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Transmission noise

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by woodenpaddler, Mar 23, 2013.

  1. woodenpaddler

    woodenpaddler Junior Member

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    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.
     
  2. GrumpyCabbie

    GrumpyCabbie Senior Member

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    Wheel bearing? Water pump? Inverter coolant pump? Does it make the noise when in Ready but stationary?
     
  3. nh7o

    nh7o Off grid since 1980

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    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.
     
  4. frodoz737

    frodoz737 Top Wrench

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    "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.
     
  5. woodenpaddler

    woodenpaddler Junior Member

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    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?
     
  6. frodoz737

    frodoz737 Top Wrench

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    Shouldn't if you take it easy on her. Just don't delay your scheduled visit. ;)
     
  7. HaroldW

    HaroldW Active Member

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    Could be a tire as well. Alignment problem causing cupping of one of the tires. h
     
  8. nh7o

    nh7o Off grid since 1980

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    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.
     
  9. GrumpyCabbie

    GrumpyCabbie Senior Member

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    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!
     
  10. woodenpaddler

    woodenpaddler Junior Member

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    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.
     
  11. HaroldW

    HaroldW Active Member

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    Yes it is strait drain and fill with 4 qts. Make sure you use the oil Toyota recommend. H
     
  12. frodoz737

    frodoz737 Top Wrench

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    Good to hear woodenpaddler. It is best to always change the wheel bearings in pairs.
     
  13. ahmeow

    ahmeow Prius Lover

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    OK I've learn something. Need to pay attention. Thanks for everybody.
     
  14. nh7o

    nh7o Off grid since 1980

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    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.
     
  15. jdenenberg

    jdenenberg EE Professor

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    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
     
  16. lokareddy

    lokareddy Junior Member

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    after replacing front wheel bearings did it run smoothly?
     
  17. jerrymildred

    jerrymildred Senior Member

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    Four year old post. Original poster was last seen here over 3-1/2 years ago.