Well, suddenly, I'm a little less sure I have a pinion bearing problem. I tried my little experiment of jacking up the rear of the car, and having someone "drive" it while I listened underneath. There are definitely noises coming from the transaxle (not a peep from the wheel bearings, though), but I'm not sure they're not normal. Whatever this sound is, it's much more noticeable inside the car than outside. My assistant's opinion is that what he was hearing wasn't anything he wouldn't have expected from a car with the interior aft of the seats gutted. He's a major car guy, so I trust his opinion.
So, I next confirmed the trans fluid was fully topped up (it is), put back the rear seat and cargo floor carpet/padding, and took it for a drive (it feels SO good to be able to finally say that). My reasoning was that everybody who has identified a pinion bearing problem has done it in a car with the interior fully intact, so I wanted to hear how it sounded in this "normal" condition. There is something that starts at about 35-40 mph, but I wouldn't say it sounds like a jet. It's more like a whistling sound a vacuum leak would make, and it even has some similarity to my car's shifter buzz, which I also always thought sounds like a vacuum leak, as odd as that may sound. Also, the sound level doesn't increase as I drive faster - I got it up to 80, and this particular sound is no louder than it is at 40. In fact, as road and wind noise increase, the SFKAPBD (Sound Formerly Known As Pinion Bearing Doom) becomes less noticeable, to the point that I can barely hear it. Also, the sound doesn't change in pitch or level as I let off the gas, or when I accelerate, which I thought was a characteristic of a pinion bearing issue. To tell you the truth, if I hadn't noticed it when the rear seat and cargo padding were out, and if the radio were working, I would never have noticed this particular sound.
I know it sounds like I'm trying to talk myself out of believing I need to have my pinion bearing replaced, but the symptoms don't seem to line up with the classic ones I've read about. Any ideas as to what else might make the type of whooshing sound from the back of the car that I'm hearing?
