New noise like a roar or drone at higher speeds

Tyres? As they wear, their sound might change. Check for uneven wear patterns (fairly easy to see) which might be caused by bad alignment. hope this helps - Wil

 

Although it could be a transaxle issue surfacing, at your car's age and mileage I'd suspect one or both front wheel bearings. My daughter's '07 lost the passenger side at 140k and the driver side at 150. Diagnosing the passenger side was tricky as it was nearly impossible to tell which side the noise was coming from. When the driver's side went I just assumed it was not the passenger side again and this was correct.

If you "'slalom" the car from side to side, does it make the noise louder with regard to which direction you're swerving? Popular opinion among mechanics is that the bad bearing will be opposite the direction which makes the noise louder. In my case it was just the opposite, swerving to the right was loudest and it was the passenger side bearing that was bad. I was able to make the call by having my wife drive so I could compare the noise I was hearing from both sides of the passenger compartment. Raising the front end and spinning the wheels in neutral was no help and there was no "play" in either wheel when lifted off the ground. It's really a bit of a crap shoot to diagnose. Knowing what I know now, and at your mileage, I'd just do them both.

The Timken HA590064 is likely the OEM Koyo bearing and can be had for $101 on Amazon if you're DIY. This is the bearing I used. Toyota dealer will want $700-$1000 to do both. Perhaps a good independent mechanic will meet in the middle but I'd require the Toyota factory part or the shown Timken.

 

A good mechanic should be able to properly diagnose this. My guess is a front wheel bearing, or both fronts. I've seen these go at around 180k. If it's a northern car they can go much earlier. We've used Moog bearings with good results. They run around $100 at Advance Auto Parts after using online discount codes. Labor shouldn't be too bad, maybe an hour or two.

 

Wheel bearing. The noise is transmitted through the drivetrain and can sound like it is coming from elsewhere.

 

I hope that it is a wheel bearing (failures have been noted in Prii before), but if the turns out to be not the cause, another suspect is a shorted turn in one of the MG coils (part of the transmission). You can read up on this failure on Luscious Garage | Hybrid Specialists. A link to their video on "MG2 repair" is at: VIDEO - Prius P3125, P3009, P3120 - MG2 repair - Luscious Garage | Hybrid Specialists. Did you ever drain and refill the ATF (Toyota Type WS)?

JeffD

 

How's your musical ear? Do you have a sense for what pitch the drone is at a given speed (or can you use a cheap tuner app on your phone for that)?

The first time I had a wheel bearing go, I was concerned about the possibility it could be the transaxle, until I worked out that the pitch wasn't related to any whole-number multiple of the transaxle MG2 rpms, and that relaxed me about the major worry so I could just look more calmly for the real problem.

A few years later when I had a front bearing go, I heard a characteristic pitch from it too, different from the rear (but I have a Gen 1, where front at rear bearings are quite different styles; the exact details may be different for your Gen 2, because it uses the same type of bearing front and rear, though the sizes might be different).

-Chap

 

Yes tires and wheel bearings are first to check.

 

While having the wheel bearing fixed drain and refill the ATF with Toyota type WS ATF (~$10 per qt - you need 4 and 2 crush rings). My Toyota dealer charges $100, but it is a straight forward DIY (see: ATF fluid changes ARE Required. | Page 27 | PriusChat). Capture a few ounces of the used ATF in a clean Poly bottle so you can send it in to R&G Laboratories, Inc. - Home for analysis (~$25) and report the results on PC.

JeffD

 

Please can you let me know how it goes? - I have the same problem....(not tires...)

 

FYI, sad to say but the OP hasn't been back to give us any verification since posting this over a year ago.

 

I love this forum: I've been having the same issue for a few years now (in my own 2007 Toyota Prius) - i think, left unchecked, I ended up having to repair the drive shaft (something with the rack and pinion - very expensive). While I'm down there, I'm going to have them check the rotors, too, as the last time I had them checked there was at least surface-level rust. Concerned that at high speeds it might cause some additional wobble or shaking (something I looked up when attempting to ascertain this issue).