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Funny Noise Coming Under Hood

Discussion in 'Gen 2 Prius Technical Discussion' started by John6012, Dec 20, 2008.

  1. John6012

    John6012 Member

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    I have an 07 Prius and for sometimes on occasion I hear a whoo -whoo sound when moving and sitting at idle with the engine off. I wonder if anyone else has this problem? I'm going to take it in for the 15,000 mile oil change and mention this but if it doesn't make the noise, the dealer can't isolate or "fix" whatever it is. I had a Nissan once and took it into the dealer and they couldn't find the problem and they said as long as I tried to report it and have it repaired, it would be covered a couple years down the road. Anyone ever hear of this? It'd be nice to take the Prius in and if they couldn't find the problem it'd be covered later....but right now does anyone have a similar whoo-whoo sound under the hood?:(:confused:
     
  2. paprius4030

    paprius4030 My first Prius

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    The Prius makes alot of different noises, the most notable is the theromos bottle being filled but you notice this the most when the car as be turned off, not if your sitting at say a red light with the car in the ready mode. If everything is working all right I wouldn't worry about it.
     
  3. Rokeby

    Rokeby Member

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    Probably not a problem.

    The "Energy" screen on the MFD shows energy movement (above some
    threshold value) and not ICE, the engine, status. So unless you're
    monitiring RPMs on a ScanGauge or something, it can at times be difficult
    to determine whether the ICE is or is not running.

    That said, can the occurance be isolated to:
    cold vs. hot days
    wet vs. dry days
    ICE cold vs. warmed up
    A/C on vs. off

    Unlikely sources, but have you checked the radiator fan/serpentine belt?

    You don't say where you're from. Maybe you have a saw whet (sp?) owl
    caught under the hood/bonnet. :rolleyes:
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi John,

    Are you familiar with the sound that the brake pressure accumulator pump makes? If not, depress the brake pedal repeatedly while the Prius is READY, to force the pump to run. That sound is normal.

    If the sound that you reported above is different than the sound made by the brake pressure accumulator pump, then please let us know.
     
  5. leafcar

    leafcar Junior Member

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    Did you ever resolve this? If so, what was the cause? I have the same exact sound you describe and will be taking it in for service next week.
     
  6. Evilshin

    Evilshin Member

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    I assume you mean that whirring sound. That would be the coolant pump that fills the thermos bottle (to quickly rewarm the engine when it does need to get started).

    If you shut off the car after driving for a while and you hear that noise after shutting down, then it's the coolant pump.

    Either that or you have Arsenio Hall hiding under your hood... ;)
     
  7. leafcar

    leafcar Junior Member

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    It's definitely not a whirring sound, it's a woo-woo-woo as in Curly from the Three Stooges kind of sound. Very different from the thermos sound, and this happens when the car is stopped but in Ready mode.
     
  8. Evilshin

    Evilshin Member

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    Are you hearing it, in place of the thermos sound? If so check your coolant levels... the woo woo, might be the pump dry heaving...

    If adding coolant doesn't help, maybe it's time to have a certified tech look at it...
     
  9. leafcar

    leafcar Junior Member

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    No, the thermos sounds fine. I'm almost certain it's related to climate control since it goes away when climate control is turned off.

    The talk about hearing it when stopped is a red herring. It's a low sound and when the car is moving it's drowned out by road noise.
     
  10. justlurkin

    justlurkin Señor Member

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    I have an '07 and I also hear that "whoosh" sound in addition to the ratcheting thermos coolant pump sound.

    I've heard both of those sounds since the day I got my car back in '07 and it was never a problem for the past 2 years, so I'm sure they are normal.

    I sure would like to know what's making that whoosh sound though!
     
  11. Evilshin

    Evilshin Member

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    Do you have your A/C or front defrosters on when you hear the noise?
     
  12. leafcar

    leafcar Junior Member

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    Yes to the A/C, no to the front defroster.
     
  13. Evilshin

    Evilshin Member

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    Does it make the same noise if the A/C is off? (Front defroster off too.)

    If not, then it might be the compressor.