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Water Loss - Shouldn't be a porous head though

Discussion in 'A3/S3/Sportback (8P Chassis)' started by danb986, Jul 7, 2012.

  1. danb986
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    danb986 In awe of VCDS

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    I know what you're thinking; 2.0 TDI with a BKD engine, it could be the dreaded porous head.
    But mine is a 2007 with a code C cylinder head. As far as I understand (and from what the Audi parts guy said when I was buying coolant) the porous head issue only affected early 2.0 TDI engines with an A or (less commonly) B cylinder head code.

    It's lost about a litre over the last year, but now it's lost about an inch this week (200 miles) from the expansion tank. It starts and runs fine though.

    I can't see any water where I park, but the undertray and never ending rain might be masking it.

    I thought maybe a faulty tank cap could be leaking vapour, but the Audi parts guy said he'd never sold any of these so it's unlikely. Is there any way I can test this, or is this an unlikely culprit?

    I also thought it could be the EGR cooler as this seemed common after a bit of Googling, but I remember Nige saying once that these aren't usually the cause, so I want to avoid spending £350 on something that's not faulty.

    Apparently another common one is the radiator, but I don't think there's anything dripping and I don't know which bit is the usual spot for leaks. I thought even a tiny pin prick hole in a rad would cause a jet of water to spray out.

    Is a leak of this quantity likely to leave a puddle on the floor, or would it just evaporate?

    Can anyone suggest what's the most common cause of leaks so I can narrow down my searching. It's driving me crazy, so if anyone can suggest anything I'd be really grateful. :sorry:
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  2. mike foster
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    mike foster Fossie

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    Could possibly be a head gasket. Never actually heard of that problem before on a BKD but you never know.

    Not sure how to test for it either unless VCDS would show silly figures in engine measuring blocks - sorry !
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  3. Geraldy212
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    Geraldy212 Sportback owner

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    Dan, make sure that you look for leaks immediately after turning off the engine, having waited until the engine reaches its full operating temperature. That is maximum water pressure, and should show you any external leaks. Also look for stains around water pipe joints and the corners of the radiator. By the way, no BKD engine loses one liter of coolant over a year. It is a closed system after all, so ANY loss needs to be investigated immediately. When the engine is hot (max leaks) the water is also very very hot, and indeed will evaporate quite quickly. A small leak may boil away so fast you may miss it. Go after the joints first, then worry about the water pump and/or gasket. Good luck.
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  4. mjr901
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    mjr901 S3 Pollution Plus+ Edition

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    Have the head pressure tested?
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