Growling sound while driving

Change the transmission fluid with Toyota Original .. you can buy from local dealer or shop online..

The growling with wheel bearing usually changes "tone" with slight change in gas.

Tires, are they good? Tires, especially winter tires can make noise

 

There's no separation inside the case; it's all the same fluid.

 

If there's no sound in the air with the car in gear; WHY do you think it's the transmission/transaxle???????????? Isn't it spinning when you had the car in gear in the air???????
I've had bad wheel bearings that didn't present themselves until you loosened the half-shaft and what about the rear axles. You running that Prius on only two wheels??????

If you loosen that half-shaft nut and push it back 1/4 inch; your wheel will wobble if that bearing is gone. The hub will also heat up, due to all the friction. Don't wait too long cause things will start wielding together.

 

Wheel bearings usually present noise loaded with weight . In air almost nothing . Now take stehscope whilst spinning carefully listen to bearing housing rt at axle penetration . You hear the balls moving round scrape scrape etc . Pull it out of ears ya hear nada .

 

I'm with Mr. saneesh8 here; check your tires first. I had a 2001 Saturn that I would have sworn had a failing wheel bearing RH side; classic growling sound that changed pitch with speed. No play or noise in the bearing when jacked up, same as OP here. My neighbor suggested I swap the front tires L-R and drive the car... Bingo, noise switched to the left side. Replaced that tire, no more noise. Turns out that certain tires will do that from wear. Saved me a bunch of grief not to mention $$. You might give that a shot; nothing to lose except a few excess calories lol. Good luck!

 

Wheel bearing.

 

You can see from my old how to tell which wheel bearing? thread that sometimes it's really hard. All the different rules of thumb people usually suggest were falling flat, and I had to go get my hands on a ChassisEar before I could actually be sure which bearing it was.

On the bright side, once the ChassisEar was hooked up, picking out the bad bearing took like three seconds.

 

I wouldn't put anything but the Toyota WS in it. That's a totally different transmission/transaxle than other automatic transmissions. It doesn't have the friction surfaces like what's been used before. Don't mess with what works. Go to the dealer and get what you need. If someone put something else in it, get enough to flush that out of your car too.

Does the noise change with the speed? Does it change when your turning left, turning right? Can you get someone to drive by you so you can listen for which corner of the car the noise is coming from?

I also lost a wheel bearing and it didn't make any noise. The way I found out that I had a bearing problem was that the tires were cupping. I jacked up the car and wiggled the tire side to side, then up and down. Side to side is likely to be a tie rod problem; up and down is likely to be a ball joint. I did get the excess play, but when I looked at what was wiggling, it wasn't either. It was the wheel bearing.

Could it be a corroded/bent dust cover? One of the plastic underbody panels or wheel liners that's tangled up on something or dragging?

 

Cupping can be worn out shocks, wheel bouncing up and down rapidly.

The reason you need to back-off the spindle nut is because the wheel bearing is sandwiched against the wheel hub. You won't find "play" unless that bearing has be howling for a good long while, and is totally destroyed. If the bearing is in the early stages of going bad; you'll find wiggle, once you back-off and push the shaft back a little. If the bearing is fine, there won't be any "play" - it'll be as solid as the tight spindle nut.

FWIW: this also works on 4wd too. A guy on YouTube actually removed one of his front half-shaft on his 4x4 to figure out which bearing/hub was bad. It was a newer auto-locker, so a bit expensive on the replacement. I guess that's what you have to do, when you don't know any better....