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Compression Readings

Discussion in 'A3/S3 Forum (8L Chassis)' started by metricspaces, Apr 10, 2009.

  1. metricspaces
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    metricspaces Member

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    [Apr 10, 2009]
    I just got some compression readings done on my cylinders of my 1999 Audi S3 (210BHP APY Engine) and I was wondering how they compared to others on here? Here are my results:

    No 1: 1200 PSI
    No 2: 1150 PSI
    No 3: 1150 PSI
    No 4: 1150 PSI

    Do these figures seem OK?

    Does anyone know what readings they would have come out from the factory?
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  3. metricspaces
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    metricspaces Member

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  4. ash_pearce
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    ash_pearce Member VCDS Map User

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    [Apr 12, 2009]
    are you sure you have the figures right? 1150 psi is 79 bar, no way! are you messuring in kPA instead of psi?

    Apart from the high numbers all the cylinders are balanced well. The bentley manual suggests anywhere between 144 and 190 psi. Ideally all within 10 % of each other.

    Check you figures and get back to us.
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  5. metricspaces
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    metricspaces Member

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    [Apr 15, 2009]
    These are the figures I got from my mechanic who did the test for me. He didn't seem to think there was anything abnormal about the figures. So I was just checking on here to see if they matched what others were getting.

    Bit worried now! I think I need to go back to him and let him know the ranges you got from the Bentley manual (144 and 190 psi) and ask him why mine aren't in this range?

    The car seems to be running fine, so I'm hoping it's just a problem with how he measured it.
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  6. ash_pearce
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    ash_pearce Member VCDS Map User

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    [Apr 16, 2009]
    I would go back to a mechanic that gives you readings like that. Whats the reason for the compression check anyway?
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  7. metricspaces
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    metricspaces Member

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    [Apr 16, 2009]
    My car burnt about 1 litre of oil in 1500 miles. This seems quite a lot to me! So I got him to check the compression readings to see if there may have been any leaks in the cylinders. I also got him to check past the turbo, to see if there was any signs of oil leaking past it.

    The mechanic didn't seem to think the car was burning oil, simply that it was "using" oil.

    I've searched the forum for other posts about oil usage. Some seem to be as bad as mine. Some seem to use no oil at all.

    But to me, it seems like a massive amount of oil to be using as I do between 10,000 and 15,000 miles a year. That means over 10 litres of oil a year. I'm using Castrol Edge 5w-30, which is quite expensive, so over a year it'll be really expensive :(
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  8. ash_pearce
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    ash_pearce Member VCDS Map User

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    [Apr 16, 2009]
    It does seem alot, any oil on the tail pipes?

    How many miles you done? Might be worth trying a slightly thicker oil. 5w- 30 is pretty thin, you'll get mixed answers on what oils to use but 10w - 40 is always a safe bet.
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  9. metricspaces
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    metricspaces Member

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    [Apr 16, 2009]
    Your hunch on the readings being kPa seems good as 1 kilopascal = 0.145037738 PSI.

    If the 1200 reading I was given was kPA then that would give me 174 PSI.

    This would be within the range you have from the Bentley manual (144 and 190 psi).
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  10. metricspaces
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    metricspaces Member

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    [Apr 16, 2009]
    By tail pipes, do you mean the exhaust tips? I've had a look a few times, they are pretty black, but the car is 10 years old so it doesn't seem that unusual? I couldn't see any signs of fresh oil.

    I went with the 5w-30 as it seems to be the recommended oil.

    It would be nice to know if I have a problem. From reading the forum it would seem that the two main causes would be the turbo going or seals on the cylinders leaking.

    Both of these it would seem would cost a lot of money to fix. So, it may be cheaper to just keep topping up oil!
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  11. ash_pearce
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    ash_pearce Member VCDS Map User

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    [Apr 16, 2009]
    It has to be in kPa, I dont know of another measurement of pressure thats commonly used. 174psi is fine, and they are within 10% of each other.
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    ash_pearce Member VCDS Map User

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    [Apr 16, 2009]
    yeh exhaust tips, in some cases they can be wet with build up of oil. any blue smoke when driving? Its more likly to be the turbo seals than the cylinders. How many miles you done?
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  13. metricspaces
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    metricspaces Member

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    [Apr 16, 2009]
    No blue smoke whilst driving. The car is up to 77K miles now, which isn't mad high for a 10yr old car.

    The mechanic said he checked past the turbo and saw no signs of oil. Others on here that had turbo problems said they checked past the turbo and saw signs of a lot oil. So, hopefully I'm OK there?
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  14. ash_pearce
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    ash_pearce Member VCDS Map User

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    [Apr 16, 2009]
    I dont think you have anything to worry about then, if your still concerned maybe take it somewhere else for a second opnion. You've got good compression and no smoke, looks like you just have a thirsty one.
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