I've noticed about the last 4 weeks my 2008 touring Prius (85k miles) seems be running louder than it always used to. There is a sort of humming noise that follows the speed of the car, whether the engine is running or not, in neutral or drive. No warning indicators on the dash. No change in mileage observed. Seems slower to accelerate too, though I'm not entirely sure. Any thoughts? I'll probably bring it in to get checked. Extended warranty runs out soon.
Wheel bearing? Water pump? Inverter coolant pump? Does it make the noise when in Ready but stationary?
Wheel bearing problems have been seen here often enough. Does the sound change if you corner sharply at speed one way or the other? Have you changed the transaxle fluid? If not, then now is the time.
"Any thoughts? I'll probably bring it in to get checked. Extended warranty runs out soon." Just do it...Service is open half day on Saturday.
There is no noise until I get up to at least 30 or 40 mph. Definitely not related to the ICE. Driving on a twisty road, the noise seems to get a bit louder turning right and goes away turning left. If I didn't know what my car usually sounds like I probably wouldn't notice. Wheel bearing sounds like a possibility, after searching about that here. I have an appointment with the dealer next week. Is there a great risk driving the car until then? thanks. Transaxle fluid has not been replaced. I'm understanding now thats recommended here in addition to Toyota's scheduled maintanance?
With the wheel jacked off the ground, grasp the tire and try to vigorously wiggle it back and forth. Any play or looseness would indicate a worn bearing. Let the service guy know if you do find such. I would not plan on any long trips at speed in that condition. Yes, change the transaxle ATF, based on the used ATF analysis reports that have been posted here. Once you see the old stuff come out, you will be surprised.
To some degree, YES. I personally would not want to go far, nor would I want to go fast. You do not want a wheel bearing failing on you at 80 mph! Actually, you wouldn't want one failing on you at 40 mph. You may probably be ok depending on how long ago and how severe the noise is. It's your decision!
Dealer replaced the left front wheel bearing under warranty. I checked the hub wasn't getting hot when I had to drive yesterday, but it definitely was getting louder. After the repair they found the left side was drowning out the right side, so they need to order parts and replace the right front bearing tomorrow. I asked about replacing the transaxle fluid, their hydrid tech did not recommend as needed based on Toyota, but they would do for about $160. Sounds like something a handy person can do themselves.
I don't know why Toyota has such a questionable policy, but data here indicates it's good to change it. It is DIY easy, but you will need to get the car off the ground enough to get under and undo the drain and fill plugs. That means ramps or jack stands. Any mechanic can also do it, and for much less than $160. Sheesh.
You should also get a pair of the proper crush washers for the fill and drain ports. It is a good idea to loosen the fill port before opening the drain port. Jeffd
