Recently I've noticed an odd phenomenon with my stock '02 WRX; when I am driving 50 mph there is a loud humming sound, almost musical in nature, coming from the front of the car. The sound is like a whistling musical note -- it doesn't sound like grinding or friction of any kind, nor does it sound like tire hum.

The sound only happens at 50 MPH in 3rd or 4th gear (4th gear about 25k RPM is when it is loudest) and ONLY when I am on the gas; if I feather the pedal or release it entirely, the sound goes away. It is tough to localize the sound, but it sounds like it is coming from right on the other side of the firewall, although it could be the exhaust pipe under my seat. The sound is really loud -- I can hear it with the stock stereo turned past "7" in volume. Since I have a totally stock exhaust and turbo setup, a gasket leak seems unlikely, as does a bearing failure in the turbo -- what else could be causing the sound?

 

Manual or automatic? My first thoughts a failing clutch, o rmaybe a pipe leak. Does it get worse when you lay into the gas?

jason

 

Manual. I'm not certain it is a transmission sound, as my clutch does not slip (I know how to recognize that, I drove my two previous cars into the ground!) -- it gets louder on the gas and goes away off the gas, but it also goes away if I go past 55 mph. The sound ONLY appears between 48-52 MPH, period -- that's why it is so weird! If it is a drivetrain noise, how would I isolate that? I'm almost due for a tranny fluid change, should I just do that early and see if something is different?

 

Something could have come loose too. Could be a pipe joint leak, or a lose shield somewhere... things do just sometimes some come apart. At this point though that does sounds like a best case scenario. I can't really say much more w/o hearing it myself. Good luck though.

jason

 

OK, I tightened the bolts on my turbo heatshield; no difference. Bump for more educated guesses!