Big chainsaw troubles..... help needed

hemlock Posted By hemlock, Apr 10, 2013 at 8:22 PM

  1. hemlock

    hemlock
    Feeling the Heat 2.
    NULL
    

    May 6, 2009
    455
    7
    Loc:
    east coast canada
    Hello,
    It looks like my Husky 365 just bit the dust, and I can't figure out what happened. It was cutting along just fine, then sputtered, rattled and died. Tried to pull it over, and there was nothing. The compression is completely gone (gage reads almost zero). It was not straight gassed. The only thing I can think of is an air leak some place, but it did not feel or sound lean. What else might have caused this? Any help would be great. I think I'm about to cry. Thanks
     
  2. arngnick

    arngnick
    Member 2.
    NULL
    

    Feb 15, 2013
    245
    28
    Loc:
    Mansfield, PA
    How new is the saw? I had a buddy that the same thing happened to him during the first year of owning the new saw. The dealer blamed it on old gas with ethanol in it. I think the reluctantly covered it onder warranty.
     
  3. Ashful

    Ashful
    Minister of Fire 2.
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    Mar 7, 2012
    8,970
    3,742
    Loc:
    Philadelphia
    Rattle? No compression? sounds like a broken connecting rod.
     
  4. hemlock

    hemlock
    Feeling the Heat 2.
    NULL
    

    May 6, 2009
    455
    7
    Loc:
    east coast canada
    Thats what I thought - but when I removed the plug and pulled it over, the piston was moving.
     
  5. Nixon

    Nixon
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    Aug 6, 2008
    698
    459
    Loc:
    West Sunbury ,Pa.
    Pull the muffler and see what the piston looks like. You may have torn an intake boot ,or lost a crankcase seal .
     
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  6. MasterMech

    MasterMech
    Guest 2.
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    +1 on pull the muffler. Broken ring? Husky is still a single ring design no?

    Check the decomp valve?
     
  7. hemlock

    hemlock
    Feeling the Heat 2.
    NULL
    

    May 6, 2009
    455
    7
    Loc:
    east coast canada
    Pulled off the cylinder, and everything looks pretty good. Is it likely a crankcase seal?
     
  8. Ashful

    Ashful
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    Mar 7, 2012
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    Just so we're not making any wrong assumptions, how exactly did you test compression? Be specific.
     
  9. MasterMech

    MasterMech
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  10. hemlock

    hemlock
    Feeling the Heat 2.
    NULL
    

    May 6, 2009
    455
    7
    Loc:
    east coast canada
    With a gauge. Pulled it over a few times. It hardly blew anything.
    Master Mech - I'll check the decomp.
     
  11. HittinSteel

    HittinSteel
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    Aug 11, 2008
    1,587
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    Loc:
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    Good news on the piston! Now you just have to find where its getting air.

    Isn't compression made above the intake and exhaust ports? If so, what else could it be besides decomp, spark plug hole, cracked cylinder, stuck ring, ??????

    I had the same situation on a saw I compression tested for a guy. Showed nothing on the gauge. Pulled the muffler and the piston and rings were in great shape. It stumped me (and he didn't leave the saw with me for further investigation).
     
  12. thewoodlands

    thewoodlands
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    Aug 25, 2009
    10,825
    2,930
    How's your spark splug, did it blow out , might need a heli coil.
     
  13. Ashful

    Ashful
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    Mar 7, 2012
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    Loc:
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    That's why I asked how he's measuring compression. If it's not putting any compression on the guage, the spark plug is out of the equation.

    If the decomp valve is good, then it's time to pull the jug!
     
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  14. smokinj

    smokinj
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    Aug 11, 2008
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    "The rattle" Small sound Rings broke Big sound crank?????? Either way air leak is not going to be a rattle. Iam with Joful time to pull the head and hope its rings.
     
  15. cnice_37

    cnice_37
    Member 2.
    NULL
    

    Mar 24, 2011
    55
    5
    Loc:
    Assonet MA
    I'd check to see if the ring moves by using a small screwdriver and pushing it through the open exhaust port (you removed muffler already.) My guess is its stuck, pretty common on these saws I believe.
     
  16. Fiziksgeek

    Fiziksgeek
    Burning Hunk 2.
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    Jan 3, 2012
    138
    30
    Loc:
    Oxford, CT
    My first thought would have been a lean seizure.
     
  17. hemlock

    hemlock
    Feeling the Heat 2.
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    May 6, 2009
    455
    7
    Loc:
    east coast canada
    Put the cylinder back on and checked the decomp valve and it is also good. Guess I'm bringing it to the dealer. It makes no sense at all. Everthing that would cause a compression issue checks out, but it has 0 psi. I'm thinking something else is going on. This is out there, but could the flywheel be turning on the crank, and with the plug/gauge in, it creats just enough back pressure to cause the flywheel to turn on the crank, but with the plug/gauge out, it allows the piston to turn over, due to no back pressure? It's a stretch, but it all makes no sense otherwise.
     
  18. MasterMech

    MasterMech
    Guest 2.
    NULL
    

    Pretty easy to yank the flywheel and look for a sheared key. Or just mark it and pull it over, recheck the marks.
     
  19. Nixon

    Nixon
    Minister of Fire 2.
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    Aug 6, 2008
    698
    459
    Loc:
    West Sunbury ,Pa.
    Is that going to address the 0 compression ? Seems like a real mystery ..... 0 compression ,good decomp and plug , good P/C and rings .
     
  20. MasterMech

    MasterMech
    Guest 2.
    NULL
    

    But Hemlock makes a good point that the flywheel could just be spinning on it's taper. If it ain't rings, piston, cyl, decomp or spark plug, I'm open to slightly more exotic theories. ;hm
     
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  21. cnice_37

    cnice_37
    Member 2.
    NULL
    

    Mar 24, 2011
    55
    5
    Loc:
    Assonet MA
  22. hemlock

    hemlock
    Feeling the Heat 2.
    NULL
    

    May 6, 2009
    455
    7
    Loc:
    east coast canada
    Thats what it is. I feel like an idiot. I marked the flywheel to the nut, gave it a pull as though starting, and the flywheel is spinning on the crank. When you pull it over slowly or remove the plug, it grabs the crank and turns. Thing is, is this good or bad - and can it be fixed? Does anyone know the torque spec for the nut?
     
  23. basod

    basod
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    Sep 11, 2009
    937
    351
    Loc:
    Mount Cheaha Alabama
    Is the flywheel keyed to the shaft? If not the timing mark will matter.
    If you figure that out remove the plug and use a piece of clothesline stick down in the plug hole this will prevent engine turning over during tightening

    What size is the nut? rather the shaft thread(it's somewhere in the 1/2,9/16,5/8,3/4- ball bark standard size. Just close doesn't matter if metric
    I'd assume it's fine thread as well. could be anywhere from 90-200ft-lbs (though probably newton-meters)

    Definitely use some red(higher temp) threadlocker or similar when reinstalling
     
  24. Ashful

    Ashful
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    Mar 7, 2012
    8,970
    3,742
    Loc:
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    Definitely ignore anyone's home-grown ideas, and definitely follow the procedure in the shop manual.
     
  25. hemlock

    hemlock
    Feeling the Heat 2.
    NULL
    

    May 6, 2009
    455
    7
    Loc:
    east coast canada
    I put the flywheel back on (you can still see where the key was), and torqued it down, and it fired up. My question now is - is the key critical for power transmission, or is it strictly for timing? My guess would be that being a tapered shaft, that the key is primarily for timing but still am not certain. The key was cast right into the flywheel.
     

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