhere that does do transmissions and take a gamble on the work, or have them drop in a refurbed tranny to the tune of nearly $4K. The mechanic also told me that doing a tranny flush & fill might "help" the situation or it might make it worse. I made an appointment to get the tranny flushed and filled along with the differentials just for good measure and I'm going to play wait and see for now and weigh my options.

 

Couple of things I've been considering:

I am going to take it to AAMCO, just for a second opinion. I find it hard to believe that AAMCO will just fix the problem...I'm guessing their solution is a complete tear-down and rebuild with all new bearings, etc. Does anyone have any experience here? Is going to a repair shop really worth it or should I just do the refurbed tranny from the dealer?

 

Is going to the junk-yard and finding a tranny a good idea? Obviously this could be the least expensive route, but you're taking a gamble on the quality, no? Do tranny's "store-well" after they've been yanked out of a car and put on a shelf waiting to be sold?

 

Any thoughts here would be appreciated. I'm really fscking pissed that the tranny is failing....I'm still paying for the car (bought it used) and this is most definitely the first 'major' problem I've ever had with a subaru - and I'm on #5 so I'm no rookie.

[nipper]

NOOOOOO!!!!!!!!!!!!!

 

Get away from the aamoco station now or we will be forced to put your subaru in protective custody and give you a pinto.

 

They are the absolutly WORST place to go. If you google them you will see endless complaints against them. Your car can be perfectly fine and they will still sell you a transmission.

 

go someplace else.

 

nipper

[TheYeti]

If you are considering a referb, talk to the folks at CCR. I know they will rebuild Subaru transmissions in addition to the engines and the service they will offer to you if something goes wrong with their product is fabulous. I also know it won't cost you 4k...

 

Before any of that, I would suggest changing out the fluid to see if that helps quiet things a bit.

[ron917]

Just in case you didn't get what Nipper said,

 

STAY AWAY FROM AAMCO!!

 

There are many, many horror stories about them on the Web. I have my own, but it's from 25 years ago, and I will never go near an AAMCO shop again.

 

Nipper was almost right - your car can be perfectly fine, but they will still sell you a transmission AFTER TEARING YOURS APART so that you have no choice but to pay a huge bill.

[vdcwgnh630]

ok- ...so I see you guys feel pretty strongly about AAMCO........Duly noted.

 

I've contacted my long-time mechanic shop who are really the only people I've ever trusted to work on my cars. They are trying to source a used transmission from a junk-yard for me. They dont *repair* transmissions although they will refer me to a shop that they have worked with for many years and trust their integrity.

 

I guess I'm torn between forking out much cash for a refurbed tranny, taking a gamble on a junk-yard tranny, and fixing this one.

 

I honestly dont know what the right answer is here....leaving cost out of the equation makes the newly refurbed tranny a no-brainer...but its a lot of cash I currently dont have - so I'm looking at other options.

 

Is a junk yard tranny a huge gamble? Is repairing this tranny a worthy excercise? I've never had tranny problems before.....so I'm truly not in the know on this one.

 

thoughts?

Thanks for the above advice....I do appreciate it.

[nipper]

Look in your heart luke.....feel the force.

 

 

What is the goal of this car. Do you want to drive it untill it hits 400,000 miles, or another few years and replace it. Used subaru trannies are very reliable. you must get a warrenty and a yard that stands behind it. The first time you make a u turn youll know if its good or not.

 

nipper

[elborak]

Given that the noise is, according to your description, "barely audible", and that you are considering either a refurb or a junkyard tranny (as opposed to having yours rebuilt), what's the hurry? What damage are you likely to do by just running it.

 

I would probably just be diligent about fluid changes and run it until the problem becomes noticably worse. And that may never happen.

 

But I'm a relative newcomer to Subaru's (just 2 years), so I'll defer to the experts.

[ron917]

The only time I every had noise from an automatic transmission the fluid was low (cooler pipe was leaking). Did you check the fluid level?

 

The tranny problem that led to my AAMCO horror story mentioned earlier didn't exhibit any noise, it just wouldn't shift out of 1st gear (that was an old Chevy, if anyone cares).

[nipper]

I would just drive it till it got worse, unless you have TB then its time to shop for a tranny.

 

 

nipper

[brus brother]

Automatic tranny? Pinion gear on my 2000.

My 2000 AT was replaced under warranty at 35K for known problem of delayed engagement and then at 50k under extended warranty for the pinion gear noise and then again under extended warranty at 76K for a clicking noise.

Putting a used one is like marrying someone else's ex.

You may be in store for some suprises after you spend hours tranny swapping.

