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Strange starting problem fixed????

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by Vag_Man, Apr 4, 2013.

  1. Vag_Man
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    Vag_Man New Member

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    [Apr 4, 2013]
    This is a strange one. my car for a while now has not liked the frozen morning starts. it used to start and then judder for a few seconds chuck out loads of white smoke and eventually settle down after about 3-5 seconds. i thought this might be down to glow plus temp sender etc usual suspects. anyway this didn't bother me too much as the car always started and once it had been started was fine all day.

    i did however have a leaking rocker cover gasket from the back corner. now the only way this is fixed according to Audi is to buy a whole new rocker cover complete with gasket, this is a lot of money that i did not want to spend as you can get a replacment gasket from GSF for about £12 but apparently its not quite the right thickness so again can leak.

    so i decided to remove my rocker cover and inspect. the gasket to my eyes was intact no problems. It may have squashed up over time.. so i decided to use some ThreeBond sealer. coating this thinly on the gasket and a little on the well known problem areas around the cam casing. back left mainly as this is known as a problem area.

    anyway you may be wondering what this has to do with my starting problem. well...................................

    i replaced the rocker cover complete with ThreeBond sealed gasket and the oil leak seems to have been sorted. but also now in the morning even though we have had a couple of mornings when the temperature outside has been in a minus. my car has started perfectly. no judder no smoke.

    now i might be being stupid here but i have the exact same car as my brother a 2001 A6 115PD SE. he had the same starting problems and he also had a leaking gasket we did both cars over the weekend and now both are starting better when cold.

    is this a coincident or has sealing the gaskets stopped air getting in somewhere. its puzzled me and my brother.
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  3. eamo
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    eamo New Member

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    [Apr 5, 2013]
    i have the exact same problem on my 03 ake engine 180bhp allroad. my friend has a 05 2.0tf 140bho a3 with the same problem too. what exact sealant did you use?
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  4. Vag_Man
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    Vag_Man New Member

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    [Apr 5, 2013]
    its called 'threebond' that's the original name. But the company also make the same stuff for yamaha and call it yamabond. Both are the same. It's good stuff. But don't be tempted to chuck loads on thinking its better. It just needs a thin layer.
    hope this helps.
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  5. myth
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    myth Member

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    [Apr 9, 2013]
    It's not a coincidence. You are about right, but I don't know how much fake air you can get through that.

    During the detonation cycle, the gases pushes the pistons down, right? But between the piston and the cylinder, there are 3 segments for sealing. Even in a new engine, that segments doesn't 100% seal the gases from passing right between the piston and the cylinder. Those gases(called non-burned gases) end up in the engine itself and has to be evacuate somewhere. But because of the pollution, they are sucked back into the intake manifold right between the MAF and turbo.

    If the engine is not fully sealed, more unmeasured air gets into the engine.

    You can test this on a petrol engine(because the petrol needs exact amounts of A/F ratio to run smoothly) by removing the oil cap and notice how the engine noise changes, because the engine is getting more air and the MAF doesn't read the correct amount.

    Diesels can run lean or rich but I don't think it matters that much. Even if you remove the oil cap, the engine doesn't really feel the difference.
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