Brief rattle/knock at cold start

Discussion in 'Gen 4 Prius Main Forum' started by Teewin, Mar 11, 2017.

  1. Teewin

    Teewin Junior Member

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    Just picked up a 2017 Prius 4 for the wife a few months ago. I did a quick search to look for knocking rattle issues on a cold start but didn't find anything pertaining to gen 4s only 2010 and 2011 models saw this behavior. When left sitting overnight in our garage temps around 30 to 40. When I first start her car, as soon as the engine kicks on I hear a 1 to 2 second rattle noise which dissipates and doesn't happen again, even if I shut the car off and restart it. Anyone experiencing this? Oil level is half on the dipstick btw
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    How many miles on it, new purchase? I would think oil would have been at full mark when delivered to you; was it higher before?
     
  3. Teewin

    Teewin Junior Member

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    Yes new purchase, oil is the same, 2200 miles on it. Seems unlikely to cause a rattle even if the oil was at the bottom mark on the dipstick...
     
    #3 Teewin, Mar 11, 2017
    Last edited: Mar 11, 2017
  4. pakitt

    pakitt Senior Member

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    No rattle here, at 10000mi // 17000 since June 2016
     
  5. priusgto

    priusgto Active Member

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    Mine had the same rattle at cold startup with genuine Toyota oil but not with Mobil 1. Mobil kept it quiet for about 6500 miles, then the rattle started again. I changed the oil at 7k, again with Mobil 1, and all is quiet again.
    See this thread,
    Only Mobil 1 For My Prius | PriusChat
     
  6. Chippingawayatlife

    Chippingawayatlife Active Member

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    Can you upload a video so I can listen to see if I great something similar?
     
  7. alanclarkeau

    alanclarkeau Senior Member

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    I can often hear mine start first time in the morning, I wouldn't call it a rattle though - just slightly more noise than if it's hot. Much less noise than say a "normal" starter motor. Or my previous diesels starting.
     
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  8. bisco

    bisco cookie crumbler

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    congrats and welcome!
    just sounds like a normal toyota engine anomaly. 'snafu'. enjoy the mpg's!
     
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  9. Teewin

    Teewin Junior Member

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    Yeah it hasn't reproduced the noise. But I will post it once I am able to get it. Seems the Prius won't reproduce the noise when I have the camera on and ready to record...funky how that works. No wonder Toyota service can NEVER reproduce any customer issues... Haha
     
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  10. Chippingawayatlife

    Chippingawayatlife Active Member

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    I see. Yea I've always wondered about the pronounced noise and vibrations the engine makes during the first two cold turns. But like Alanclarkeau mentions, it's probably the lack of starter sounds that drowns out everything I'm not used to. I'm thinking as long as it pumps in oil before combustion, I'm at ease.
     
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  11. Oregon123

    Oregon123 New Member

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    2019 with 5k same issue. Did you ever figure out the reason?

     
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  12. alanclarkeau

    alanclarkeau Senior Member

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    That's noisier than mine - though to be honest, I've never listened from outside. Maybe check with your dealer.
     
  13. kithmo

    kithmo Couch Potato

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    Does it have 0w20 oil in it, thicker at cold oil such as 5w20 will not circulate as quick.
     
  14. dy/dx

    dy/dx Junior Member

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    My 2017 Prius has a rattle noise at start-up coming from the timing chain cover. Does anyone have an idea what is causing this noise? Is there a tensioner I can replace from the outside?
     
  15. -Yousef-

    -Yousef- Junior Member

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    I occasionally have the same rattle on start-up on my 2017 as well and it's been like that since new , now at 35km and I'd think it's a normal characteristic of this engine.
     
  16. dy/dx

    dy/dx Junior Member

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    Thank you Yousef for your response. It sounds like a metal to metal clatter with no oil lubrication for a second and then goes away. It only happens when the engine sits for a while. Do you have the same experience?
     
  17. -Yousef-

    -Yousef- Junior Member

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    Yes usually when the engine is cold as I notice it more during the winter months.
     
  18. RidiculousMPG

    RidiculousMPG New Member

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    Did anyone ever get a definite answer/solution on this? I have 2021 awd, 3,000 miles, so it still has oil from factory. When gas engine first starts, occasionally i hear this brief rattle/clicking noise from engine compartment for about 1-2 seconds (if you were not paying attention or had radio up you probably wouldn’t notice it). A little disconcerting……
     
  19. alanclarkeau

    alanclarkeau Senior Member

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    Just think - if you had, say a Corolla NON-HYBRID, and turned the key - you'd hear the whine of the starter motor and the ICE starting up - and wouldn't notice that momentary rattle/clicking for the racket from the starter.

    I occasionally hear it, but it doesn't worry me.
     
  20. alanclarkeau

    alanclarkeau Senior Member

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    Just think - if you had, say a Corolla NON-HYBRID, and turned the key - you'd hear the whine of the starter motor and the ICE starting up - and wouldn't notice that momentary rattle/clicking for the racket from the starter.

    I occasionally hear it, but it doesn't worry me.
     
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