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Grinding noise for 20-30s at cold startup...

Discussion in 'Generation 1 Prius Discussion' started by luckydjuju, Nov 12, 2012.

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  1. luckydjuju

    luckydjuju New Member

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    Dear forum readers,
    my G1 prius (2001) started making a grinding noise when I start it up in the morning. There are no warning lights (yet) and it drives fine, but that noise can't be good -- something will fail shortly. I've searched the internet quite thoroughly and there was one similar problem reported, which ended up being linked to the ABS pump. The noise seems to come from the inverter, or somewhere under the inverter. I took a video of it and posted it here. If anybody has a clue what may be happening, I would be very grateful for your help.
    Thank you!
    - Julien
  2. bwilson4web

    bwilson4web 03 and 10 Prius

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    Sorry, Quicktime does not understand ".MTS" file format.

    Bob Wilson
  3. ChapmanF

    ChapmanF Senior Member

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    I can't watch your video here, but a quick check to start zeroing in on what your sound could be....

    If you just turn the key to ON (not to the START position, no need for the car to be READY), then pump the brake pedal a bunch of times, you should be able to start the brake accumulator pump. It makes a kind of buzz/whirr for a dozen or two seconds, then stops with a toink. Sometimes it will do this a few times in a row (whirr-toink whirr-toink whirr-toink). You can listen to that any time you want (just by pumping the brakes until the pump kicks in) and see whether that is the sound you are hearing.

    If so, don't worry. That's just what it sounds like.

    -Chap
  4. joedirte

    joedirte Member

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    Wow..

    Well it isn't the brake noise, that sounds normal. Car starts and sounds normal.

    Then after about 10 seconds it starts making 1s pulses of what sounds like when you engage a starter into a moving flywheel... Or a tin can dragged along a rough concrete.

    It might be coming from the coolant pump.

    It does sound louder under the inverter.. Did you place your hand on inverter metal to feel for this noise? It could possibly be something like air pockets in the coolant getting sucked in by the pump circulation and vibrating the metal of the inverter case... Like the sound a pool pump might make sucking in air...

    But really I guess something in transaxle, but what would make intermittent noise like that... Other than air pockets... But that is loud..

    Possibly stick your head under the car and see if you can hear it coming from the valve on the catalytic converter on the exhaust.. possibly that might be making a scraping noise??? long shot I guess..

    If you start car and immediately start driving in reverse does it make the noise?

    When you start it like this, if you step on gas and increase RPM does it change the noise..

    If it is the transaxle and MG1 or the chain, then you should be able to step on brake with left foot, shift into D and step on the gas while holding in the brake, and see if that impacts the noise at all. That will engage the moving parts in transaxle under load..

    If you put car to ready does the ICE ever shut off?

    Upload that thing to a YouTube account, it can convert your video.
  5. luckydjuju

    luckydjuju New Member

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    Sorry about the file format. Here's the video uploaded to YouTube (I also edited the link in the first message)
    The noise also happens without turning the ignition on, as of this morning.
  6. joedirte

    joedirte Member

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    Wat u mean noise happens without turning on ignition.

    If the car doesn't say READY then there is no high voltage and rules out that being an arc'ing noise.

    What is running with key in ACC? some computers, the cabin fan, the capacitors for the brake system that have 12V on them. a 12V relay in the fuse box that is high speed clicking???

    If you want any help diagnosing it, you need to be more specific about when it happens, and feel around in there for mechanical vibration. If it does it with key in but not READY, then it should be easy to diagnose.
  7. luckydjuju

    luckydjuju New Member

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    I had taken the car to a trusted mechanic in the meantime, in the off chance that they would know what is going on straight away, which is why I haven't been able to perform the tests that you suggested. They did not manage to diagnose the problem (it is quite difficult as it is short lasting, and can only be reproduced a couple of times a day...) and want to take the car apart so as to be better able to hone in on the defective part when the noise arises again. This will be too costly and I'm getting the car back in the afternoon. I'll start the self diagnostic process then, and will likely need your input shortly... Thank you!
  8. joedirte

    joedirte Member

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    put hands on relay see if you can feel one chattering.

    ALl I can figure is that it is high voltage arcing inside inverter or one of the orange wires. Maybe some type of air bubble coolant noise, or pump making noise somehow. Maybe some exhaust noise or the cat exhaust diverter valve.. It sounds like it is the inverter aluminum vibrating.

