Noisy engine at idle

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Frontporch, Sep 6, 2019.

  1. Frontporch

    Frontporch Junior Member

    Joined:
    Dec 18, 2015
    57
    13
    0
    Location:
    Nj
    Vehicle:
    2007 Prius
    Model:
    N/A
    I have a 2007 Prius that I bought with 125K miles and it now has 190K. It has been a great car overall, but recently I am concerned about engine noise. I will come clean about my shortcomings on maintenance and any blunders in an effort to narrow down what might be happening.

    I replaced my tires, that had some uneven wear, and now the prius drives whisper quiet. Its a good time to start listening at all the other noises.

    The motor sounds louder than normal around the valve cover area. Not a typical valve tapping... maybe a chain? Its a rattle. Not exhaust noise. Doesn't get any worse during acceleration, most noticeable at idle when not many other noises. With the hood closed it can almost be ignored... but with the hood open, staring at the motor, it has me worried.

    About 6-8 months ago, I noticed my oil was low... really low. So low that when I drained it I put it back in the quart bottles to see how much was drained. 1.5 qts. There was no indication on the dash of any issues. Replaced the oil and has not been losing since.

    Recently I took a 600 mile trip and when I was about to return, I checked the oil. I couldn't get a good read on the dipstick and was convinced that I was low again, so I added a quart. Measured the next morning after I got home and I was overfilled. I immediately siphoned out oil to put me at the full level.

    Believe it or not I am otherwise pretty handy.

    Any thoughts as to what might be going on? I don't mind a little rattle and hum, and the prius drives perfectly. I am more worried about the car dying on the highway or worse a bridge or tunnel.
     
    Mendel Leisk likes this.
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    17,968
    5,936
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    If you keep checking the engine oil level you will be good. It is pretty normal to hear valve train noise, like a sewing machine. With 190K miles the engine clearances have worn a little even before you allowed the oil level to run low.
     
    Dxta likes this.
  3. Frontporch

    Frontporch Junior Member

    Joined:
    Dec 18, 2015
    57
    13
    0
    Location:
    Nj
    Vehicle:
    2007 Prius
    Model:
    N/A
    Hi Patrick. I think the noise is something more than valve train. I have had other "noisy" Toyotas that were primarily valve noises, this is different. This noise also doesn't go away after the engine is warmed.
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    17,968
    5,936
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    Maybe the timing chain is getting loose?
     
  5. Frontporch

    Frontporch Junior Member

    Joined:
    Dec 18, 2015
    57
    13
    0
    Location:
    Nj
    Vehicle:
    2007 Prius
    Model:
    N/A
    if it were a loose timing chain, the noise would probably be it banging against guides? Any thoughts on repair or living with what might be a loose chain?

    With the high mileage it has, and the overall worn appearance of the car, I would probably just live with some noise if I didn't have a high probability of getting stranded.

    I also had previous plans to replace this car, but I still would like to know whats going on in the event that I pass it on to someone else.
     
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    17,968
    5,936
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    It is not easy to remove the engine front cover while the engine is installed. I suggest living with ithe noise unless it bugs you so much that you have the energy and ability to remove the engine for that purpose.
     
  7. Skibob

    Skibob Senior Member

    Joined:
    Sep 14, 2018
    2,594
    1,312
    0
    Location:
    Northern California
    Vehicle:
    2006 Prius
    Model:
    N/A
    You could get a mechanics stethoscope and poke around listening for the noise.
     
    Raytheeagle likes this.
  8. Frontporch

    Frontporch Junior Member

    Joined:
    Dec 18, 2015
    57
    13
    0
    Location:
    Nj
    Vehicle:
    2007 Prius
    Model:
    N/A
    I tried to use a mechanics stethoscope but it didn't tell me much.. I put the end on the valve cover and by the water pump and it sounded the same to me, noisy but maybe not the same as the noise I hear without the scope. I really don't use these much, so might just be I suck at diagnosing noises. Maybe I will put it up on ramps and listen from underneath.
     
  9. Dxta

    Dxta Senior Member

    Joined:
    Nov 7, 2016
    1,710
    613
    0
    Location:
    Lagos
    Vehicle:
    2008 Prius
    Model:
    II
    It might be the VVTi camshaft gear already failing.
    If its the VVTi, due to wear and tear, replaced them.

    Y not open up the valve cover, turned the engine to TDC, and try to feel the slack on the chain. If it feels slack, then you need to replaced the timing chain.
     
  10. Frontporch

    Frontporch Junior Member

    Joined:
    Dec 18, 2015
    57
    13
    0
    Location:
    Nj
    Vehicle:
    2007 Prius
    Model:
    N/A
    I probably will not tear apart this motor. Really more concerned about a sudden failure and being stranded. My concern is when does a noise become a serious concern when you are not actively burning oil, notice any issues with drivability or increased noise on acceleration. I think Toyota tends to be bullet proof and I am already driving a "clunker". Just looking for help determining has a good chance of being a red flag with these cars.
     
