Rotate ICE by hand - no tools, hypothetically

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by pasadena_commut, May 9, 2026 at 2:30 AM.

  1. pasadena_commut

    pasadena_commut Senior Member

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    Hypothetical question.

    When doing a piston soak people often rotate the engine a little every so many hours by using a ratchet on the big nut on the pulley which is used to belt drive the water pump. Which led me to wonder, if the plugs were out and one just grabbed the sides of the big pulley wheel and turned it by hand, would that be enough force to rotate the motor? Doing this the water pump would also turn, so maybe too much friction from that to spin the motor that easily unless the belt was also removed? The usual piston soaks would also strip the oil from the cylinder walls and rings, I don't have any gut feeling for what that does to the force needed to rotate the motor. Does it become substantially more difficult to rotate as the treatment progresses?

    Safe direction is clockwise looking at that pulley from the passenger side wheel well?
     
    #1 pasadena_commut, May 9, 2026 at 2:30 AM
  2. Tombukt2

    Tombukt2 Senior Member

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    When doing a piston soak when you put this chemical in that you're using you rotated crank from tdc to like 3 o'clock half mast piston crowns at 12 hours I move crank till two middle pistons come L. Most to top let sit another six or so the back around till outters at almost TDC. Six more . Then it's time to dump or suck Out the chemical . And get prepped to fire . Yep hand turning the crank or use 19 mm wrench. 200k these engines purdy loose.
     
    #2 Tombukt2, May 9, 2026 at 7:49 AM
  3. ChapmanF

    ChapmanF Senior Member

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    Yes, with the spark plugs out, no sweat turning the crank pulley by hand. Feels like a sewing machine.

    The water pump doesn't pump much water at the speed you'd be turning by hand, so doesn't add much work.
     
    #3 ChapmanF, May 9, 2026 at 8:57 AM
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