[vdcwgnh630]

Since I have some people who are interested, first of all I want to thank you all, the advice is much appreciated. I know I'm not going to get sound advice from the dealer's service dept. and while I like my mechanics a lot, they dont specialize in subaru's so I have to be concerned with any generalized statements or suggestion they make - subaru's aren't just another import car - the AWD functionality is not standard on most cars and dealing with it from a mechanics perspective shouldn't be taken lightly.

 

A few answers to questions:

1. - yes.....I am getting the tranny and both differentials drained and refilled by the dealer next week. This is my first step at 'correcting' this problem, if indeed it is correctable. The dealer's service manager told me they have some special tranny stuff they will throw in there to help bind things up....I guess its just like auto-metamucil or something.....whatever I dont give a ************ - as long as it works.

 

2. - When my mechanic gets back to me if he is able to source me a good used tranny from a junkyard....I will consider it....especially if the price is right.

 

3. - I just drove home from down the shore cranking some Pat Metheny so I couldn't hear anything under the hood, and the car rides sweet. There is absolutely no noticable difference in the way the car drives and with that McIntosh stereo cranking and the roofs open, I almost forgot I had a problem. I wish I could just ignore the noise, but on a work day when the A/C is on and the windows are shut and I could be talking in my headset with a client, the gear noise and that strange harmonic hum like a tuning fork under the dashboard just bugs the crap out of me. I can't help but think the tranny is just going to explode the way the gear noise revs up and down with the speed of the car. Drives me nuts.

 

So - I guess it's a wait & see thing with the fluid change next week....that will tell the story real quick I suppose. At 500 miles per week of driving, I can't help but think the tranny is going to give me a bigger sign sometime soon.

 

Thanks again for the feedback - I'll report back if anything new develops.

[elborak]

I think part of the reason you are getting multiple suggestions (other than just the normal differences of opinion) is that your description seems to be changing. It's gone from "barely noticable" to "I can't help but think the tranny is just going to explode". That's quite a difference!

[vdcwgnh630]

I think part of the reason you are getting multiple suggestions (other than just the normal differences of opinion) is that your description seems to be changing. It's gone from "barely noticable" to "I can't help but think the tranny is just going to explode". That's quite a difference!

 

ok - you got me there. The noise has indeed become more pronounced and there is also the addition of gear-noise that I hadn't noticed originally.....so yes, the situation is changing. The tuning-fork hum is still there and is still " barely audible" above the regular road-noise one would expect. The gear-noise observations I've made this week were probably there before, but being that its summer and I usually have the window and/or roof open, I wouldn't ordinarily notice it unless I was hunting for trouble.

Anyway, I dont mind the multiple suggestions since I obviously have a problem and it's most definitely changing with time.

 

BTW - I checked the transmissions fluid levels and they are at the High mark for "hot". The fluid looks a little dirty but it's getting changed out early this week, but I wanted to report that the level is at least...correct.

 

Thanks -

[nipper]

Does the noise tend to roar and change volume with road speed. If it does thats a differntial. Its a very unique noise.

 

 

nipper

[vdcwgnh630]

well - figured I'd update this thread for the greater good.

 

Turns out, my Subaru dealer referred my problem to a guy locally who does transmissions and engine rebuilds and has been for 25 years. I double checked with my regular mechanic and he knew of this fellow as well so I felt good about going to see him.

 

Ended up rebuilding the transmission. The rebuild was less expensive ($2500 vs. $4000 for a new tranny from the factory) and the warranty on the rebuild was 2-years or 24,000miles vs. the factory tranny at 1-year / 12,000 miles. 24K is less than a year of driving for me so I really needed the better warranty.

 

All I can say is - ouch. The new tranny is rock solid and has 1200 miles on it already....no leaks and the mechanic insisted on seeing me in 10 days for a road-test and free oil-change so he could inspect his work. One good thing has come out of this whole thing.....I think I've got a new mechanic....this guy certainly is meticulous and really seem to give a damn. I'd also like to thank my local Subaru dealer for recommending him since they "dont do transmissions"

 

I've owned 5 Subaru's and I've never had a major component failure like this one.....so unexpectedly....this one hurt. Still - my ride seems as good as new now even if my wallet is a whole lot lighter.

[Olnick]

I've owned 5 Subaru's and I've never had a major component failure like this one.....so unexpectedly....this one hurt. Still - my ride seems as good as new now even if my wallet is a whole lot lighter.

 

Happy you have a rock-solid tranny now. Sorry you took such a hit to get there. Did your new mechanic give you any info on what went wrong with your original tranny?

 

Thanks for updating us and . . . happy trails!