I have a 1999 Jeep Wrangler. When I get over 35 miles an hour, and am accelerating or just keeping the same speed, I start hearing a "swishing sound" in the back of the vehicle. The faster I accelerate, the louder the sound. Could be the rear end gears or a wheel bearing?
When I push in the clutch, there is no sound at all, it goes away. If I push in the clutch, shift into neutral, and let up the clutch, there is also no noise, so it can't be the transmission i am hearing.
What can this be? The vehicle doesn't vibrate either from this issue.
I just had a mechanic test drive it and we replaced the real pinion seal which was leaking. I presume he made sure there wasn't a bearing going out.