Cold Start Slight Forward Lunge Feeling?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Dave1UK, Apr 7, 2025.

  1. Dave1UK

    Dave1UK Junior Member

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    Just noticed this morning cold start, about every 15 seconds or so until the engine turns off there is a slight shake/lunge? Feels as if the car is accelerating (lunge forward - both brakes are engaged, not pressing anything just letting the car idle and warm up) for a second or two then just runs normally. Is this behaviour normal as a new owner can't tell.
     
    #1 Dave1UK, Apr 7, 2025
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  2. Mendel Leisk

    Mendel Leisk Senior Member

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    IIRC over 200k miles, newly acquired? Keep an eye on the coolant level. Do you know the seller? Could have stop-leak product in coolant, and starting to wear off: 3rd gen are plagued by head gasket failure, coolant leaking into combustion chambers manifests with rough cold-starts.

    I’ve commented in your previous thread.
     
    #2 Mendel Leisk, Apr 7, 2025
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  3. Dave1UK

    Dave1UK Junior Member

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    Coolant levels are and have been fine for now (thankfully). Coolant looks fresh, caps also clean.

    Just trying to figure out what normal cold start up etc should feel/sounds like. Will take a video tomorrow and upload it as easier to "diagnose/see" than trying to describe it, it's definitely not a rattle/knock like those currently on YouTube.

    Seller is a local garage. Not sure of the history of the vehicle unfortunately. I honestly don't think a stop-leak would of been used, it's not that common in the UK and garages wouldn't/generally don't recommended using it.

    Trying to get to a point to decide whether I spend some money on a secondary EGR/manifold set/spark plugs etc and do full service/clean up. Don't want to be doing so if head gasket is potentially going to be an issue as an added cost.

    Yes well aware appreciate all the help you've provided!
     
    #3 Dave1UK, Apr 7, 2025
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  4. bisco

    bisco cookie crumbler

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    i think it's normal
     
    #4 bisco, Apr 7, 2025
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  5. CR94

    CR94 Senior Member

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    Good question! You're the first to ask, as far as I know, and I've been reading Priuschat for over 10 years. My car occasionally does something like you're describing, usually while parked on a steeper uphill than usual. It must not be terribly harmful.
     
    #5 CR94, Apr 10, 2025
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  6. Dave1UK

    Dave1UK Junior Member

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    Oddly enough I haven't experienced it the past few days. I'm wondering whether it was possibly due to the way I engaged the parking brake etc.
     
    #6 Dave1UK, Apr 10, 2025
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