Squeaking noise from engine on stage 1a

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Abarnabe, Jul 13, 2025.

  1. Abarnabe

    Abarnabe Member

    Joined:
    Jan 7, 2018
    163
    97
    0
    Location:
    Netherlands
    Vehicle:
    2010 Prius
    Model:
    III
    I've recently noticed a squeaking noise coming from the driver / transmission side of the engine bay on stage 1a, after transitioning to 1b I can't hear it anymore.

    I can't reproduce the sound in inspection mode.

    I thought it could be the engine coolant pump, but I turned it on with engine off with techstream, and there is no squeaking, so I would rule it out.

    The car has 310k KM.
    Transmission oil changed every 90k Km
    Virtually no engine oil consumption.
    No DTC codes.

    What could it be?
     
    #1 Abarnabe, Jul 13, 2025
    Last edited: Jul 13, 2025
  2. Brian1954

    Brian1954 Senior Member

    Joined:
    Jan 31, 2021
    1,898
    749
    0
    Location:
    South Central PA, USA
    Vehicle:
    2011 Prius
    Model:
    III
    Does the squeaking sound occur when the car is stationary or when the car is being driven on the road?
     
    #2 Brian1954, Jul 13, 2025
    Last edited: Jul 13, 2025
  3. Abarnabe

    Abarnabe Member

    Joined:
    Jan 7, 2018
    163
    97
    0
    Location:
    Netherlands
    Vehicle:
    2010 Prius
    Model:
    III
    it occurs when the car is stationary
     
  4. Abarnabe

    Abarnabe Member

    Joined:
    Jan 7, 2018
    163
    97
    0
    Location:
    Netherlands
    Vehicle:
    2010 Prius
    Model:
    III
  5. Abarnabe

    Abarnabe Member

    Joined:
    Jan 7, 2018
    163
    97
    0
    Location:
    Netherlands
    Vehicle:
    2010 Prius
    Model:
    III
    If I understand well in S1a MG1 and MG2 are not turning, the only thing spinning is the ice and torque limiter ( the clutch on the flywheel ).
    My theory is that the coil springs on the clutch developed some play and squeak, since they have no lubrication and they absorb the infamous startup shudders caused by shut off while the ice is still charging the hv battery.

    I can confirm the squeaking stops as soon as the ice is under load i.e. charging the hv battery
     
    #5 Abarnabe, Jul 14, 2025
    Last edited: Jul 14, 2025
  6. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    7,330
    3,833
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    I don't hear a squeak. I hear rattling.
    Check all connections/brackets, perhaps a clip holding a line broke.
    Maybe a motor mount is broken, or the heat shield rusted out?

    The shocks/struts don't squeak when the car is not moving.....
     
    Abarnabe likes this.
  7. Abarnabe

    Abarnabe Member

    Joined:
    Jan 7, 2018
    163
    97
    0
    Location:
    Netherlands
    Vehicle:
    2010 Prius
    Model:
    III
    i
    I also thought about the heat shields, I mended them a week ago, but the sound persits, it' s really high pitched, like the sound of worn drill trying to perforate some hard metal, but quite hard to hear, and I think it comes from the flywheel location.

    When MG1 engages at S1b the noise stops, it' s like it absorbs the vibration.,

    I was tempted to spray some wd40 on the flywheel springs if they can be reached from the plastic cover , but what if the cutch starts slipping?

    Here are some pictures of the mended heat shields.
     

    Attached Files:

    #7 Abarnabe, Jul 14, 2025
    Last edited: Jul 14, 2025
  8. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    7,330
    3,833
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    Do not spray any lubricant on the clutch surface!
    You can remove the lower cover and see if you see any metal parts at the bottom..

    You can also take a long screwdriver or metal rod and touch it to your ear and touch around the
    area you hear the sound. Using it like a stethoscope.
     
    Abarnabe likes this.
  9. CR94

    CR94 Senior Member

    Joined:
    Dec 2, 2014
    2,674
    1,158
    0
    Location:
    Northwestern S.C.
    Vehicle:
    2011 Prius
    Model:
    Two
    That's not possible.
     
  10. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    26,827
    17,593
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    The engine, MG1, and MG2 are linked by a planetary gear set that makes it impossible for only one to be turning, ever. They can either all be stationary, or at least two are turning.

    Because MG2 can't turn without the car moving, if the engine is turning and the car is stopped, the other thing turning is MG1.
     
    Abarnabe likes this.
  11. Abarnabe

    Abarnabe Member

    Joined:
    Jan 7, 2018
    163
    97
    0
    Location:
    Netherlands
    Vehicle:
    2010 Prius
    Model:
    III
    I had no chance yet to open the flywheel cover due to long holiday trip back to my home town in Italy, with up to 2200 meters mountain pass and MG teperature up to 132°c. The car was fully loaded with 2 adults 2 grown kids, full trunk a 50 kg bag on the roof and a bike.

    I could compare the sound I hear like a shaft rotating in a bushing without oil, for the first minute afyer engine start, than again it stops at stage 1b.
     

    Attached Files:

    #11 Abarnabe, Aug 20, 2025 at 4:39 AM
    Last edited: Aug 20, 2025 at 4:55 AM
  12. Abarnabe

    Abarnabe Member

    Joined:
    Jan 7, 2018
    163
    97
    0
    Location:
    Netherlands
    Vehicle:
    2010 Prius
    Model:
    III
    I opened the flywheel panels, the noise comes from there, at 10 seconds of the first recording the noise stops during the transition from s1a to s1b, when load is applied to mg1.
    it seems the springs developed some play, this can be heard in the second recording by moving the flywheel with a screwdriver.
    No parts found at the bottom, but if any I think they would be at the opposite side of the flywheel. Question is how long do I have before failure.
    video 1
    https://photos.app.goo.gl/kWuNCfjBfynMjruo8

    video 2
    https://photos.app.goo.gl/pJ2g7u2bHJ1etgfx7
     
  13. ASRDogman

    ASRDogman Senior Member

    Joined:
    May 29, 2018
    7,330
    3,833
    0
    Location:
    Florida
    Vehicle:
    2010 Prius
    Model:
    Two
    I think you should get a new clutch, or whatever it's called, can't remember off the top of my head.
    NO ONE can tell you when it's going to fail. I would suggest replacing it as soon as possible.
    Bad things could happen if it brakes apart, and you might be replacing the engine and transmission...