This part was sitting on my motor mount, what is it?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Durian Grey, Sep 11, 2020.

  1. Durian Grey

    Durian Grey New Member

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    Car is a 2008 touring with 180k.

    As of yesterday I started hearing this deep, hollow rattle that's not really a rattle. It sounds like someone with a deep voice trying to repeat "gullum" as fast as they can. Doesn't really happen under acceleration but happens all the other times.

    I put the car on ramps and didn't find anything obviously out of order, the lower mount with the control bracket was old but not more jiggly than I would expect a mount with 180k to be. Then I found this part sitting on top of the control arm that the motor mount is on. One side of it seems like it was rubberized. Removing it didn't solve the gullum noise. Any ideas what it is?
     

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  2. valde3

    valde3 Senior Member

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    Tuned mass damper. It was attached to hole in engine mount bracket that the engine torque mount is attached to. Second tuned mass damper is still there. That's the rubber block.

    It's designed to reduce driveling vibration in a certain situation. In this case I wouldn't worry about it missing. When car gets old the rubber in mounts changes so damper is not probably correctly tuned anyways. And small vibrations are probably not going to cause problems.

    So there has to be something else wrong. If it's making the noise at "idle" can't you just listen to where it comes when it's on the ramps like this?
     
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  3. T1 Terry

    T1 Terry Active Member

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    Try putting the engine under load by anchoring the car to a pole, bonnet up and someone listening under the bonnet. My guess it is the exhaust pipe bouncing on the exhaust manifold as the built up pressure causes the springs that mount it in place to compress enough to let the pressure drop. Base cause is a blocked catalytic converter or blocked muffler. My taxi Prius suffered this problem and I believed the taxi companies mechanic that he had traced it to a worn timing chain. Problem was still there after I spent days replacing the timing chain.
    My taxi Prius has big miles on it, so unless your Prius burns a lot of oil and that has blocked the cat, I'd look at the muffler first.

    T1 Terry
     
  4. Durian Grey

    Durian Grey New Member

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    Thanks, that solves that! Sorry if I wasn't clear - the noise isn't there at idle. It's there at every speed and seems more due to road vibrations than bumps, if I go out of my way to hit potholes it doesn't seem any more severe.

    Anchoring the car to a pole is going to be logistically difficult but I'll give it a shot. If that's the cause, wouldn't I hear more noise under acceleration rather than less?

    I think I may have had a new exhaust installed in February of this year but need to check my records. Bad memory :confused:
     
    #4 Durian Grey, Sep 12, 2020
    Last edited by a moderator: Sep 14, 2020
  5. Durian Grey

    Durian Grey New Member

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    Ok, so no noise with the car stationary but revved. And the exhaust is new, so I doubt it's that. It sounds like the noise is coming more from the front left. Is there anything in the front suspension that I could check?
     
  6. valde3

    valde3 Senior Member

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    This doesn't sound like blocked exhaust at all. If you can hear the sound when engine is not running then it clearly can't be.

    As you hear it just as much on small than on big bumps maybe anti roll bar endlinks? Ball joints? Upper strut mount? Tie rods? Especially if the sound is metallic. If the sound is deeper then maybe anti roll bar mounts or suspension bushings. Test the parts and not just randomly replace parts.
     
  7. Durian Grey

    Durian Grey New Member

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    Can I check these just by jacking it up and seeing if I can wiggle them?
     
  8. Durian Grey

    Durian Grey New Member

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    Nevermind, I found a how-to on youtube. Four all four wheels, when the wheel is off the ground, there is no wiggle side/side, up/down, or when I try to wiggle it on the turning axis or any other way. I think this rules out the struts, ball joints, roll bar, etc? If nobody has any other ideas then it's off to the dealer I go :(
     
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