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Engine Rattling/Buzzing/Fluttering

Discussion in 'Gen 3 Prius Main Forum' started by Alexikor, Apr 27, 2024.

  1. Alexikor

    Alexikor New Member

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    Location:
    Arizona
    Vehicle:
    2010 Prius
    Model:
    II
    Hi all,

    I have a 2010 Prius with 197,000 miles. In the past year, I've heard the engine make a rattling/buzzing noise under acceleration. Nothing like the chunky EGR rattles, this is more like a dieseling/dried-beans-in-a-can noise. Watch the attached video with headphones. The noise is heard between the 0:09 and 0:13 marks.


    • The noise is easier to hear at speeds less than 25mph, but I've occasionally heard it at speeds above 70mph.
    • The noise is intermittent. Similar conditions of driving and weather do not consistently reproduce the noise.
      • However, the noise happens more often in the Arizona summer than winter.
      • The last couple of "fast" turns from a standstill (eg heavy acceleration while also turning sharply) have produced the noise - oil/fluid starvation?
    • Keeping the oil topped off, something I started about 6 weeks ago, helps reduce how often the noise is heard, but it still comes up.
    • So far, it's only a noise, no vibrations are felt in the cabin or steering wheel
    • My mechanic says that it's okay for a prius of this age to make the noise as "the cylinders shake and tremble as they move up and down inside the block" which doesn't give great comfort to me. He also said the spark plugs look clean. The spark plugs have 60,000 miles on them.
    • I have not checked the EGR circuit

    Any ideas what it could be?
    Follow-up question, anyone have mechanic recommendations in the Phoenix metro area?
     
    #1 Alexikor, Apr 27, 2024
  2. bbrages

    bbrages Junior Member

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    I didn't watch the video, but there are a lot of thin sheet metal heat shields on and around the catalytic converter. With age, they rust enough to come partially unattached, making rattles at certain loads and rpms. That would be my first thought for tin-can type rattles.
     
    #2 bbrages, Apr 29, 2024
  3. Alexikor

    Alexikor New Member

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    2010 Prius
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    II
    bbrages, thank you for the reply. I'll take a look underneath and see if anything is loosey-goosey when I do the oil change and coolant change. Sorry for the late reply, I kinda thought Priuschat would send an email update when someone replied to the thread.
     
    #3 Alexikor, Jun 8, 2024
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Vehicle:
    2010 Prius
    Model:
    Touring
    How long have you had it?

    If the EGR's never been cleaned it's more'n likely the head gasket.
     
    #4 Mendel Leisk, Jun 8, 2024
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    2010 Prius
    Model:
    Touring
    It can if you set this in preferences:

    upload_2024-6-8_12-42-2.png
    upload_2024-6-8_12-42-44.png
     
    #5 Mendel Leisk, Jun 8, 2024
  6. Alexikor

    Alexikor New Member

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    Location:
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    Vehicle:
    2010 Prius
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    II
    Mendel, I've had the Prius for 14 years. Thank you for showing me the preference page.

    Currently reading the through both the head gasket and EGR cleaning posts on this forum, and it looks a little daunting. What other clues would there be to pinpoint the issue? I will be underneath the Prius in a couple weeks to change the coolant and oil.

    Another stat which may be useful. Driving around Phoenix, AZ in 110°F air with the AC set to 77°F blowing at 3 bars, the Prius shows 40mpg. On the North American East Coast (Georgia) where temps are cooler, driving around town using the same AC settings, the Prius would show 50mpg.
     
    #6 Alexikor, Jun 8, 2024
  7. Mendel Leisk

    Mendel Leisk Senior Member

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    Head gaskets have usually been failing at the adjoining wall between cylinders one and two (as you stand at front of engine bay, cylinder one is at left end), on the exhaust (far) side.

    leak-down tests can been used to test head gasket integrity. Very popular though is to pressurize the cooling system (at the reservoir) and then do a boroscope inspection of the cylinders. This will require removal of the windshield wipers and metal cowl beneath, in order to remove spark plugs.

    you’re looking for:

    1. exceptionally clean piston tops
    2. Tears of coolant forming and running down from the head gasket seam.

    @NutzAboutBolts spark plug replacement video:

     
    #7 Mendel Leisk, Jun 9, 2024
  8. Alexikor

    Alexikor New Member

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    Vehicle:
    2010 Prius
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    Thank you for the tips and video. Ordered a borescope from McMasterCarr today. Will take a look next weekend. Not easy to work in the Arizona heat in the evening
     
    #8 Alexikor, Jun 9, 2024
    Mendel Leisk likes this.
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