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Cooling System Noise (mp3 included)

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by afmcgraw, Feb 25, 2010.

  1. afmcgraw

    afmcgraw New Member

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    I originally posted this in the tech discussion forum, but it took a while for me to get a recording of the sound. I thought this might be a better forum for it.

    My '05 has developed a strange noise from the engine compartment. It sounds like a pump or valve cycling on and off, about once per second. It comes up seemingly randomly and might last for a few seconds or near 30 seconds, engine on or off. It has been happening for the last 30k miles or so. I'm fairly certain that it hasn't always made the noise, as it is pretty noticeable in the cab. I also noticed that my in-law's '04 has the same noise, but less frequently.

    It's definitely coming from the thermos bottle area. I can feel it when I touch the plastic tee on the bottom of the thermos bottle.

    I connected my Autoenginuity scan tool, and cycled the water pump and water control valve(s). The water pump makes a nice even whirring sound, and the noise comes up after cycling the water valve.

    No MIL for a failed coolant flow control valve. Any thoughts?

    From the cab, the clicking in the recording isn't really evident, but it is when you get up close to it.

    Does this noise sound familiar to anyone?
     

    Attached Files:

    #1 afmcgraw, Feb 25, 2010
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  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The noise is not familiar. However based on the above, it appears that you've isolated the noise to the coolant heat recovery system valve. If there's no DTC, then why worry?
     
    #2 Patrick Wong, Feb 25, 2010
  3. saechaka

    saechaka Member

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    Check out my last post on this post. I think I have the same noise and was told it might have something to do with the brakes. http://priuschat.com/forums/toyota-...eaky-chs-water-pump-new-tsb-7.html#post804756 I hope galaxee can chime in and verify if it will be an issue. I've had that noise since 164k and still have it now at 184k.
     
    #3 saechaka, Feb 26, 2010
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    If you can induce the noise by repeatedly depressing the brake pedal, then it is caused by the brake actuator assembly. However if you don't have any brake warning lights on and don't find that your braking is impaired, then I would not worry - unless you wish to spend $2K just to get rid of that noise.
     
    #4 Patrick Wong, Feb 26, 2010
  5. afmcgraw

    afmcgraw New Member

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    Since it didn't make the noise since it was new, I'm concerned that it's a sign of an impending failure. I'm not losing sleep over it, though.

    I know it's not the brake actuator. I'm familiar with the sound that it makes when you pump the pedal. No brake issues, no ABS codes, and I recently bled the system with a scan tool with no issues.

    Since I have heard two 100,000mi+ 2nd gens that make this same noise, I have to think that someone else has heard it.
     
    #5 afmcgraw, Feb 26, 2010
  6. afmcgraw

    afmcgraw New Member

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    Anybody else? Unless the radio is on, this noise is obvious, especially when the car is stopped at a traffic light.

    Does this mp3 sound familiar to anyone who had an eventual coolant control valve failure?
     
    #6 afmcgraw, Mar 18, 2010
  7. slipperytoast

    slipperytoast Junior Member

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    It's the water control valve (may not be the official name as I'm recalling from memory). I've had this noise for over 3 years on my '05 Prius and 2 dealers were not able to find the cause until today. The part costs ~$60 and it's easily overlooked because it's not the pumps indicated in the bulletin, if it wasn't for the diligent mechanic today it would still not have been found. But I actually declined the repair because I've been complaining about the noise and every time they claim to not hear it. Now that my warranty is expired they won't cover it. Since I couldn't prove the noise started before the warranty expired I decided to give my money to another shop that hopefully will give me better customer service.
     
    #7 slipperytoast, Mar 23, 2010
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  8. Bob64

    Bob64 Sapphire of the Blue Sky

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    call up toyota's customer service line and complain. There should be records that you brought it in and that they "couldn't duplicate" the issue. You should be able to get them to pay up.
     
    #8 Bob64, Mar 23, 2010
  9. afmcgraw

    afmcgraw New Member

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    Finally a fellow noise victim! I figured that it was the coolant control valve, but was surprised how strongly I could feel it on the thermos bottle. I guess the noise is carried through the coolant

    You're talking about the green part in this pic? http://www.techno-fandom.org/~hobbit/cars/training/800/cours-2-5-bottle.gif

    Thanks to Toyota's awesome customer service, we can no longer look at parts diagrams on sites like Toyodiy!

    I wonder what it takes to trigger a DTC for the valve. I assume that it's switching back and forth because of a bad position sensor, or being on the border between two settings.

    I hope it lasts, since I just did the coolant. I'm tempted to replace it just because it's annoying.
     
    #9 afmcgraw, Mar 23, 2010
  10. slipperytoast

    slipperytoast Junior Member

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    I don't know what DTC means but I'm assuming it means the computer diagnostic tool or something? Well the technician didn't find it with the computer, when they initially couldn't hear the noise today i said let's take a drive, so I got in with the tech and after about a mile he heard it, we pulled over the side of the road and looked under the hood but he couldn't locate it exactly, he even disconnected the top pump to eliminate it out of the equation, then said he'll drive it right to the lift and not shut off the car. About an hour later the manager informed me that it was the valve.

    Bob64, I will call Toyota but not sure if I want to go back there. Ever since I bought the car (BTW, it's Bay Ridge Toyota in Brooklyn, NY if you're wondering) and they sold me on the ripoff dealer maintenance plan, I feel the combination of stupidity and anger for being ripped off every time I go there.
     
    #10 slipperytoast, Mar 23, 2010
  11. saechaka

    saechaka Member

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    Wonderful news. Great work finding the cause. I was worried about this noise for awhile. I'll put it on my to do list when I hit 200,000 miles in 6 months. I will get 20% discount from a dealer for cars over 200,000 miles.
     
    #11 saechaka, Mar 23, 2010
  12. afmcgraw

    afmcgraw New Member

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    Sorry for the unexplained acronym use. DTC = diagnostic trouble code, MIL = maintenance indicator light.

    The valve triggers a DTC if the position sensor gets stuck (P1121). Maybe it doesn't have a threshold for a intermittent sensor value. The TSB is for the stuck sensor.

    http://ww2.justanswer.com/uploads/skyvisions/2008-05-30_223901_prius.pdf

    Just a thought: on my 1st gen Insight, the position sensor pot in the EGR valve gets dirty/worn out in the position where it spends the most time. This leads to inconsistent EGR position readout, and makes the car bounce in and out of lean burn at light throttle, leading to a bucking feeling. If the prius coolant control valve has a pot-based position sensor, maybe it has a similar issue, and the ecu is trying to correct for an odd value readout. The noise sure has a consistent frequency though...
     
    #12 afmcgraw, Mar 24, 2010
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