1997 Subaru Legacy 4 cyl All Wheel Drive Automatic 170000 miles
I have a 1997 Subaru Legacy L AWD, at 170,000 miles. When I first got it, about a year ago, it has a strange slight winding/whistling noise from under the engine. The sound has pitch relating to the speed, and is pretty constant, changing slightly between acceleration/coasting.
Starting about 5 months ago, the winding noise has developed into clunking sound. In addition to noise, the car started to vibrate as well. The heaviest vibration is under lower speed, below 30 MPH. It felt as if there is a gear tooth broken or something like that.
Then recently, the noise has developed even worse, closer to screeching/screaming, like metal scratched on asphalt. Beginning from stop, as the car accelerates slowly, there is a knocking rhythm in some parts of the gear down there on the front, getting faster and faster according to speed, then it begins to screech. The whole car is vibrating according to the rhythm as well, pretty violently. The faster the car goes, the vibration is reduced. Think of a rotor with one or two spokes missing, at low speed its wobbling around but at higher speed its a little bit more stabilized, although still vibrating.
As my car is AWD, I tried to turn off AWD by plugging a fuse just to see how it goes. After the car becomes FWD, these noise and vibration only happens during acceleration. Coasting is completely smooth. As soon as I hit the gas pedal even slightly, the noise and vibration returns. The noise and vibration are also more prominent when little power is produced, for example, when climbing a slope, the noise is somewhat dampened. When going down a slope while applying gas, it seems to screech more. Again as soon as I release the gas, it does not make any noise/vibration, similar to when I put the car to neutral.
I know the car is pretty old and high mileage, but as I’m in a pretty bad financial situation, I would like to know if I can fix this problem as cheaply as possible, or if I should just leave the car in the dumpster.