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  1. #1
    rackrookie is offline Regular Member - bad email address Contact the Admin
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    Semi-hermetic head leak

    Is it possible for a semihermetic compressor to develop momentarily a leak in the valve plate / cylinder head junction, as it tries to compress some liquid refrigerant (liquid was returning due to a iced-up evaporator)? I think I saw this happening today. Later on, I checked for the leak, and it didnīt show up, that is why I believe it was some kind of momentary leak.

  2. #2
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    How did you chect for the leak? what may have happened was excessive liquid in the crankcase.If you blow a head gasket or break a valve, its going to stay broke.

  3. #3
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    Quote Originally Posted by rackrookie View Post
    Is it possible for a semihermetic compressor to develop momentarily a leak in the valve plate / cylinder head junction, as it tries to compress some liquid refrigerant (liquid was returning due to a iced-up evaporator)? I think I saw this happening today. Later on, I checked for the leak, and it didnīt show up, that is why I believe it was some kind of momentary leak.
    Why do you say this?

    What happened that made you think it was a momentary leak?


    Depending on the type of compressor (air or refrigerant cooled) liquid floodback most likely would manifest itself in a couple of different ways - typically neither resulting in a momentary leak.

  4. #4
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    Quote Originally Posted by rackrookie View Post
    Is it possible for a semihermetic compressor to develop momentarily a leak in the valve plate / cylinder head junction, as it tries to compress some liquid refrigerant (liquid was returning due to a iced-up evaporator)? I think I saw this happening today. Later on, I checked for the leak, and it didnīt show up, that is why I believe it was some kind of momentary leak.
    I've never heard of a momentary leak. it leaks or it dosent.
    I love the smell of phosgene first thing in the morning:

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  5. #5
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    Quote Originally Posted by rackrookie View Post
    Is it possible for a semihermetic compressor to develop momentarily a leak in the valve plate / cylinder head junction, as it tries to compress some liquid refrigerant (liquid was returning due to a iced-up evaporator)? I think I saw this happening today. Later on, I checked for the leak, and it didnīt show up, that is why I believe it was some kind of momentary leak.
    rack,

    We need more info on this compressor, a model number would help. If an air cooled compressor tried to compress liquid, the valves and gasket would see about 10,000 psi pressure. This would blow a head gasket, if your lucky, or a reed, piston or rod. It would be hard to flood a refrigerant cooled compressor unless you have extreme floodback. The motor heat would most likely boil off the liquid refrigerant.

    I suspect you have an air cooled compressor. If its still pumping properly after you repaired the iced up evap, the gasket is probably blown but not showing leaks due to the lower pressure. Pull the head and check it out.

    As others on this post have said, a momentary leak is not likely.

  6. #6
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    Apr 2007
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    Leaks

    It Leaks or it don'nt???? Follow the advice of these PROS....If It LEAKS it leak, It just might take a pressure change to find

  7. #7
    rackrookie is offline Regular Member - bad email address Contact the Admin
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    Thak you all for your interest.

    The compressor is indeed an air cooled semi-hermetic 27 HP Copeland Discus, installed in a low temp R-22 rack. The reason why I called it a "temporary" leak is because as the compressor was getting some liquid refrigerant (a lot of frost covering the body), I thought I saw a stream of gas coming out of the valve plate / cylinder head junction area. It even left an oil mark there. After I while, I came back to take a closer look, applied some bubbles to the working compressor, and nothing showed up.
    I think I am going to follow your advice and remove the head, plate and gaskets for an internal inspection. By the way, Iīve heard that some techs like to soak the new gaskets in compressor oil before usage. Some other techs donīt. What is your opinion?

  8. #8
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    Quote Originally Posted by rackrookie View Post
    Thak you all for your interest.

    The compressor is indeed an air cooled semi-hermetic 27 HP Copeland Discus, installed in a low temp R-22 rack. The reason why I called it a "temporary" leak is because as the compressor was getting some liquid refrigerant (a lot of frost covering the body), I thought I saw a stream of gas coming out of the valve plate / cylinder head junction area. It even left an oil mark there. After I while, I came back to take a closer look, applied some bubbles to the working compressor, and nothing showed up.
    I think I am going to follow your advice and remove the head, plate and gaskets for an internal inspection. techs donīt. What is your opinion?
    rackrookie,

    The 27 HP Discus would be a 6DL3-270E (3 head) refrigerant cooled compressor. Used in a low temp R-22 application it should also have Demand Cooling, liquid injection near the motor below the center head. The heads of a discus are 100% high pressure gas. The valve plate is hollow and is low pressure (suction) gas.

    Now that we know what you have, where was frost covering the body, on top of the compressor or the motor end? Demand cooling injects liquid in the suction cavity, after the gas has passed through the motor. Maybe the DC is malfunctioning and injecting too much liquid. I would check this out.

    If you saw gas leaking and an oil mark, your doing the correct thing by removing the head and inspecting the gaskets. Hopefully you don't have valve damage.

    Good luck and let us know what you found.

  9. #9
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    Quote Originally Posted by rackrookie View Post
    Thak you all for your interest.

    By the way, Iīve heard that some techs like to soak the new gaskets in compressor oil before usage. Some other techs donīt. What is your opinion?
    I have always been told that one should never oil the gaskets. However - I have had great success in using Nylog to seal everything up.

    B-

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