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Head Gasket can of worms???

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  • Head Gasket can of worms???

    Morning all,

    I need to tackle the water leak on my head gasket. If I am honest this job does scare me. Not necessarily from a mechanical point of view, more opening a potential can of worms!

    Current plan:

    Remove head
    Assess if it needs skimming
    Replace valve stem seals
    Refit head.

    Now we all know our cars are getting old and need maintenance and they also throw curve balls.

    1.) What other jobs would you recommend doing while I am in there?

    2.) What should I be scared of prepare myself for? (Cracks in head etc??)

    3.) Rough idea of budget?


    Thanks,

    Steve
    The Perfectionist
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    Audi Class Concours winner Stoner Park 2014, ADI Concours D'Elegance Class Winner 2008, Runner up 2014. Winner, S2Forum Show'n'Shine Billing 2006 & 2008.

  • #2
    How will you assess if the head needs skimming, its false economy not to do it, if you already have it off. Imagine refuting everything and finding it still leaks due to the head being very slightly warped. I suggest you get it skimmed and checked for flatness as it will save tears.

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    • #3
      Originally posted by rustybullethole View Post
      How will you assess if the head needs skimming, its false economy not to do it, if you already have it off. Imagine refuting everything and finding it still leaks due to the head being very slightly warped. I suggest you get it skimmed and checked for flatness as it will save tears.
      Don't know! Probably send it off for inspection. I am not one to scrimp on my S2 anyway
      The Perfectionist
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      Audi Class Concours winner Stoner Park 2014, ADI Concours D'Elegance Class Winner 2008, Runner up 2014. Winner, S2Forum Show'n'Shine Billing 2006 & 2008.

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      • #4
        Replace the valve guides if at all worn, this is the source of most smoke, and once the guides are worn, the seals won't do anything to help.

        You can check the head with a steel rule quite easily, it will be quite obvious if at all warped.

        Replace the coolant hoses and breathers that are difficult to get to when you are in there, better now than having to strip it all off again to fix a water leak.

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        • #5
          When were the timing belt and water pump last changed? Also good time to fit one of James's billet crank pulleys
          sigpic
          1991 Audi S2 3B - 2.5 Stroker engine
          1997 A6 2.5TDi quattro avant - C4
          1976 RD250E / 350LC cafe racer

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          • #6
            Steve,

            I would share your apprehension here sir and certainly agree with the above responses. Not sure if this helps your budget, however it may serve to reduce concerns in encountering the possible unknowns, their impact and total time with the car apart if you did some or all of as follows:

            Before dis-assembly (and hopefully the motor's current condition will allow):
            a) If possible do the compression checks and record them (to try to capture the state of the rings) as there is the chance the coolant can damage them (either due to leaks or during said repair);
            b) Get a spare cylinder-head and have it all done prior; and
            c) If this car is turbo'd, then the hot-side stuff may be in need of attention, I have no idea.

            A serviceable 2nd head and the work involved is not insignificant, but may (current motor and budget permitting) also allow one to more leisurely proceed and perhaps even possibly consider some stage one gas-flow work as the car would not yet be apart, such mods have no reliability penalty, and your motor is more efficient for them. Then, if the current head proved to be fine, bonus! You'd have choices.

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            • #7
              All of the above... i would get the injectors cleaned while they are out and flow tested too. Cheap and easy. New pcv pipe and clean the flame trap if you have it there still
              sigpic

              1992 3b S2 Coupe

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              • #8
                I think I am in a similar situation. On the head doing a full re furb is really the only option IMO, valve guides, seats etc. You can also get it pressure tested prior to refitting. If it's never been off before then there is plenty of meat for a skim and its not expensive, especially if done as part of the re furb.

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                • #9
                  Originally posted by s2driveruk View Post
                  All of the above... i would get the injectors cleaned while they are out and flow tested too. Cheap and easy. New pcv pipe and clean the flame trap if you have it there still
                  Thanks David, already done a couple of years ago when I did the IM repaint. Flowed injectors courtesy of another member.

                  Cheers,

                  Steve
                  The Perfectionist
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                  Audi Class Concours winner Stoner Park 2014, ADI Concours D'Elegance Class Winner 2008, Runner up 2014. Winner, S2Forum Show'n'Shine Billing 2006 & 2008.

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                  • #10
                    Originally posted by montyrs2 View Post
                    I think I am in a similar situation. On the head doing a full re furb is really the only option IMO, valve guides, seats etc. You can also get it pressure tested prior to refitting. If it's never been off before then there is plenty of meat for a skim and its not expensive, especially if done as part of the re furb.
                    Thanks, I am saving up for a local (good) company to refurb the head while it is off. (Assuming it is not badly cracked or has any other serious issues.. )

                    Cheers,

                    Steve
                    The Perfectionist
                    sigpic
                    Audi Class Concours winner Stoner Park 2014, ADI Concours D'Elegance Class Winner 2008, Runner up 2014. Winner, S2Forum Show'n'Shine Billing 2006 & 2008.

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                    • #11
                      Here is what the AAN work shop manual says about distortion of the head.
                      45764-1cb2bf6b1728cd1285176ce2de9e50fa.jpg

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                      • #12
                        Originally posted by s0_big View Post
                        Here is what the AAN work shop manual says about distortion of the head.
                        45764-1cb2bf6b1728cd1285176ce2de9e50fa.jpg
                        Great thanks!
                        The Perfectionist
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                        Audi Class Concours winner Stoner Park 2014, ADI Concours D'Elegance Class Winner 2008, Runner up 2014. Winner, S2Forum Show'n'Shine Billing 2006 & 2008.

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                        • #13
                          The head on my car is at the minimum skimming thickness as per the book and probably doesn't have any skimming meat left on it. Ive no idea how many times it had been skimmed as it wasn't my original head.

                          When I rebuilt it, I was concerned about the valves getting close to the pistons in TDC and did a lot of testing to verify. I test installed a solid lifter to remove any doubt over valve lift with a partially filled hydraulic tappet and laid a plasticine snake over the valve area on my piston. Turning engine over twice to make sure I hit TDC with valve open and look at the squish in the plasticine... There was plenty of space left there so I pressed on and installed it.

                          What appears to be the issue with max head skimming is aligning the static timing marks in rebuild. I ended up getting a tommi's billet cam pulley and had to apply 4 degrees to get everything lined up. Can't remember if it was + or - degrees but it was definitely 4.

                          If your head isn't warped, think carefully about what ends up being taken off. There is no reason it would be warped unless it has been catastrophically overheated or not bolted down properly.

                          A smooth finish is best for sealing so seek more of a polish than skim. If there is such a thing.


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                          • #14
                            As far as I know the head has never been off. My car only has two previous owners, so I think I can be almost 100% certain this will be its first opening. I am going to take my time and probably send it here for evaluation and refurb:

                            http://www.robwalkerengineering.co.uk/

                            The Perfectionist
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                            Audi Class Concours winner Stoner Park 2014, ADI Concours D'Elegance Class Winner 2008, Runner up 2014. Winner, S2Forum Show'n'Shine Billing 2006 & 2008.

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