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Premium Member
2006 Forester XT 5-Speed Manual
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380 Posts
Discussion Starter · #1 ·
Hi all,

I have an 06 XT 5MT. 203K on the body.

Tranny rebuilt at 133K by Andrewtech
Engine rebuilt at 162K by Andrewtech
Replaced rear diff at about 180K with a used one with 50K miles.
VF39/STI TMIC/etc...K&N short ram intake
30K miles on my tranny fluid and 25K on the rear diff oil

Lately I've noticed a high pitched whine when accelerating. It doesn't seem to be there when I rev the engine (I need to really test this better, but I don't think it is there when not in gear either moving or stopped). It is also not there when not pressing the accelerator. I thought that it was my alternator as my voltage would drop slowly and end up below 13v. So I had that replaced with a reman and the whine is still there. It is a very faint whine. With the windows up, I don't hear it. (so drive with the Windows up :grin2: )

I've seen that some people have this whine with a filter that needs to be replaced (or cleaned in my case as I have a K&N cone). If it were the filter, would I not also hear it when revving the engine (not under load)? I know that my filter cleaning is overdue. Probably way overdue. I am going to do that tomorrow.

Any thoughts?

Thanks,
 

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When accelerating how hard? Mild acceleration in the same gear or dropping a gear and WOT? Pardon me in advance if this is all super obvious stuff that you already know but: My car has always produced some combination of whining, whooshing, or whistling sounds, all of which can be normal turbo noises. Whining/whistling as turbo spools sometimes, and whooshing as the intake sucks down air. Any chance these are normal turbo noises you never noticed before? The fact that it inly happens under load suggests to me that it is turbo related.
 

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Premium Member
2006 Forester XT 5-Speed Manual
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380 Posts
Discussion Starter · #3 ·
Pardon you for trying to help me? :grin2:

I am wondering if I've had this whine before. Last year, I retired my FXT from my daily driver to weekend fun car. I drove it very sparingly over the winter. I just put my summer wheels/tires on and I am starting to drive it more on the weekends now. So maybe, because I haven't driven it much, that I am not used to the noises.

It happens from half (or a little over half) to full throttle. It seems separate from the turbo. Since I have a K&N short ram, the turbo produces a very loud whooshing sound and it is distinctly different. My first instinct was that it sounds like a gear whine. Normal highway driving is silent. If I punch it, I hear the whine. Now at WOT is is very difficult to make it out over the turbo spooling.
 

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2008 Forester AT
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23 Posts
This probably isn't much of a help but mine produces a high pitch whistle only when accelerating under load- aka just revving the engine doesn't recreate the noise. But lets say going up an entrance ramp to get onto the highway does. Except I can hear mine over the radio and with my windows up.
Its the rear cat converter- it whistled before I replaced it and I thought replacing it would fix it, but now it still makes the noise. My car performs excellent and the cat converter is in great shape too so its not really a problem per say but it makes that noise and I had this noise also confirmed by Subaru techs.
 

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Super Moderator
2001 Forester S, 4EAT
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2,942 Posts
I had a whining noise on my 2001 vehicle. In my case it turned out to be a worn out AC idler pulley. So you might want to check the bearing on the pulley.
 

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Premium Member
2006 Forester XT 5-Speed Manual
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380 Posts
Discussion Starter · #6 ·
This probably isn't much of a help but mine produces a high pitch whistle only when accelerating under load- aka just revving the engine doesn't recreate the noise. But lets say going up an entrance ramp to get onto the highway does. Except I can hear mine over the radio and with my windows up.
Its the rear cat converter- it whistled before I replaced it and I thought replacing it would fix it, but now it still makes the noise. My car performs excellent and the cat converter is in great shape too so its not really a problem per say but it makes that noise and I had this noise also confirmed by Subaru techs.
Thanks. That makes me feel better. This car makes me so anxious. I've spent soooooo much money on it. Original owner since Feb 2006. At first I had convinced myself that it is the transmission.
Car performs fantastically. A/F is perfect. (according to my AP). Boost is great. No knock.
Taking it in for tranny and diff fluids in a few weeks. (Andrewtech)
 

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Premium Member
2006 Forester XT 5-Speed Manual
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380 Posts
Discussion Starter · #7 ·
I am back to being convinced that the whine is not normal....
I tried recording a clip. It is hard to hear, but it starts at about the 4 second mark. I might try to make a better clip tomorrow. So, it appears to not be RPM related. Only happens when I accelerate. When I let go of the accelerator, the noise stops.
I had to record inside of the car, where the noise is quieter, because sticking my phone out of the window only gets wind noise on the recording.
 

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2018 X3 M40i / 2016 X3 xDrive35i
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1,632 Posts
Check to see if it's gear dependent.

If you take off your shift boot console and the noise is amplified, it's coming from the transmission, even if it sounds like it's in the dash as it resonates there.

Mine has a whine when accelerating in 5th gear only, which is amplified with the boot off 10 fold. It is on accelerating and the pitch changes as RPMs climb but then goes away at speeds over 80. My theory is transfer case input/output roller bearings.
 

