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how to change spark plugs

Discussion in 'A3/S3/Sportback (8P Chassis)' started by ru4shaw, Mar 7, 2010.

  1. ru4shaw

    ru4shaw Member

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    just doing a service on my car just not to sure on how to change the spark plugs, does anyone know how i get to them i dont want to brake anything. so i just lift the spark plug connectors or do i need a special tool
    i also havent changed the cabin filter so any advice on that would be helpfull
    thanks
     
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  3. Boydie

    Boydie Boycie
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    If you are not confident in doing it, go somewhere or get someone who is. You can easily snap spark plugs when tightening and they can get lodged in the engine.

    You need a special tool to remove them which you can get from halfords

    You need to remove the engine cover, disconnect the coil packs and pull them out one at a time. Use the special plug tool to remove the plugs and then replace them with new ones.
     
  4. warren_S5

    warren_S5 Moderator
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    It's not a job I would do without a torque wrench.

    For a brand new spark plug (never been fitted before so the washer is not compressed), in an alloy headed engine like ours (not a cast iron head), the 14mm thread diameter plugs require:

    18-22lb/ft torque to do them up (25-35Nm). Source: Spark-Plugs.co.uk (here)

    IF you are determined to fit them yourself, and you don't have a torque wrench, then on the box of NGK plugs in my drawer, there is a diagram which shows for newly unfitted plugs that you do the plug up finger tight, then:

    For brand new unfitted plugs: Turn 1/16 of a revolution using deep plug socket / wrench (minute hand from 00mins on a clock face to about 5 minutes past the hour)

    For refitted plugs (post checking): Turn 1/2 to 2/3's of a revolution using deep plug socket / wrench (minute hand from 00 mins on a clock face to between 30minutes - 40 minutes past the hour)

    Whatever method ensure consistency of approach for each plug, and spray a little electrical contact cleaner onto all contact points of plug / coil pack for best quality connection.

    HOWEVER please be mindful alloy heads are made for lightness, and therefore lack the material strength composition of cast alloy. Overtightening may not only cause fatal damage to your engine head, but could cause excessive heat transfer from the block into the plug causing the engine to run erratically, and the plug to be exposed to excessive temperatures during operation (tip failure/overheating of ceramic collar). I know this sounds a bit excessive, and is unlikely, but it's better to know the risks in advance.
     
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  5. Boydie

    Boydie Boycie
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    warren, you have just knocked me down several rungs on my ladder lol makes my explanation look like a 5 years olds essay!
     
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  6. warren_S5

    warren_S5 Moderator
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    If it's any consolation none of it can be claimed as personal knowledge or expertise - all skanked off the web or the side of boxes :readit: !!!
     
  7. KRL

    KRL Member

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  8. ru4shaw

    ru4shaw Member

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    think i explained it wrong im not sure how to remove the coil pack, do i just pull it out one at a time or so i need a tool
    it looks more like you need to twist it slightly but i might be completly wrong
    its a 1.6 fsi by the way
     
  9. warren_S5

    warren_S5 Moderator
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    As per KRL's link...

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  10. ru4shaw

    ru4shaw Member

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    mine looks slightly different would it still work in the same way thought just need to be pulled out
     
  11. warren_S5

    warren_S5 Moderator
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    :yes:
     
  12. MattS3

    MattS3 Active Member

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    Just checking regards the 1/16th turn for new plugs.....if they are flat seated plugs, then it would seem half a turn is required?
    If they are conical, then only 1/16th is required.
    Information here
    Spark Plugs Mobile

    Likewise, the NGK listed for the S3 is a flat type Spark Plugs Mobile

    I'm thinking a torque wrench is safest, like you say.
    But would also be concerned that some might not have used a torque wrench and subsequently got loose plugs.
     
  13. warren_S5

    warren_S5 Moderator
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    There are a couple of dangers to plug tightening.

    1) over tighten it and you can snap the plug / strip the threads in the head
    2) over tighten and you can get too much heat dissipation from the plug to the head
    3) under tighten and you can lose compression and get blow back

    With new plugs as you say it depends on the seating. I can't remember off the top of my head what washer type the S3 runs, but the tightening regimes are different for conical / flat washers so go by the guidance on the box. Also if you remove the plug and reinsert it (following any inspection), the washer will have been slightly compacted, hence why the torque wrench approach is always safest in my mind.
     
    #12 warren_S5, Mar 7, 2014
    Last edited: Mar 7, 2014
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  14. JohnE

    JohnE 2005 A3 Sport 1.6 FSI

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    I changed mine no probs (although I have owned 23 cars over the years and changed the plugs on most so I wasn't starting from nowhere). The Coil packs are a bugger - you think you are going to break them. I made up a little hook tool from some stiff wire I had about - a coat hanger would probably work. The trick is to try and spread the area over which you're applying the force rather than trying to lever up one end and risk breaking it.

    I'd also check they (the plugs) are due for change - mine were a bit overdue when I did 'em, and I thought it would be a chance to cure the intermittent misfire I had at idle. It didn't, and considering the ones that came out had done >60K they were pristine, so I wouldn't bother unless they are really due a change.
     
  15. MrLapou

    MrLapou Well-Known Member

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    Yip that's exactly the way I do it with cable ties. Except, to avoid buying the special slimline socket, I use a box spanner set.
    Placing a smaller one inside the larger one, to increase the reach.

    It's very important if you can to scrap and clear any debris from the hole before removing the spark plug.

     
  16. MattS3

    MattS3 Active Member

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    Did these early this evening.
    Hardest part was getting the engine cover off, crikey it's a pain in the chuff.

    Not sure if the plugs were bad or not, but here is a picture of them.
     

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  17. warren_S5

    warren_S5 Moderator
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    Don't look untoward
     
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  18. MattS3

    MattS3 Active Member

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    Cheers Warren, that was my thoughts but good to have a second opinion.
    I found the guide good, but also used the link to the golf forum above.

    I had a torque wrench but went with the half turn option as per the golf guide and the ngk box, once I'd finger tightened them.
    It just 'felt' right when I tightened them.
     
  19. RedDejavu

    RedDejavu Well-Known Member

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    me next I belive! Great guide Warren, thanks a million.
     
  20. RedDejavu

    RedDejavu Well-Known Member

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  21. warren_S5

    warren_S5 Moderator
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  23. RedDejavu

    RedDejavu Well-Known Member

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    so best is to stick with NGK PFR7S8EG even when I run stage2+ atm? Thx
     
  24. warren_S5

    warren_S5 Moderator
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    Yes, with the copper cores they have much better conductivity and will run far more consistently. Just get them gapped down a bit before you fit them and they will run a treat.
     
  25. MattS3

    MattS3 Active Member

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    I just went with the NGK ones, as per Warrens previous post.
    Managed to get all 4 from Amazon, delivered for £32.
     
  26. RedDejavu

    RedDejavu Well-Known Member

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    is the gapping nessesary as I dont feel confident to do it myself tbh. Especially for the first time:faint:
     

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