[mudhead]

Long story short, Got a flat tire while driving, tried to make it to the shop before it went completely flat. Ended up driving at freeway speeds for a mile with the driver front tire almost completely flat. I stopped before any damage was done to the tire. Probably should have stopped when I noticed the leak. Anyway, pulled over and put the spare on. Slowly crawled back home. Took tire off, got it fixed. Now there seems to be a noise coming from what I assume is the front differential and gets louder with an increase in speed or acceleration. If I get up to speed and let off the gas, the noise goes away. This is on a 2006 Forester X with the auto tranny. I have changed the front differential fluid, which is separate from the transmission fluid and that helped slightly. Is the front differential muffed or is it something else?

 

[RyanT]

Could be your centre diff / viscous coupling. Running on a flat is effectively the same as running on a tire of the wrong diameter. This is really hard on the viscous coupling in the subaru AWD.

Change your transmission fluid. If it comes out sickly black and slippery like silicone, you've pooched the coupling.

 

[mudhead]

Is there anything else I can check while I'm down there? Also, would a bad center diff only make noise when under load like accelerating or going up a hill along with not demonstrate any shaking when turning or whatnot?