I have a 2004 TS, with about 35K on it.
Recently I've noticed that the engine/transmission doesn't sound right in a certain RPM range. Around 3000 - 3500, specifically right at 3250 the engine makes this kind of hollow buzzing sound. It's higher pitched than the usual sound the boxer makes.
The sound only occurs in that very limited range, and it doesn't make the sound ALL the time. Just yesterday I noticed the sound, but when I got back from my appointments and opened up the hood and revved the car with the throttle, the sound wasn't there.

Also the transmission has this buzzing sound after I downshift and let it engine brake. It also seems to happen in the 3000-3500 range. It sounds like two gears are bouncing off each other and makes this quick oscillating sound.

One more thing. When I shift into a higher gear, the rpms jump mabey 100 or so, and then the engine makes the higher pitched sound I was describing in the first paragraph.

The car works fine as far as I can tell. There is no loss of power or any REALLY harsh sounds. I don't really beat on it much, I will take it close to redline when merging on the thruway, but that's about it for abuse. I do A LOT of highway driving at around the same speeds and RPM range. Could this have an effect on how the transmission and engine wear and the sounds they make?

I'm drawing close to my warrenty being up and I don't want the friggin thing to explode on me right after it expires. I will bring it to the dealership before I hit 36K miles, but of course when you go to get it checked out is when the problem is never reproducable.

 

I was gonna say alternator static when a stereo is on but not turned all the way on. It sorta rises and falls with rpm but with your description i'm starting to wonder if its just gear whine.

I believe the first two gears are the loudest for whine on these transmissions if you mean downshifting your probably hearing the synchro's speed up the gears for shifting. All cars i've had do this to some extent even a few automatics.

 

Yea I don't think it has anything to do with the radio. I had the radio off while I was listening to the engine and transmission.

It probably is just gear whine and I'm not really used to the sounds subaru transmissions make. The higher pitched whining sound will still come around at ~3250 rpm even when the transmission is not engaged in a gear. I think that everytime I did rev the engine to hear that sound, I had the clutch pressed to the floor. So I'm not sure if it makes the sound when the transmission is in neutral. I will have to check that out.

Thanks,
Matt

 

Well, I took it to two separate dealerships because my warranty is about to lapse.
Both of them gave me the same opinion from my description of the problem

They say it is most likely a loose bolt or broken spot weld on the heatshield.
I tapped the heatshields on both sides of the engine, and one had a more hollow sound to it.
I've had other cars where the heatshield broke and rattled around like crazy, so I can believe the heatshield is the problem

Has anyone else encountered this before?

 

I know what it is!

its a damaged timing belt tensioner. get it fixed under warranty.

 

any update?