Help me diagnose this noise...

[alphatarget1]

05 Subaru Legacy GT. Whirring noise at WOT but no apparent driveability issues (no lost of boost that I can feel, at least). What could it be?

http://www.youtube.com/watch?v=Ea533UnCIsg&feature=youtu.be

 

[nickbits]

bulk beef in the fuel injector

 

[alphatarget1]

bulk beef in the fuel injector

Can you elaborate?

 

[nismotigerwvu]

Ignore the trollpost. Do you have a boost gauge? Ifso, check to make sure you don't have a vac/boost leak. My LGT hasn't made anything that sounds like this, but the guys over at legacygt.com likely have seen something similar to this. Might want to pop in over there and see what they have to say.

 

[phucheneh]

It sounds like the issue might be that there's a turbo flat 4 under the hood.

Seriously, it just sounds like a turbo'd Subaru to me. I have a feeling it's going to be hard for any of us to pick up on any abnormal noise in that video- it may be a lot clearer to you since you drive it every day. Is it mixed in with the turbo whine/is the whine more than usual?

Is it a noise at WOT or just a noise at high RPM? I definitely didn't hear anything at lower revs. I don't hear any of the typical RPM-dependent sounds; doesn't sound like it has a turbo problem, or noise from an engine accessory or belt tensioner/idler. Doesn't sound like an input shaft bearing.

Boost leak seems likely. Whether it's vacuum or boost, air leaking in/out of the intake through a small opening can make a nice 'whirr' or whistle.

 

[TakeNoPrisoners]

Sounds like a turbo spooling to me.

 

[alkalinetaupehat]

That whirring noise sounds like a bearing, and since it's tightly correlated with your accessories, I'd check those first. Alternator, water pump, A/C, etc. Do they all spin freely?

 

[iamwiz82]

Sounds like the turbo to me as well, but you probably have a leak somewhere exasperating it. Have you changed the intake?

 

[JCH13]

Might be the turbo going out, as some have said. Subaru turbos seem to have a fairly definitely life of 130-140k miles.

Could be an intake leak, either boost or vacuum. Could even be an issue with the air filter.

The sound seems strongly correlated to throttle position, not so much engine RPM, so I don't think it's likely to be bearings, belts, or pulleys.

 

[jlee]

To go in a completely different direction...do you notice that sound on deceleration / downshifting? It's hard to tell with laptop speakers but I am wondering if it might be your differential whining a bit.

 

[alphatarget1]

To answer some of your questions: The noise was kind of faint that the phone didn't exactly pick up very well. When I floor it (WOT) the whirring noise develops between 4-5k RPM. I had a shop replace the intercooler last month with all new gaskets and the noise started happening a few weeks ago. The sound is only there at WOT.

I tightened the IC-turbo bolt a little bit. Will check back tomorrow to see if that helped.