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Premium Member
2006 Forester XT 5-Speed Manual
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380 Posts
Discussion Starter · #9 ·
Thanks. I removed the shift console and lifted the rubber boot underneath. Noise was the same. Whew.

I will have to re-test. I thought that it might have been slightly louder when turning left. I am having a hard time describing this whine. Sometimes, I think that it sounds like an alternator whine and other times like a gear whine. It is faint. Most people wouldn't even notice it. But on a car this old and with this much money sunk into it, I notice these things :grin2:

I made an appointment for 2 weeks from now at Andrewtech.
 

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2018 X3 M40i / 2016 X3 xDrive35i
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1,632 Posts
Well....in this case I might have given the whew if the noise increased as that would suggest a bearing or gear lash problem which is fairly inconsequential in the short term.

Hopefully it's not your turbo..
 

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Premium Member
2006 Forester XT 5-Speed Manual
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380 Posts
Discussion Starter · #11 · (Edited)
Thanks.

I don't think it is the turbo as after some more testing (and with my kid in the car whose hearing is better than mine), the noise gets higher pitched (and sounds faster as my daughter described it) the faster I am going. I have to be accelerating but in order to really hear it, I need to not be in boost. So I am only lightly on the accelerator. (I have a short ram intake which makes my turbo spool loudly) I really only hear it in gears 2-4. My guess is that in gear 1 I am not going fast enough to notice and by 5th gear, I am thinking that the noise is so high pitched that I can't hear it. My hope is that if it were the turbo the whine would not be speed related.

I want to say that it sounds like the whine you'd hear in a straight cut gear but which is speed related (and not as loud). So 4th gear is very high pitched while 2nd gear is not as high pitched.

Since it seems to be speed related, is the transmission less likely? Is it safe to assume that it is something that moves faster as the car moves faster such as the axle, wheel/tire, rear diff (seems to be coming from the front through). etc...
 

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Premium Member
2006 Forester XT 5-Speed Manual
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380 Posts
Discussion Starter · #12 · (Edited)
I had my car in the shop and unfortunately, they didn't hear any noises. I was not there to drive it and point out the noise myself. I dropped the car off after hours and picked it up after hours (was having the rear diff and tranny fluid replaced). It was also raining pretty hard that day so they had to drive it with the windows up.

Anyways, I still have the noise.
Today, I was having lunch with my cousin who up until 6 months ago was a mechanic (34 years experience). I explained the symptoms to him (I didn't have the car with me) and he immediately said pinion bearing.
So I went to youtube to check out some videos of pinion bearing whine. One or two sound like mine. I am not sure as it seems like the noise is coming from the front.

I might swing by Andrewtech and drive them in the car.
 

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Whining noise under mild excelleration

Hey Dinotheo,

I have the same issue with a 2005 FXT with a 2004 STI engine in it. Noise is audible in 2-4 gear, under mild acceleration, and seems to be tied to the engine RPMs. Gets quite high pitched before going to the next gear. I am at wits end, did you ever find out what it was?
 

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Premium Member
2006 Forester XT 5-Speed Manual
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380 Posts
Discussion Starter · #14 ·
@masterofmaker I am in the same boat haven't found what is causing it. Mine is related to speed. So in 3rd it is higher pitch sound than 2nd. Only under acceleration. If I let go of the accelerator the sound goes away.
Right now, I am just going to stand pat. If it gets worse, then I'll get more aggressive in tracking it down.
 

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2013 Forester 2.5XT Auto
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136 Posts
@dinotheo I have a similar sound to what you recorded happening with my ‘13 2.5xt. i first noticed the noice after my 105k maintenance when I replaced the spark plugs and all belts. Did you ever happen to find out what was causing the noise?

Forgot to mention that the noise in my car starts when I reach 35mph under steady but mellow acceleration
 

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Premium Member
2006 Forester XT 5-Speed Manual
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380 Posts
Discussion Starter · #16 ·
@bhardy Mine ended up being the center differential. I had my car in to replace the clutch and they noticed a problem with the center diff. I didn't know that this was the cause of the noise, but after I got my car back, the noise was gone.
 

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@bhardy Mine ended up being the center differential. I had my car in to replace the clutch and they noticed a problem with the center diff. I didn't know that this was the cause of the noise, but after I got my car back, the noise was gone.
Did they replace the center dif? My 09 XT is making the exact same whining noise on acceleration.
 

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Premium Member
2006 Forester XT 5-Speed Manual
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380 Posts
Discussion Starter · #19 ·
Did they replace the center dif? My 09 XT is making the exact same whining noise on acceleration.
Yes. Unfortunately. it ended up costing me much more than I would have expected.
 

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2004 Forester XS 5MT
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1,063 Posts
Great. Always had this and figured it was just the AWD system never having owned a Subaru before. I jokingly called it my secret centrifigul supercharger. Car drives 100% so not sure i should worry, but they go for about $500 on fleaybay new, so I would image 1-1.5k to swap. Should I be concerned, car has 191k in it?
 
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