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  1. Weird grinding noise on cold start 
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    I seem to have developed a grinding noise that only happens when it’s cold weather here in London. It goes away when it’s off the choke and warmed up.

    I’ve attached a video to YouTube here A4 B5 2.8 grinding noise on startup - YouTube

    It started soon after my mechanic replaced the valve cover gaskets.

    I have a 1999 2.8 Quattro Avant auto engine ACK.

    Any suggestions?

    Thanks in advance!



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  2. Re: Weird grinding noise on cold start 
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    take the car back to your mechanic.
     
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  3. Re: Weird grinding noise on cold start 
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    He’s retired now, so not an option. Just looking for an opinion on what it might be rather than spending the £60 on getting a dealer diagnostics or tearing the head apart for no gain.

    Thanks!


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  4. Re: Weird grinding noise on cold start 
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    You have a choke??

    Starter motor not disengaging?
    Did this forum help you? Help make sure it's here next time! Follow the instructions at the top of the page to make a suitable donation using PayPal .
    1996 A4 B5 (S2) Avant 1.8T (petrol) 150 bhp code AEB automatic with 79,125 kms = 49,450 miles on 30/07/23
    VW T25 Camper, Alfa 33 1.4 ie, 2 Alfa 33's for parts.
     
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  5. Re: Weird grinding noise on cold start 
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    Isn’t there a choke? When the engine is cold it idles at higher revs until it’s warm enough to idle at the correct level. Isn’t that the automatic choke?

    Could be the starter but it slowly goes away and then stops once the engine is warm. Do you think I should replace the starter? Quite a job isn’t it?

    Thanks for the response!



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  6. Re: Weird grinding noise on cold start 
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    During a cold start the electronic fuel injection control system delivers a higher fuel to air ratio (richer mixture), which achieves the same result as what used to be called a choke.

    I was maybe being a bit picky, as the original meaning of "choke" referred to a simple flap which restricted the airflow into the engine ("choking" it), thus creating a richer mixture, and later became any device which delivered more fuel for a given amount of air. This was usually a separate mechanical device operated by hand, and later by a temperature sensitive mechanism, either mechanical or electromechanical, called an automatic choke.

    So I suppose you can correctly refer to the electronic means of enriching the fuel air mixture as a choke, as it does the same thing

    Re. the starter motor, unless someone comes up with another explanation for that noise, I suggest removing it (you may have to remove the alternator and air conditioning compressor as well as the lower engine cover to get to it) to check for damage to both its drive gear and the flywheel ring gear, as well as for the correct operation of the engaging mechanism, which should move freely.
    Did this forum help you? Help make sure it's here next time! Follow the instructions at the top of the page to make a suitable donation using PayPal .
    1996 A4 B5 (S2) Avant 1.8T (petrol) 150 bhp code AEB automatic with 79,125 kms = 49,450 miles on 30/07/23
    VW T25 Camper, Alfa 33 1.4 ie, 2 Alfa 33's for parts.
     
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  7. Re: Weird grinding noise on cold start 
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    Thank you for the explanation. Will now look for diys on starter removal.

    Appreciate your help.


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  8. Re: Weird grinding noise on cold start 
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    With respect I would suggest that the starter motor idea is barking up the wrong tree.
    You state that the noise only occurs since you had work done on the valve cover area, and only shows up when cold starting.
    I would therefore be looking at vacuum hoses in the area that joins fuel and air intake, which may have been disturbed when removing covers and brackets etc.
    A small air leak, for example might show up when the mixture control side of things is requiring max air intake on cold start, this would reduce as the engine warms up to normal idle, it sounds like an air leak to me,in your tube video.
    Alternatively it may be a coincidence that the car had been worked on prior to the noise showing up,and the other thing it might sound like is a dry bearing, which might also quieten as the temperature increases and thins the oil.
    In my opinion, a poor starter not disengaging, would sound much more harsh and consequently start to damage the flywheel and potentially itself to the point of not working at all.
    Could be up the wrong tree myself but thats just my opinion.
    Hope this gives you something else to ponder and is of some help
    Stuart
    A6 2.4 SE (2000)S3 1.8T (2001)80 Coupe 2.3 (1991)
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    80 Coupe 2.6S (1995)A4 Cab 2.4 sport (2002) Another 2.6 '95 coupe in byzanz purple
    '88 type 89 90 saloon kv 5 pot A4 1.8T 2001
     
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  9. Re: Weird grinding noise on cold start 
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    Yes thank you that helps. I should be checking the route from air filter through to throttle body right? Since this is easier I will start there.

    Thanks!


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  10. Re: Weird grinding noise on cold start 
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    That would be one hell of a noisy air leak. It's just as noisy under the car as near the engine. What are you listening to it on, fourrings?

    RH describes it as a grinding noise, which is what I hear on my PC's external stereo speakers, not a whistle.

    I was thinking of the starter motor gear not completely moving away from the flywheel ring gear, so that it just touches it, until it eventually moves completely clear, not necessarily staying fully engaged.

    Other things to check would be belt driven auxiliaries. I'm not sure that any pump or alternator could make that sound, but worth checking.

    Still, it's easy to check the air inlet and various hoses, a stethoscope or a piece of plastic pipe near an ear is useful to pinpoint a sound.

    I don't get the bit about requiring maximum air intake on cold start either. Cold start requires more fuel in proportion to air, not more air.
    Did this forum help you? Help make sure it's here next time! Follow the instructions at the top of the page to make a suitable donation using PayPal .
    1996 A4 B5 (S2) Avant 1.8T (petrol) 150 bhp code AEB automatic with 79,125 kms = 49,450 miles on 30/07/23
    VW T25 Camper, Alfa 33 1.4 ie, 2 Alfa 33's for parts.
     
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