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Engine Rattling Heavily

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Su Mo, Mar 15, 2023.

  1. Su Mo

    Su Mo Junior Member

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    Hi there, My car recently started rattling heavily when the engine fires up and then calms down and runs normally.

    My mechanic diagnosed and below were the findings:
    1. Cylinder 2 & 4 were misfiring out of which cylinder 4 was misfiring a lot of number of times.
    2. Figured that the ignition coils were bad.
    3. Surprisingly, dip stick showed there’s waster in the engine oil.

    Fixes:
    1. Drained all the oil. Replaced oil and oil filter. Dip stick showed no water this time.
    2. Replaced all the four ignition coils.

    The car is still rattling whenever the is coming on. Can u suggest what next I can do. Sparks?
     
    #1 Su Mo, Mar 15, 2023
  2. xliderider

    xliderider Senior Member

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    3. Water in the oil.

    Diagnosis = headgasket failed allowing water from the cooling system into the engine combustion chambers, that's what is causing the rough, shaky engine and water in the oil.

    Your mechanic doesn't sound like a very competent one. You should seek out another.

    Posted via the PriusChat mobile app.
     
    #2 xliderider, Mar 15, 2023
    bisco likes this.
  3. bisco

    bisco cookie crumbler

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    how many miles on her? ever cleaned the egr circuit? does she burn any oil?
     
    #3 bisco, Mar 15, 2023
    Mendel Leisk likes this.
  4. JC91006

    JC91006 Senior Member

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    Fixes:
    1. Drained all the oil. Replaced oil and oil filter. Dip stick showed no water this time.
    2. Replaced all the four ignition coils.

    Number 1 sounds absurd. If you replace the oil and the oil filter, it would not show water. Water (coolant) gets in there when there's a bad headgasket, changing the oil doesn't fix a darn thing.

    Number 2, well you should replace the spark plugs too, after you fix the headgasket of course.
     
    #4 JC91006, Mar 15, 2023
  5. rjparker

    rjparker Tu Humilde Sirviente

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    Unfortunately back in January it may have been just a head gasket.

    Now the very common head gasket problem has progressed. Water in the oil is end stage. Have to assume there is very serious piston damage by now. A used or rebuilt engine or junking the car is in its future.

    The problem does not present in the same way conventional cars do with a failed head gasket. An all aluminum engine often warps the head. Confuses uninitiated mechanics and dismayed owners almost every time.

    Shudder video
     
    #5 rjparker, Mar 15, 2023
    Last edited: Mar 15, 2023
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