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loud blowing noise coming from engine when started up......?

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by rockstar, Oct 15, 2007.

  1. rockstar
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    rockstar Member

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    [Oct 15, 2007]
    Hi anyone any idea whats up with the car,when i start the car up i hear a loud fan/blowing noise coming from the engine area,sounds like a hair drier on full blast! having opened the bonnet i found air to be blowing from the front of the engine,around where the belt is being spun round,(maybe coming from the motor part itself that drives it??)its like as said a hairdrier on full blowing cold ish air,having turned engine off and back on fixes it,ive noticed it doing it most times i have started the car but not always......is it a faulty sensor and what the air thing thats blowing,it stays on for about 2-3 secs after i turn engine off aswell...

    Any ideas...thanks
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  3. golf
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    golf ***** rent boy VCDS Map User

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    [Oct 15, 2007]
    Again, I'll ask people to specify their car before describing symptoms.

    From what you've described it sounds like the secondary air pump, the noise is quite normal on cold starts and the unit is probably working fine.
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  4. rockstar
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    [Oct 16, 2007]
    Hi car is 1.8t quattro, sounds like a really loud hairdrier blowing.....but having had the car a few years now ive never noticed it do it,which makes me think its a fault,when ive started the car and it is making the noise if i immedialty stop it and restart the engine it stops...? has happened a couple of times today even after being out driving and the engine being warm already,

    Checked under the bonnet while it was doing it and put my hand over the area the noise is coming from,there is a strong blow of air coming from the front of the car behind the radiator from the part that is driving the a belt (is this a motor?)

    .......it may also have kicked in while out driving,tried to listen to engine at traffic lights today with window down and im convinced it was again making the noise again after not being on,i switched the engine of and back on this made it stop.....cant be 100% sure it was as it was noisey with other traffic but am 90% + sure it was......

    is it a faulty sensor or other part on its way out......?
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  5. Elberoth
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    [Oct 16, 2007]
    SAI - secondary air injection
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  6. rockstar
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    [Oct 16, 2007]
    drove it before on start up from cold this morning it never kicked in right away,but after driving 10 secs or so it started and continued till i stopped when i turned the engine off about 5 mins later......is this quite normal then?,cos having had the car 4 years ive never noticed it before ..ever? maybe paranoia is setting in but is like a jet engine when is blowing......very loud!

    what exactly is secondary air injection/ what does it do it for? thanks
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  7. golf
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    golf ***** rent boy VCDS Map User

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    [Oct 17, 2007]
    Well, it shouldn't be noticably loud, it's a slight hum and when it comes the revs will drop ever so slightly.

    If the noise is quite loud then it could maybe be your auxiliary fans on. When these come on you'll know about it though, as they are extremely loud.
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  8. rockstar
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    [Oct 17, 2007]
    extremely loud? sound like a loud hoover or a jet engine even!,as this does....?
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  9. golf
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    golf ***** rent boy VCDS Map User

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    [Oct 17, 2007]
    If you want responses, please write in legible English.
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