    If you put car in reverse, step on brake and give it some gas for a few seconds, the ICE will shut off in that first 30 seconds so you can hear it better (?)
  9. priusenvious1

    priusenvious1 Member

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  10. scotman27

    scotman27 Active Member

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    that is really something. that just sounds electrical, or something rubbing metal. sounds loud over the inverter. are you getting any lights on the dash
  11. luckydjuju

    luckydjuju New Member

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    Sorry for the long lapse... the noise was gone for a while, but now came back, and lasts longer -- some mornings, for up to 1 minute. Which means I had a chance to feel around for vibration. I found the part that vibrates: reaching my hand behind the inverter (towards the dashboard), there is a small metal(?) part, with perhaps 5 or 6 metal hoses going into/out of it. I'll try to take a picture of it. I don't know what that part is but it vibrates when the noise happens: that is where the noise comes from -- or at least it is connected to the part that is the source of the noise.
    Let me know if you know what part I might be talking about...

    No lights nor warnings on the dash, to answer scotman27's question.

    Also (obviously?) it is not a relay in either of the fuse boxes.
  12. bwilson4web

    bwilson4web 03 and 10 Prius

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    Sounds like the brake pump and master cylinders. There is a strong motor that charges the accumulator. If you press the brake pedal, does the noise change?

    Bob Wilson
  13. luckydjuju

    luckydjuju New Member

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    Started the car up this morning, waited for noise -- then, during noise, applied brakes (pumping) and this stopped the noise momentarily.
    Here's a picture of the part that vibrates during the noise.

    Anybody understands why the noise (mostly) only happens upon a cold startup? (Sometimes it will come on briefly while driving). And what part should I look into replacing?

    Attached Files:

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  14. bwilson4web

    bwilson4web 03 and 10 Prius

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    That looks like the brake assembly to me. First, make sure there brake fluid level is OK. If not, top it off and hope for the best. But loss of brake fluid is not good either as one wonders 'where did it go?'

    If filling the brake fluid doesn't solve the problem, it is likely to sooner or later be expensive, $1,000. Although one might get a used part from a salvage yard, the real risk is that any metal filings might have contaminated the brake lines. If so, at a minimum, everything gets flushed and there is still a risk of contaminated caliper and rear brake actuators.

    Bob Wilson
  15. luckydjuju

    luckydjuju New Member

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    Brake fluid is at the proper level. Perhaps it would be worth flushing the brake lines first, and hoping it is due to an air bubble rattling the brake accumulator pump? (just putting words together here -- I have not properly studied the diagrams for the brake system...)
  16. Eg Egemarke

    Eg Egemarke New Member

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    Please recheck your brake fluid, my 2000 prius has the EXACT same sound, i checked the brakefluid and put a finger in the container, it is well between low and high. but there is only like 2 mm brakefluid in the container to the bottom. I have the same level as yours on the youtube video. i have refilled/topped up the brakefluid to max, and now it have a lot less rattle.
    But since mine has been rattling for almost a year i think i have to bleed the actuator. i will do this as soon as possible at work.
    Please read this article:

    Brake Job: Toyota Prius: Brake and Front End

    i am pretty convinced this is the problem, that the pump is getting air, the noise it makes fits this theory.
    HereĀ“s and arthicle on how to bleed the entire system:
    C1256 low pressure accumulator- ABS beep | PriusChat
    Sorry for the Bad english i live i Sweden and have been a Prius owner for 4 years and own a 2007 and a 2000

    Regards Eg Egemarke
  17. Katie Harker

    Katie Harker New Member

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    My 2003 prius is experiencing the same grinding noise that you posted. What did you find to be the problem? It just started for me a month ago. The Toyota garage and another mechanic have yet to diagnose it. Any help would be much appreciated.

    Thanks
    Katie
  18. luckydjuju

    luckydjuju New Member

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    Well, it's been a year since the first symptoms. The noise was gone for a long while, it just came back in the last couple of weeks. Except that now it goes on for several minutes. It has been clear that it is a problem in the brake system, since I feel vibrations in the brake pedal. Today, I finally got a warning signal, a very unpleasant one: BRAKE and ABS lights on, and a very loud high pitched tone. I guess it is time to have a thorough check of the brake system, but it does sound like air getting in the brake accumulator pump (as Eg suggested). Should I start by having the brake lines bled and refilled, hoping that the pump hasn't been too damaged by running with air in it so many times?
    - Julien
  19. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes. If that doesn't help then the brake actuator assembly probably will need to be replaced.
  20. b787

    b787 New Member

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    Any update on your situation? My 2002 model is making the exact same noise at startup, but there are no warning lights yet.
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