wheel bearing

Turning left loads the right side of the car, so yes. Left turn noise = right side problem. The classic wheel bearing noise is that of a small airplane. If it reliably appears on left turn and diminishes/disappears straight or right, then wheel bearing is a good bet, though CV joint is also a possibility. A bad wheel bearing will sound more like a small airplane. A bad CV joint often sounds more like popcorn going off.

If you want to decide the difference, drive very slowly in a left-hand circle. At slow speeds a bad CV joint is likely to still go pop pop pop, while a bad wheel bearing will likely make no noise or maybe more or just a whirr or faint chafing sound.

Unfortunately, I am going on general knowledge rather than Prius-specific, so things might be different because of this car's weird transmission. But if you jack it up and put it in neutral and spin the front wheels a bad wheel bearing should be easily detectable by grinding noises.

As far as changing one ... no clue. I'll figure out how to cross that bridge when I come to it.

 

If the noise changes with turn it's bad bearing. Normally it's that noise when turning left is bad right bearing. But not all the time. So test by jacking and feeling the bearings.

Bearings are hub assemblies. If they salt the roads there then front bearing will rust to the knuckle and you might have to take the knuckle with bearing, backing plate, ball joint, and maybe abs sensor to press to get the old one out. If you don't have a press or maybe big air hammer you would need at least knuckle, bearing, and backing plate to make it easier.

 

If I remember right, I took the front knuckle out of mine and dropped it off at the friendly local auto parts and machine shop place, along with a new hub bearing and snap ring, and picked it up when they phoned and said it was done.

The posts about beating with a hammer are probably about the rear hubs, or front and rear on Gen 2 or later. Those are bolt-on (and sometimes hammer-off, if the corrosion is bad).

Front bearings in a Gen 1 are different, they are not bolt-on to begin with, but pressed in. As a saving grace, I think the Gen 1 knuckle isn't aluminum, but the hub will still be very happy right where it is after so many years. The machine shop charged me maybe $30 for the work, which seemed fair when I picked it up and saw the evidence of mighty doings.

I don't know what car you're talking about here, as your profile says Gen 1 but the forum is Gen 2.

 

You're in the right place

 

Yes. It's weird, but Gen 1 seems to just be some kind of "sub-forum" under gen 2. It was confusing to me when I first got here.

 

I'm pretty sure it looked like it was just in Gen 2 this morning, but maybe I was crosseyed.

 

I hope its ok to revive this existing thread, the topic fits perfectly.

My 2004 P2 makes a high pitched sound in slight right turns. I wouldn't at all describe it as a small airplane though. Could this be a wheel bearing?

 

You landed in the Gen 1 subforum, whereas yours is a Gen 2. So you might be better off creating your own thread in the Gen 2 forum.

That said, if it is high-pitched I often think first of brake pad wear warning tabs (although IDK if the Prius pads have these as I haven't had to mess with my brakes) - a little pc of metal that sticks off the pad and when the pad gets low it rubs on the rotor and tends to make a god-awful high pitched sound. (This gets people to the shop). It can often start by just showing up sometimes and under certain conditions (like turning) which just means it's still early on but getting close. More often than not, you can stop this sound by applying the brakes. So it makes noise at you when just driving along and tends to go away when you brake. So try that - safe place like a parking lot. Stay at low speed. Do whatever to get it noisy and apply the brakes.

This will not tell you anything 100% - car has to go up in the air and get inspected.

 

Wow, i searched the P2 forums for "bearing" in thread titles, and ended up in the P1 forum sorry.


Thanks for the suggestion, but it can't be the brakes: i replaced discs and pads on the front axle last year, they have like 10000 miles on them.

 

Not a big deal - confusing here because the Gen 1 stuff is in some weird "sub-forum" or something under Gen 2.

In any case, another thing that can do this is a bent/broken dust shield behind the rotor.

Though yeah, it's also possible that a wheel bearing noise can be high pitched. I've always gotten more like growl/rumble - like a small plane. But if can come out in other ways. The real "tell" on a wheel bearing us usually that the noise stops turning one way and starts or gets worse (if it's already there going straight) turning another. It depends on what side of the car is being loaded. A left turn loads the right side so noise that appears/gets worse turning left indicates a right side problem and vice versa. Most of my bad ones in the past have also varied with speed, often with no noise at lower speeds and loudest in the 45-55mph range.

Oddly it can even depend on temps too, especially if there's been some seal leakage. Colder grease doesn't flow/lube as well so I once had one that in the early stages of failure would only be noisy when cold...

The real way to check is to jack up the car. Grasp the wheel side to side, wiggle back and forth and see if there is any play. There should be zero. Spin the wheel and listen for any sounds of roughness or such.

 

Now that you mention it.... the dust shields are bent a little here and there on both front wheels! I actually had to bend one out of the way a little for the disc/pad replacement! That might just be it. I had completely forgotten about that dust shield.

OK, so dust shield check and wiggle test it is. Front left wheel first as the noise is noticeable in right turns.
Thanks for the advice!