1. Attachments are working again! Check out this thread for more details and to report any other bugs.

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

    Joined:
    Jun 5, 2023
    20
    9
    0
    Location:
    USA
    Vehicle:
    2013 Prius v wagon
    Model:
    Five
    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

    Joined:
    Mar 30, 2008
    24,546
    15,964
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    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

    Joined:
    Nov 29, 2020
    9,802
    1,711
    0
    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    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

    Joined:
    Jun 5, 2023
    20
    9
    0
    Location:
    USA
    Vehicle:
    2013 Prius v wagon
    Model:
    Five
    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

    Joined:
    Feb 21, 2017
    126
    60
    0
    Location:
    Orlando Florida
    Vehicle:
    2013 Prius
    Model:
    Two
    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

    Joined:
    Aug 14, 2022
    221
    61
    0
    Location:
    USA
    Vehicle:
    2013 Prius
    Model:
    N/A
    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
(You must log in or sign up to post here.)