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Aerodynamic Anomaly?

Discussion in 'Gen 2 Prius Main Forum' started by TonyPSchaefer, Jul 18, 2008.

  1. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    Priapus seems to have picked up a noise like air being disrupted. It reminds me of when I'm riding in a friend's car with the canoe rack mounted.

    I've checked all over and can't find anything out of place. There's nothing to hear until I reach 40 mph. At that speed, it's constant. At 55 mph, it is pulsing. It starts with nothing, increases in noise, then decreases to nothing again. By my count, it's one second increasing, one second decreasing, and one second quiet. But only at 55 mph. I actually have not exceeded 55 mph since hearing it so I can not report on faster speeds.

    As I was washing him last weekend, I noticed that the spoiler seemed a little looser than I remember. Nothing overly alarming, but I seemed to be able to wiggle it up and down more than I remember being able to. Not that I try often.

    Another item for consideration is that I am due for new tires. I'm still running stock tires after about 47,500 miles.

    Thoughts?
     
    #1 TonyPSchaefer, Jul 18, 2008
  2. Rokeby

    Rokeby Member

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    Did you check up under the chassis?

    It's possible that you have a plastic bag or other road debris stuck on
    something under there.

    Loose mud flap or tire air dam?

    [Edit] There are a few plastic belly pan pieces under there too. Perhaps one is
    torn and has a flap hanging down into the air stream.
     
    #2 Rokeby, Jul 18, 2008
  3. nerfer

    nerfer A young senior member

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    Rokeby might be onto something. But you might need a helpful friend to hang over the front of your car looking underneath as you increase speed. Above 40 mph your friend should be able to easily spot the problem.

    (I am not a helpful friend).
     
    #3 nerfer, Jul 18, 2008
  4. Sheepdog

    Sheepdog C'Mere Sheepie!

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    "(I am not a helpful friend)."

    LOL! At 40mph who would be?!
     
    #4 Sheepdog, Jul 18, 2008
  5. finiyon

    finiyon Re-Member

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    If the sound is coming from the rear and you think that the spoiler may be loose, try some blue painters tape at the base of the spoiler. For a few cents you can eliminate one (of many) possibilities.
     
    #5 finiyon, Jul 18, 2008
  6. seasalsa

    seasalsa Active Member

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    Tony, you failed to mention if the windows are open or closed! I get the pulsing when I forget to close one of the rear windows.
     
    #6 seasalsa, Jul 18, 2008
  7. Highly ImPriused

    Highly ImPriused Impressive Member

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    Could it be the cargo area cover? I notice that tends to rattle a bit at times.
     
    #7 Highly ImPriused, Jul 18, 2008
  8. fcc

    fcc New Member

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    i noticed that the other day and was rather disappointed. pulsing is a kind
    word to describe the most annoying sound i ever encountered with a back window
    down.
     
    #8 fcc, Jul 18, 2008
  9. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    You are correct, I failed to mention that!

    It's been almost a week since I started hear the noise. Of course, I didn't want to start a thread and then find out that it's something simple like the gas lid was open. So as I mentioned, I have spent the week looking, listening, trying to pinpoint what it might be.

    Usually when I'm moving at all, the windows are about one inch cracked and when I'm above 50 mph they are all the way up. I have heard it regardless of window position.

    It does sound as though it's coming from the back. If I had to pick a side, I'd say back passenger side.
     
    #9 TonyPSchaefer, Jul 18, 2008
  10. Sufferin' Prius Envy

    Sufferin' Prius Envy Platinum Member

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    Have you considered an out of round tire? The noise is speed related, and you can sometimes get a pulsating sound from the tires. And if it is a rear tire, you won't necessarily feel it like you would a front tire.
     
    #10 Sufferin' Prius Envy, Jul 19, 2008
  11. RonH

    RonH Member

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    Although you won't get a friend to sit on the car hood, he'd mess up the stream lines anyway, it might be worth while to drive by one at speed to see if he can identify the location of the noise. Even forward vs aft vs underneath would be helpful. Being inside can lead to tricky acoustic paths which might fool you. I've successfully tracked down bearing noises that I couldn't identify inside the car that way.
     
    #11 RonH, Jul 19, 2008
  12. hyo silver

    hyo silver Awaaaaay

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    You had to go and wash Priapus without mutually beneficial assistance, that's the problem. I'll bet the integrity of the transverse subsonic inhibitors has been compromised.

    Either that, or the tape over the screw holes under the side view mirrors fell off. ;)

    And you're gonna need glasses if you keep this up.
     
    #12 hyo silver, Jul 19, 2008
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