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

Clunky sound when engine starts and more.

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by JRC1981, Feb 20, 2023.

  1. JRC1981

    JRC1981 New Member

    Joined:
    Feb 20, 2023
    11
    1
    0
    Location:
    77433
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Hi PriusChat,

    On start-up this morning there was a severe clunky sound when the engine first turned on. It smoothed out after a few seconds.

    My vehicle is a 2012 Prius plugin with 200k+ miles.

    I have a YT video of it that you can find by adding this string to domain - /shorts/ZrvsPPlkgyQ

    The sound was much more severe the first time.

    On a potentially related note, I had a brake booster and brake accumulator fail in late November. At that exact same time, my acceleration and mileage decreased noticeably. Acceleration seems sluggish - as if the electric motor isn't working as it should. The mileage went from a solid 50 to 35 or so. During the diagnostic and repair of the brake system, nothing came up as an issue. I changed out the 12v shortly after the repair, but the issue persisted.

    Apart from the brake system and a water pump, the car has been fairly good to us. Everything else is original except for the brake pad, 12v battery, and tires.

    Any thoughts on the issue?
     
    #1 JRC1981, Feb 20, 2023
    Last edited by a moderator: Feb 20, 2023
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,571
    48,862
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Start by making sure you’re up to date on all recommended Toyota maintenance.
    Then clean the egr circuit.
    Next, move on to things like throttle body cleaning, coils and injectors
     
  3. JRC1981

    JRC1981 New Member

    Joined:
    Feb 20, 2023
    11
    1
    0
    Location:
    77433
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Thanks, Bisco,

    Where do the sparkplugs fall on this list? (they've never been changed and need to be anyway)

    Seems like lower-hanging fruit and I can check the head gasket/coolant at the same time.
     
  4. nicoj36

    nicoj36 Active Member

    Joined:
    Oct 15, 2013
    494
    156
    0
    Vehicle:
    2010 Prius
    Model:
    II


    That's the usual Prius headgasket/rattle issue. The fixes for it are not the same. Some folks fix it by cleaning the egr, intake manifold. Some folks fix it by replacing coils and sparkplug. Some folks fix it by installing catch-cans, replacing pcv valve, etc.

    My advice, just give your Prius a full-blown TLC by doing all of the above. Replace all fluids as well like coolants and atf. Also, give it a bottle of fuel treatment and do this reset on this video.
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,474
    38,106
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    How's the coolant level?

    With the miles, and no mention of EGR cleaning, I'd test the head gasket integrity. A couple of things you can do (or have a mechanic do):

    1. Leak Down Test, where cylinders are pressurized one at a time, at TDC of compression stroke, using a special gauge set. You're looking for abnormally fast pressure drop (with the gauges), and looking/listening for evidence of air escaping, and where it's escaping.

    2. Boroscope inspection of the combustion chambers while the engine cooling system is pressurized, to look for coolant leaking into cylinders.

    Think this is a direct link to your video:

    2012 Prius Start-up - YouTube

    ^ hard to tell anything, audio very low
     
    PriusG909 likes this.
  6. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,475
    4,373
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    https://m.youtube.com/shorts/ZrvsPPlkgyQ

    That particular rattle isn't that bad, however, if it was more severe before, perhaps 5 to 20 seconds with an almost metal to metal rattle and the engine shaking, that's a head gasket for sure.

    If it is a head gasket, it will return. In the early stages it can take days or weeks between severe rattles.

    All the maintenance listed above is good to do on a good engine. I would verify that your engine is good before you do it. With high miles, a replacement engine or better yet. a rebuilt engine is often the end result. Rings are usually bad as well making a professionally rebuilt engine the smart choice. No use putting in $1000 or more dollars on maintenance until you know for sure what you've got.
     
  7. JRC1981

    JRC1981 New Member

    Joined:
    Feb 20, 2023
    11
    1
    0
    Location:
    77433
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Thanks everyone!

    The head gasket is failing. Confirmed by the dealership.

    $11,000 to install a used motor with 60k-70k miles.

    $3,500 for a new gasket.
     
  8. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,475
    4,373
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    You can do far better than that in the Houston area. Start with Houston Hybrids and ask for recommendations.

    Many can get a used engine installed for $3500 or less. Not the greatest solution unless you are ready to flip it.

    Smart shopping and a good independent shop will get you a rebuilt engine with new pistons and rings installed for less than $5k. This is the smart move if you want to keep it. Think about those $900 car payments for four years and rebuilt sounds good.

    A head gasket job is possible for $2k all in. Make sure you get a one year or better warranty as this is sketchy sometimes on a gen3.

    There is nothing special about the engine. People have swapped them in less than a day. Hybridpit in Cali will ship you a rebuilt engine. Do your homework.
     
  9. JRC1981

    JRC1981 New Member

    Joined:
    Feb 20, 2023
    11
    1
    0
    Location:
    77433
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Thanks RJ Parker,

    I laughed the service tech when he told me the price - not in a mean way, just at the absurdity of the situation.

    I did a search for Houston Hybrids but didn’t find much of anything besides a Hometown Hybrids out of Magnolia. What should I be looking for?
     
  10. JRC1981

    JRC1981 New Member

    Joined:
    Feb 20, 2023
    11
    1
    0
    Location:
    77433
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    I see what you are saying. Never mind.
     
  11. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    7,475
    4,373
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
  12. Daniel38

    Daniel38 Junior Member

    Joined:
    Dec 30, 2021
    1
    0
    0
    Location:
    Russia
    Vehicle:
    2012 Prius Plug-in
    Model:
    N/A
    This happens to many owners, at the freezing temperature of water, condensate freezes in the intake manifold, and the engine starts knocking at startup, I don’t think it’s worth worrying too much about this, Toyota has released a bunch of versions of the intake manifold, but the problem has not been solved.
     
  13. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,073
    14,978
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    It also can be the head gasket, which is why members will advise to check that. The dealership seems to have confirmed that in this case.

    My old Gen 1 started making startup rattles like that at around 198,000 miles and I never figured out why. I doubt it was the head gasket because I drove without further for four more years until an incident involving an eastbound Dodge Dakota, and it still was driveable after that, and I sold it to someone who drove it to Colorado. It also wasn't the EGR system because Gen 1 didn't have that. Seems it can be a number of things.