  11. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    81,487
    35,212
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    can you post a recording?
     
  12. edthefox5

    edthefox5 Senior Member

    Joined:
    Jul 25, 2007
    7,321
    3,085
    0
    Location:
    Clearwater, Florida
    Vehicle:
    2007 Prius
    Model:
    Two
    My opinion is the motor may have incurred some damage running it so low on oil. Your first post infers that your not good on upkeep.

    The engine sounds exactly like a sewing machine no rattles at all. Rattle is bad. if it was me I would put the car in inspection mode let it warm up and start listening. Pull the oil fill cap off the valve cover while its running and see if you hear rattling.

    Gon on YouTube and search PRIUS INSPECTION it will show you the chicken dance to put the engine in continuous run mode for inspection. It will idle endlessly till shut off. With it running get under the front of the car near the engine and listne for knocking or other ominous noises.

    Its pretty easy to take the valave cover off. I have included pictures of the valve train and chain pictures for looseness checking.
     

    Attached Files:

  13. oldtechaa

    oldtechaa Member

    Joined:
    Dec 28, 2018
    148
    81
    0
    Location:
    KY
    Vehicle:
    2008 Prius
    Model:
    II
  14. Frontporch

    Frontporch Junior Member

    Joined:
    Dec 18, 2015
    57
    13
    0
    Location:
    Nj
    Vehicle:
    2007 Prius
    Model:
    N/A
    I can't say it sounds like the video from oldtechaa. The noise isn't very noticeable from inside. It definitely does not appear only when accelerating. I think it is noisy overall and doesn't sound like it gets worse under load.

    I will try and post the noise. Any suggestions on how to post that? Youtube link?

    I did see a post on youtube about a water pump noise. Sounds like that... and my pump is original.


    Thanks for the suggestion on maintenance mode. Wrote those steps on an index card and will put in owner's manual for future reference.

    I will try to do some more info gathering tonight. Really appreciate everyone sticking with me on this.

    By the way, if the valve cover is removed, can the gasket be reused?
     
    #14 Frontporch, Sep 10, 2019
    Last edited: Sep 10, 2019
  15. Patrick Wong

    Patrick Wong DIY Enthusiast

    Joined:
    Mar 8, 2008
    17,968
    5,936
    0
    Location:
    Green Valley, AZ
    Vehicle:
    2015 Prius
    Model:
    Two
    Do not reuse the valve cover gasket. You also need to apply some RTV sealant at the front of the engine where the front cover attaches to the cylinder head.
     
    Raytheeagle and Skibob like this.
  16. Frontporch

    Frontporch Junior Member

    Joined:
    Dec 18, 2015
    57
    13
    0
    Location:
    Nj
    Vehicle:
    2007 Prius
    Model:
    N/A
    Anyone know if it is OK to idle without the accessory drive belt on?

    I did this with my Ford Ranger to rule out noise issues. I want to remove the water pump to see if it is producing the racket, but I just don't know if there are any sensors that would have a panic attack.
     
  17. Mendel Leisk

    Mendel Leisk Obtuse Angler

    Joined:
    Oct 17, 2010
    34,595
    23,554
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    I like that. :)
     
  18. Skibob

    Skibob Senior Member

    Joined:
    Sep 14, 2018
    2,594
    1,312
    0
    Location:
    Northern California
    Vehicle:
    2006 Prius
    Model:
    N/A
    As long as you start with a cool engine and run it for a very short time you should be fine. And by short time I mean 15 seconds or less. That should be more than enough time to know it that’s the problem or not
     
  19. edthefox5

    edthefox5 Senior Member

    Joined:
    Jul 25, 2007
    7,321
    3,085
    0
    Location:
    Clearwater, Florida
    Vehicle:
    2007 Prius
    Model:
    Two
    yes i can clearly hear what your posting about its like a low toned rattly rumble. Not good.

    Hopefully its the idler pulley bearing as you suspect but I doubt it it sounds like heavy rumbling like lower end to me.

    Do what i suggested and get under the frontt of the car with engine running. may hear some very bad stuff downstairs.

    With cold engine you can run the engine for a while with the belt off. Too bad you dont have a Scan gauge then you can tell when you reach op temp.
     
    Skibob likes this.
  20. Frontporch

    Frontporch Junior Member

    Joined:
    Dec 18, 2015
    57
    13
    0
    Location:
    Nj
    Vehicle:
    2007 Prius
    Model:
    N/A
    I took the belt off and the rattle noise was gone. The water pump pulley had a little play in it. Ordered a new water pump ( and plugs and pcv valve... time to catch up on maintenance!!). That video was pretty accurate and pulling the belt was a great quick check.

    Thanks to all for the great ideas. I learned a lot and have a few more tools going forward.
     
    Raytheeagle and Skibob like this.
Loading...