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First timer, '07 Pkg 4, 15 Days and counting, Strange noise

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by N7OKN, May 2, 2014.

  1. N7OKN

    N7OKN Junior Member

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    Hi John here.
    I picked up my first Prius, an 07 pkg4 with 103K salvage title.

    During driving, and lasting about 5 minutes after the car is turned off, a pump sound is heard for about 8 seconds, then off about 20 seconds or so, then on again for 8 seconds. It sounds just like the air pump on the leveling shocks on my '02 Chevy Venture van. It's the sound of a small piston pump, not the whir of the coolant pump. It doesn't seem to affect the drivability or performance, it's just odd as I don't remember hearing that on any of the test drives of other Prii.

    It also starts in with it when I simply unlock it and open the door. Then for 5 minutes or so it keeps it up till it's convinced no one is around. I sometimes think it's as if it's purring when it senses humans. Does anyone have an idea what this pump could be? There are other oddities and questions I have, but I would rather keep one topic per thread.

    I really love my new (to me) car.
     
    #1 N7OKN, May 2, 2014
  2. JC91006

    JC91006 Senior Member

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    It's unfortunate you bought a salvage vehicle, depending on how well it's repaired, it could be a great car or a complete nightmare.

    The sound you are hearing is normal. All of our cars have it. It's just the brake actuator pump. You'll hear the same sound if you pump your brakes a few times while in park. So far this isn't an issue with your salvage car.
     
    #2 JC91006, May 2, 2014
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  3. N7OKN

    N7OKN Junior Member

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    Thank you. I just didn't remember hearing it start up with other Prii with just opening the door to get in with the car off. I can rest easier now.
     
    #3 N7OKN, May 2, 2014
  4. JC91006

    JC91006 Senior Member

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    the sound is a normal sound, the frequency or duration of the sound may be in question. I'm not fully understanding when you are hearing these sounds.

    If you hear the sounds often, it could be a sign the pump is weak and not holding pressure. A DTC will be logged by the car's ECU if it detects any abnormality. At that time, maybe a replacement will be needed
     
    #4 JC91006, May 2, 2014
  5. Eclipse1701d

    Eclipse1701d Prius Enthusiast

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    It could also be a weak 12 volt battery. I remember on my '07 the sound would last for a little while. After I changed the 12 Volt, the duration was shorter and the frequency was higher. I remember taking note of this so I would know, in the future, that when that pumping lasted a long time, it would be time to change the 12 Volt battery...
     
    #5 Eclipse1701d, May 2, 2014
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. The coolant heat recovery pump will usually run for several seconds upon startup and shutdown. The purpose of this pump is to circulate hot coolant from the coolant heat recovery canister to the engine, to speed up engine warmup and reduce exhaust emissions.

    2. The brake actuator pump will run for several seconds when the car is IG-OFF and the driver's door is opened. The purpose of that is to get the brake system ready for the car being driven. Once the car is READY, you can force the pump to run by repeatedly depressing the brake pedal. That is a way for you to familiarize yourself with the sound created by that pump.

    3. The problem would be if you find these pumps are running for an abnormally long period of time. That would imply unrepaired accident damage to the associated systems. There is an obvious safety issue if the brake system is involved, not to mention stress on the 12V battery which could lead to a no-start incident.

    4. A good idea to check the condition of the 12V battery and replace it if marginal.
     
    #6 Patrick Wong, May 2, 2014
  7. N7OKN

    N7OKN Junior Member

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    Very good. Thank you.
    I've tested the 12 volt battery (yellow top) and it reads 12.65 volts after the car has sat for a few hours. I then turned on the headlights for 10 minutes and tested it under load, 12.2 volts. I think it's OK. My question is, I've read conflicting reports about where the pump is on my '07.. Is it on the right side under the washer tank or under the inverter?
     
    #7 N7OKN, May 2, 2014
  8. Eclipse1701d

    Eclipse1701d Prius Enthusiast

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    The coolant thermos/pump is located behind the driver's side headlight.
     
    #8 Eclipse1701d, May 2, 2014
  9. N7OKN

    N7OKN Junior Member

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    Oops, sorry, I meant where is the brake actuator pump, not the coolant pump.
     
    #9 N7OKN, May 2, 2014
  10. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The brake actuator pump is located on the firewall. You need to remove the cowl tray that the windshield wiper motor sits in, for access to that pump.
     
    #10 Patrick Wong, May 2, 2014
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