Testing compression on a new (used) Prius engine

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by ProblemPrius, Jun 15, 2023.

  1. ProblemPrius

    ProblemPrius New Member

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    Just purchase a used Gen 3 Prius engine off of eBay. Before I stick it in the car can I turn the crankshaft with an impact wrench on the pully bolt to get an accurate compression reading on each cylinder? If so, I presume I turn the crankshaft CLOCKWISE?
     
    #1 ProblemPrius, Jun 15, 2023
  2. ChapmanF

    ChapmanF Senior Member

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    A leakdown test may be more practical on an engine the car can't crank.
     
    #2 ChapmanF, Jun 15, 2023
    Mendel Leisk and Tombukt2 like this.
  3. Tombukt2

    Tombukt2 Senior Member

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    You'll need a lot more than an impact wrench you'll need some kind of electric motor that you can connect to the front pulley that can pull the engine around and at least I want to say $150 RPM or something like that I don't believe an impact would be up to the task not even a 1-in drive setup for truck use but yeah give it a shot.
     
    #3 Tombukt2, Jun 16, 2023
  4. ProblemPrius

    ProblemPrius New Member

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    Oh well, thought I'd ask. Unfortunately I don't have a leak down tester and running out of time now. From what I have been able to tell the engine looks nice. I pulled the plugs and they are all OEM Denso with similar looking normal wear patterns. I'm going to swap the plugs out with new Densos and put the engine in and hope for the best.
     
    #4 ProblemPrius, Jun 16, 2023
  5. Brucetafer

    Brucetafer Member

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    for god sakes don't put that impact near that engine... without a starter and flywheel typical setup, you're going to have a HELL of a time trying to Bench test it.. install it and let her eat!
     
    #5 Brucetafer, Jun 16, 2023
  6. Priipriii

    Priipriii Member

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    I did a leakdown test first, but i prefer compression test more. Because the compression gave me a more accurate reading when the leakdown helped pinpoint what i thought was wrong based on the noise, but i wasnt too sure if i had the piston dead top center or not, so i was second guessing myself the entire time. Compression test confirmed for sure what i already suspected. Way more accurate.

    Unfortunently, youd probably need your MG motor to spin it or something fast and strong enough, but also consistent. Youd be better off with a leaktest. Its like 20 dollars on amazon
     
    #6 Priipriii, Jun 18, 2023
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