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Ryhthmic Brake noise? Heat shield?

Discussion in 'Prius v Main Forum' started by Capecodbeachfront, Jul 23, 2020.

  1. Capecodbeachfront

    Capecodbeachfront Junior Member

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    2013 Prius V with 80k miles....
    I am again getting a rhythmic front brake noise (thump) while gently braking...
    Last time I was told rust ridge which was sanded away...
    I feel no odd vibrations thru the pedal...
    If I brake just a tiny bit harder the thumping goes away?
    I did just replace tires so I thought 'bad belt'?
    But with no obvious signs or shake or pull on the wheel I doubt it is tires.
    So I am back to suspecting brakes? Is the rust ridge theory real or dealer BS?
    Can I eyeball it and see rust?
    Would some extremely hard braking 60 to 0 maybe clear it?
    ALSO
    At start up I have a rattle that lasts a short while...
    Is there a heat shield located between the dash and engine compartment?
    Definitely a rattle, ICE related,
    Dealer said they checked all heat shields and found none loose...
    But if there is one between dash & engine I bet they could not check easily?
     
  2. rjparker

    rjparker Tu Humilde Sirviente

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    You are unlikely to feel a bad rotor through the pedal because its brake by wire. Even then, the hydraulic brakes may only be used at very low speeds under gentle braking. Hard braking will apply the hydraulics at speed. But its possible that frequent hard braking could have warped the rotors. Have somebody check the rotors for warping. If bad, you have to buy new rotors. However my v has 240k and still has factory pads and rotors because of regen and reasonable braking most of the time.

    I would bleed the brakes using “invalid” mode or Techstream. If the problems go away great, if they come back in a day or two there could be a brake booster pump or master cylinder problem.

    Rattles at startup usually means the engine is not synchronizing with the electric motors in order to make the planetary gears work. There is a mechanical clutch like assembly in the transaxle that is always engaged but will slip under sync failure modes. Its possible that ignition or fuel is causing it but those problems usually continue. Pcv feeding oil into the intake can do it, as well as a failing head gasket. Its also possible to get engine knocking with regular gas, a carboned up engine and low hv battery charge. Try a tank of high octane to see if this is the case.
     
    #2 rjparker, Jul 24, 2020
    Last edited: Jul 24, 2020
  3. Tim Jones

    Tim Jones Senior Member

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    Better trade it in before the really bad stuff happens.....
     
  4. rjparker

    rjparker Tu Humilde Sirviente

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    Probably not bad advice if you can get close to Blue Book for it. Besides anyone on Cape Cod Beachfront probably should be driving a late model Lexus.
     
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  5. Air_Boss

    Air_Boss Senior Member

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    Late model Lexus 4WD, that never leaves the pavement.
     
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  6. Raytheeagle

    Raytheeagle Senior Member

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    The oversized rims give that away:p.

    If not that, I'm pretty sure in the owners manual somewhere I read in our 2017 RX that they recommend not taking it off the engineered surfaces:cool:.

    With how thin the paint is, I'm not sure I'd want to anyway(y).
     
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  7. Kenny94945

    Kenny94945 Active Member

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    Rust edge...I don't think that is your issue.
    Wear edge could be.

    Was the issue there before your new tires?

    I'd guess the first step is to visually inspect the rotors, are they smooth?
    If not, a rotor change or machining could resolve the issue.
    If smooth, could be a glaze build up on the rotors, do a 'net search how to de-glaze.
    Also, cleanliness of you calipers is a good thing, so remove all the brake dust from the rim barrels and the caliper pistons etc.
    Further, reapply brake grease to the pins and pads (as the service manual specifies) is a good thing.
    Lastly, I have read the pins have wear issues, so an inspection and replacement could be "called for".

    Yes, I would do the hard braking bedding procedure. (75 mph to 45 mph engaging abs - six or so times taking care to cool the rotors between each hard stop).

    I have no two cent comment on your rattle.
    Rattle searching can be a trying experience.

    Good luck.
     
  8. Tim Jones

    Tim Jones Senior Member

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    Great info! Seems like pretty low miles for wear problems.. I wonder if this could be corrosion related... never really see any here in south east texas.
     
  9. Capecodbeachfront

    Capecodbeachfront Junior Member

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    Back 3 months ago I was getting brake and traction codes. Tires were worn and the service writer said to replace tires when they found no reason for codes. At the time the consensus was it was silly advice... Well within days after replacing tires the codes went away and have not been back! The thumping has come after tires were replaced. Most noticeable at very low speeds and gentle braking. Has the same sound you get when going over road cracks that have been repaired with brush on asphalt.... stripes running across the road.
    The rattle is not the engine knock (shake) you get when ICE has been run briefly and shut off after only a few seconds during the winter. This Really does sound like a shield but higher up on engine in front of dash? Does not last long enough to accurately locate.... Last tech said he could hear a rattle in manifold but not loud enough to be heard inside car. I think he might have been just appeasing me, rather than saying I was hearing things.
     
  10. Tim Jones

    Tim Jones Senior Member

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    Have you rotated the tires?
     
  11. Capecodbeachfront

    Capecodbeachfront Junior Member

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    New tires have less than 2000 miles on them. Reputable dealer so I trust they were balance correctly. No vibration thru steering... Just thump, thump when braking lightly. I Will check inflation?
     
  12. Tim Jones

    Tim Jones Senior Member

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    I had a brand new Mich that was bad.... pulled.....I couldn't believe it was the tire but I put the front on back and the pull was gone.
     
  13. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    Ask the tire place to road check with you. Or maybe for you given the situation currently. When was the last time the car's alignment was checked? Seeing you live in the NE area where roads can be .....
     
  14. Capecodbeachfront

    Capecodbeachfront Junior Member

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    Just back from my latest visit to Toyota Dealer. For $115 I got the same run around. "Unable to duplicate the trouble sound" and replaced missing nut on heat shield. Sound was of course still there on my way home. Suggested options: Rotate tires (at 1500 miles?) I might actually do the front / back switch suggested earlier on this thread to eliminate tires as source. As a crazy option... I also looked at the plastic wheel covers. They do have a flex... could they be the source of the thump? I was able to make them flex in and out actually touching inner wheel. I was thinking of pulling the plastic covers before doing the front/ back tire swap. Troubleshoot one option at a time. Do I need center hub covers if I do this? Never knew until this latest research that there were good looking wheels hidden under the plastic covers! Bottomline, for $115 I at least know the brakes are good which is reassuring. Thank you for your suggestions....
     
  15. Tim Jones

    Tim Jones Senior Member

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    I took the hubcaps off soon after i got the v. Bought center caps online.