Help Engine shaking and abnormal noise are not EGR problems

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by wukong sun, May 3, 2025 at 11:25 PM.

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  1. wukong sun

    wukong sun New Member

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    I bought a used car and drove it for two months. Recently, when I got off the highway, the engine started to shake and creak at idle.
    The noise stopped when I stepped on the accelerator, and I drove home at 40 miles per hour.

    I thought it was a common EGR problem, but when I opened the EGR valve and EGR cooler, they were very clean. It was obvious that they had just been cleaned not long ago, but there were some oil stains on the small EGR pipe of the intake manifold.

    After cleaning the intake manifold, I thought the problem was solved, but it still shook.

    I found that the cold start was normal, and it would run normally during the warm-up phase, and then it would start to shake after a minute or two.

    When I went out for a test drive, it would also shake when I stepped on the accelerator. Note: when the problem first occurred, it would not shake if I stepped on the accelerator deeply.
    NOTE: When the problem first started, if I pressed the accelerator deeply, it would not shake.

    Also, when the idle shake occurred during driving, the engine would stop shaking when I stepped on the brake, and it would run stably just like a cold start.

    Also, after the warm-up is completed, it will return to normal and not shake for a few seconds before it is about to shut down the engine.

    This is really strange. Is the Prius brake still a vacuum assist system?

    Is the warm-up load to charge the high-voltage battery heavy? The engine will shake

    What is the logical relationship here?

    Request guidance

    It's like being Sherlock Holmes
     
    #1 wukong sun, May 3, 2025 at 11:25 PM
    Last edited: May 3, 2025 at 11:31 PM
  2. MAX2

    MAX2 Senior Member

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    In order to logically answer all your questions, I will ask one - have you carried out any diagnostics of your problems using equipment, scanners or Techstream?
     
    #2 MAX2, May 4, 2025 at 8:09 AM
  3. Tombukt2

    Tombukt2 Senior Member

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    Too bad you have to find out like this . But at 10 plus years in ..
     
    #3 Tombukt2, May 4, 2025 at 8:18 AM
  4. Brian1954

    Brian1954 Senior Member

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    How many miles on the car?
     
    #4 Brian1954, May 4, 2025 at 9:22 AM
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    What’s the miles on it?

    Possible scenario: seller noticed engine shakes, tried belated EGR cleaning, which didn’t help, figured out head gasket was failing, dumped in stop-leak and put car up for sale.

    I’d inspect coolant condition, and borescope inspect the combustion chambers, preferably in the morning after driving previous day. If you can manage to pressurize cooling system during inspection it’ll accelerate coolant leakage. You’re looking for exceptionally clean cylinder top (typically coolant commences leaking in cylinder one), and coolant tears commencing from head gasket seam.

    the shake/rattle is typically due to coolant in combustion chamber. The EGR system clogging causes engine to run hot, which causes head gasket to let go, start leaking coolant, which results in pistons and crankshaft struggling to get over Top Dead Centre and so on.
     
    #5 Mendel Leisk, May 4, 2025 at 9:28 AM
  6. rjparker

    rjparker Tu Humilde Sirviente

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    Welcome to gen3 head gasket fails. Odds are good you were scammed as Mendel outlined and a replacement rebuilt engine is the only guaranteed fix since the engine is also known for bad piston rings. Carefully watch the passenger side coolant reservoir.

    Car Care Nut HG Borescope at 660s

     
    #6 rjparker, May 4, 2025 at 9:57 AM
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