Tearing down a compressor
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  1. #1
    Join Date
    Feb 2004
    Posts
    126
    Any of yall run into this much. Tore down 2 Copeland K body compressors this week. We got slow so I got bored and started tearing them down to see what was wrong. One was 2 years old and the discharge port on the valve plate had blown into many pieces. One piston was coming out of the hole also. It had very black oil in it...may have gotten just a tad warm I think.

    The second compressor was about 15-20 years old and I was 110% sure it had a broke rod in it from listening to it. Well it didnt. All the reeds were bent upwards just a itsy bit. Again another one of the pistons on it was coming out the hole. I could put my finger where the piston should have stopped at and it would raise it. Also on this piston you could get a little play in twisting it.

    Just curious if its a common finding when tearing one down.




  2. #2
    Join Date
    Jan 2004
    Location
    Massachusetts
    Posts
    665
    #1 Sounds like it got hammered with liquid and severe heat
    #2 Sounds like it wore out
    "The value of quality is long rembered after the thrill of low price is forgotten."

  3. #3
    Join Date
    Sep 2001
    Location
    East Stroudsburg, PA
    Posts
    13,215
    Yeah, they're both common problems with "K" bodies and "E" bodies.

    Being air cooled, they're susceptible to damage from excessive heat, and they slug very easily, as opposed to the refrigerant cooled models, which take quite abit more abuse. (The 3D Copelands notwithstanding. )

    I ALWAYS pull the head on an out of warranty K or E before condemning the entire pump. I've found lots of broken valves, replaced them, and sent her off running again. Next to no callbacks after doing this, also.

    Just remember to fix the problem, not the compressor. (Find out what caused it, and straighten that out ASAP, and these compressors last forever.)

  4. #4
    Join Date
    Mar 2004
    Location
    South
    Posts
    51
    Sounds like they were both slugged. Some "E"s are refrigerant cooled, but all "K's are air cooled. Small compressors are air cooled to avoid the loss in capacity you suffer from heating the return gas before it gets to the cylinder. Also, small suction cooled compressors will run very high discharge temps when running low temp.

    As far as piston clearence, don't forget about the valve plate gasket. The piston is machined with a reed relief slot so it can rise slightly above the deck at TDC and fill the re-expansion volume that the gasket would normally create. The reed relief gives the suction reed a place to hide.

  5. #5
    Join Date
    Feb 2003
    Posts
    1,166
    Seen a lot of these out there with no safties installed. does'nt hurt to install low & high pressure safety's when repairing or replacing.
    Watts New, Ohm My, I been Electrically Commutated. Are U2.

  6. #6
    Join Date
    Jun 2001
    Location
    Michigan
    Posts
    12,077
    Saftey's. I'll write that down..

  7. #7
    Join Date
    Feb 2004
    Posts
    126
    Safeties? You want them installed? Sheesh....most of them are installed but usually dont work or are not adjusted correctly.

    Oh and the 2 year old compressor we tore down I have nto seen a reason for slugging. Now the fact the thermostat was turned wide open and never cutting off may have been a factor, thus making the time clock the thermostat. Hoping the thermostat is all it was.

  8. #8
    Join Date
    Mar 2004
    Location
    Lombard IL
    Posts
    171
    you would think the protection would be a factory thing?

  9. #9
    Join Date
    Feb 2004
    Posts
    126
    Most new Copeland condensing units come with a low pressure switch on it.

  10. #10
    Join Date
    Feb 2003
    Posts
    1,166
    If I recall right ya dont get them on those Hussmann UML's.
    Guess I thought I was looking at Hem's post on the Hussmann unit.

    [Edited by mccool on 03-14-2004 at 11:35 PM]
    Watts New, Ohm My, I been Electrically Commutated. Are U2.

  11. #11
    Join Date
    Dec 2002
    Location
    davenport, iowa
    Posts
    778

    Question

    you might try pulling out the pistons and check the rods; the wrist pin hole is probably wearing out (elongated) which will allow the piston to travel up/down more than normal, i believe the cause is lack of lube from low suction gas velocity,short cycling, liquid refrigerant pulling out too much oil on start up,etc.
    Da Threadkilla

  12. #12
    Join Date
    Nov 2013
    Location
    Broken Arrow, OK
    Posts
    14
    Piston wear at wrist pin at the latter could be the compression ratio was a little high over a long period. Look at the piston wear. Worn skirts show lack of lube.

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