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Thread: whats that noise? Update: Alternator bearing

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    whats that noise? Update: Alternator bearing

    https://youtu.be/qeWP75IKYfc

    any idea what the higher pitched noise is?

    2015 mirage hatchback 70k miles. the main belt is taught and not cracked or rotted.



    Update: Fixed!

    Quote Originally Posted by benwerks View Post
    mission success. it was a bearing in the alternator pulley. pulled the alternator out in front of the shop this morning they had a new pulley on there within an hour. driving around now noise is gone.

    alternator removal and reinstallation difficulty 2/5

    also I replaced the serpentine belt with the RockAuto replacement



    Last edited by Eggman; 08-20-2019 at 08:46 AM. Reason: Added solution

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    Senior Member Dirk Diggler's Avatar
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    Quote Originally Posted by benwerks View Post
    https://youtu.be/qeWP75IKYfc

    any idea what the higher pitched noise is?

    2015 mirage hatchback 70k miles. the main belt is taught and not cracked or rotted.
    Ive heard that same noise too, albeit much lighter and only occasionally. Its been a couple of weeks since Ive heard it.

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    Senior Member Dirk Diggler's Avatar
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    Ask Fummins. He's a huge help around here.

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    Moderator Eggman's Avatar
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    Quote Originally Posted by benwerks View Post
    https://youtu.be/qeWP75IKYfc

    any idea what the higher pitched noise is?

    2015 mirage hatchback 70k miles. the main belt is taught and not cracked or rotted.
    Hello benwerks and welcome to the forum.

    I can't say I've heard a noise like that out of my 2015. Is sure sounds like the accessory belt. At least that sound is isolated to the engine and there is no need to wonder if it is related to any other part of the drivetrain. Your engine turned over fast, so I rather doubt it's a failing battery - one that would put a strain on an alternator.

    So, when did you first notice this? What other checks have you made? How is your A/C? I'm guessing you have a CVT? Feel free to make a forum Garage entry. The link can be found to the left-hand column next to your post.

    Garage empty: add car

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.9 mpg (US) ... 21.2 km/L ... 4.7 L/100 km ... 59.9 mpg (Imp)


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    Quote Originally Posted by Eggman View Post
    Hello benwerks and welcome to the forum.

    So, when did you first notice this? What other checks have you made? How is your A/C? I'm guessing you have a CVT? Feel free to make a forum Garage entry. The link can be found to the left-hand column next to your post.

    Garage empty: add car
    thank you. i noticed this noise 2 or 3 days ago after running half a tank of premium. the a/c works and doesnt really change how the noise sounds. i havent made any other checks and its actually a 5 speed.

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    To me it sounds like the timing chain being a little tighter than usual. Nothing to worry about!

    The chain has its own little tensioner with a built-in sort of ratchet to prevent it retracting without oil pressure. Initially the oil pressure pushes the tensioner piston firmly forward and tensions the chain. To prevent a loose-chain-noise on start-up happening before oil pressure has been achieved, the tensioner piston has a simple ratchet-type mechanism that rests in one of several parallel grooves on the side of the piston. With normal chain wear, the tensioner piston moves outwards a little bit more to compensate the now longer chain and keep up its tension.
    Maybe the tensioner has just moved a groove further out than before, resulting in a somewhat tighter chain producing that noise. Nothing to worry about at all, totally normal.

    You can easily check it on a cold engine by taking off the oil-filler cap and pressing onto the chain with a finger. It will feel tight, not the least loose at all.
    In time normal wear will lengthen the chain and that noise will disappear. If you would then press on that chain, you would feel it being a tiny bit loose. In time, the tensioner will go another groove forward to compensate wear, and the same will happen again.

    We can be truly happy our cars have that anti-return mechanism. I had a Nissan that did not have that feature, and the grating noise of the chain during and shortly after startup sounded absolutely frightening.
    Last edited by foama; 08-14-2019 at 12:58 PM.

  7. The Following User Says Thank You to foama For This Useful Post:

    Eggman (08-14-2019)

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    Senior Member Fummins's Avatar
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    I haven't heard that one on a Mirage before. Almost sounds like an old ford power steering pump. Hopefully foama is right.
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    Optima

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    Still Plays With Cars Loren's Avatar
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    Check the accessory belt tensioner. A failing bearing there could make a noise like that.
    Simplify and add lightness.

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    Quote Originally Posted by Loren View Post
    Check the accessory belt tensioner. A failing bearing there could make a noise like that.

    It does sound like a bad bearing. It's actually quite similar to the failing AC clutch bearing on my wife's 2014 Equinox. 56k miles and needs a new compressor. Gotta love GM.

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    Senior Member dspace9's Avatar
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    Quote Originally Posted by benwerks View Post
    thank you. i noticed this noise 2 or 3 days ago after running half a tank of premium. the a/c works and doesnt really change how the noise sounds. i havent made any other checks and its actually a 5 speed.
    I'll prolly get flack for this but, don't run premium in a regular octane car.

    I've had my Mirage 5.5 years, it's a 2014, I never sampled with premium gas, always get 43 MPG-- no issues. Motor purrs like a kitten. Experiments like this, well, cars are too expensive. I don't got no extra money.


        __________________________________________

        click to view fuel log View my fuel log 214 Mirage ES 1.2 manual: 39.8 mpg (US) ... 16.9 km/L ... 5.9 L/100 km ... 47.8 mpg (Imp)


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