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Seafoam Piston Soak

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Tomy Giang, May 9, 2019.

  1. Tomy Giang

    Tomy Giang New Member

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    Has anyone tried a piston soak with any of the available cleaning products? Seafoam piston soaks have shown great improvements with older engines dealing with oil consumption issues. Given the issue with the small oil control rings (2010-2011), I would think a good piston soak should help free up some of the gumming that may have occurred.

    I might try this since I’ll be replacing my spark plugs. I need some measure of success other than anecdotal or reduced oil burning. I’m thinking of performing a compression check, but I’m unaware of the procedure for this car.
     
    #1 Tomy Giang, May 9, 2019
    Mendel Leisk likes this.
  2. cnc97

    cnc97 Senior Member

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    As far as the compression check, when you have the wiper cowl and such off, with the coils and plugs pulled, and injectors unplugged, put the car in ready and hit the gas, or turn the heat up full blast and put the car in ready. Either action will cause MG1 to spin the engine.
     
    #2 cnc97, May 9, 2019
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    There are a few threads here on the subject. Maybe just google "Priuschat" plus varous search strings, better than the Priuschat built-in search.

    Go straight to a leak-down test, which doesn't require the engine to be running? Or would doing the compression test first still be worthwhile?

    Advance Auto Parts - Down for Maintenance

    The above just stipulates that the cylinder being tested should have the piston at Top Dead Centre. OTOH, Eric the Car Guy (google his video) says it should TDC and on the compression stroke. The inference is that there might be a valve open on the exhaust stroke?

    Apparently too (from watching ETCG video), in a pinch you can just take the valve out of a compression tester, and use it to at least pressurize cylinder, listen for hissing air, watch for coolant bubbles.
     
    #3 Mendel Leisk, May 9, 2019
    Last edited: May 9, 2019
  4. Tomy Giang

    Tomy Giang New Member

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    Thanks @cnc97 ! That would crank the engine as you gas it, but would that give you WOT? I would think the electronic peddle corresponds with the throttle position, but wonder if there is a fail safe.
     
    #4 Tomy Giang, May 9, 2019
  5. cnc97

    cnc97 Senior Member

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    On the Prius, it simply commands MG1(starter/alternator) to spin the engine to 1200 rpm for starting. It will do this for 5-8 seconds, and in the absence of a response from the ignition and injectors, stop spinning. It will set a code, but it can be erased when you are done.
     
    #5 cnc97, May 9, 2019
  6. Peter123

    Peter123 Active Member

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    There is a compression test routine in tech info, if you have access to that. Seafoam may help, but when you start up the engine afterwards, you are going to gas everyone on your entire street. It does not smell nice.
    You may want to look at the chemical clean out described in this thread Oil burning rate of increase | PriusChat
     
    #6 Peter123, May 14, 2019
  7. PriusII&C

    PriusII&C Active Member

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    Have you tried the piston soak method? If you did, any update would be greatly appreciated.
     
    #7 PriusII&C, Jan 22, 2021
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