I have a 2001 w/94k. New tires and alignment (3k). Recently I have been hearing a humming noise which can start to be heard around 45mph which gets increasingly loud up to 65mph, and then seems to quiet down if I go above 70mph. From the driver's seat it sounds like it's coming from the driver's side rear of the car and from the passenger seat it sounds like it's coming from the passenger side rear of the car. So it definitely sounds like it's coming from the rear of the car. Bringing my car in to get looked at it is difficult with my work schedule, so I thought I would try here first. Around the city there is no noticeable sound and there has been no loss in MPG that I can tell (44-47). Thanks in advance.
Several things can cause a hum: after a drive - walk around the car and feel each hub to see if one is hotter than the others. A failing wheel bearing will often heat that particular hub. Be careful as we measured 150F on one a month ago and this is uncomfortably hot. get a Prius aware scanner - one that can report MG1 and MG2 temperature. A failing stator, one with a burned coil, will cause MG2 to run hotter than MG1 and the engine coolant temperature. But you need a Prius aware scanner to read out these values. Bob Wilson
Sounds like there's a decent chance a rear wheel bearing will take care of it. (You can read back earlier in that thread for some ideas on how to make sure it's a bearing and not something else, or how to know which wheel.) -Chap
question, was this noise heard after replacing the tires. some tires can make noise from the tread. you can try to rotate the tires. put the front on the back and the back on the front. see if the noise stays or moves.
Thanks guys! It was the right rear. The other one seems to be fine. I just ordered the Timken rear hub assembly from PartsGeek for $186, free shipping. I let you know have to use any tricks getting the old one off...
I'm installing a Timken rear assembly on my 2001 tomorrow. Can any of you tell me the torque specs for the job?
Any update on this? I am having the same exact issue. Humming noise and vibration around 45-55mph then goes away almost completely at 70mph or higher. Did changing the rear assembly eliminate the issue? You had said that prior to this you had gotten new tires. Did those tires happen to be Goodyear tires?
It was in fact a failing wheel bearing. It took my Dad and I the better part of an afternoon to get the old assembly off. I'm guessing partly due to it being a New England car, the rust has essentially fused the metal together. After trying multiple slide hammers and an array of sprays, what finally got it off was big swings with a 20lb sledgehammer while my dad held a thick piece of wood in front of the wheel. Timken rear assembly looked like a nice product when it arrived and I haven't had any problems since.
Just realized you have a 2012 Prius, not 2002. Your bearings shouldn't be failing yet but if that is what is wrong you shouldn't have any issues getting the old assembly off.
