Can EGR go bad?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by JSomms, Aug 24, 2025 at 2:15 PM.

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  1. JSomms

    JSomms New Member

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    Hi everyone! I’m new here but owned my Gen 3 Prius for 10 years. I have 209k miles on it and the death rattle started and some white smoke out the tail pipe. I did a quick YouTube check and egr and cooler needs a good cleaning. I followed the steps from Merv and cleaned my egr pipe and cooler. Put everything back and the white smoke is gone but still have the death rattle when car is cold. Can the egr valve be bad? If anyone can help, thanks
    Jerry
     
    #1 JSomms, Aug 24, 2025 at 2:15 PM
  2. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Likely head gasket has failed, is leaking coolant into cylinders, and the “death rattle” is due to engine’s struggles to compress the coolant.

    that was the first EGR cleaning?
     
    #2 Mendel Leisk, Aug 25, 2025 at 8:31 AM
  3. Brian1954

    Brian1954 Senior Member

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    I agree that the likely problem is that the head gasket is starting to fail.

    In the early stage of the leaking head gasket in the Gen 3 engine, the "death rattle" is due to misfires caused by the leakage of coolant into the cylinders. The coolant cause the spark plug to create a weak or no spark from the plug until the coolant is forced out through the exhaust valve of the cylinder. Then, the spark plug will work properly, and the misfire will stop occurring, and the engine will run smoothly again.

    In the advanced stage of a leaking head gasket, you could get enough coolant into the cylinder for the engine to struggle to compress the coolant in the cylinder. Once that occurs, you will bend or break the cylinder rod. If that occurs, it is time for an engine replacement.
     
    #3 Brian1954, Aug 25, 2025 at 9:10 AM
    Last edited: Aug 25, 2025 at 9:18 AM
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