Honda compression failure - help needed!!!

Discussion in 'Mechanic and Repair' started by integrityman, May 20, 2009.

  1. integrityman

    integrityman LawnSite Bronze Member
    Posts: 1,710

    Guys-

    Went to crank up my Honda Harmony. Refused to start. Took apart the carb cleaned it put it back together. Replaced the plug. Still no go. Has good spark and clean air filter. I Took it to the shop and was told the mower has no compression. I have a hard time believing this. It had no prior symptoms, oil burning or hard starts. The failure was sudden.

    The mower is about 7-8 years old and I have no idea how many hours are on it.

    Thoughts????

    I hate to part w/ my H\onda Harmony- been a good mower and very reliable.
     
  2. mowerknower

    mowerknower LawnSite Senior Member
    Posts: 766

    Could have blown a rod or dropped a valve.
     
  3. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Posts: 2,231

    Pull the valve cover and check to see that both push rods are in place and that the valves are both opening/closing properly. It's possible that a valve(most likely the exhaust) has stuck in an open position and if that is the case the push rod has likely fallen out of position as well. A leakdown test can be done to determine the source of the leak. It's rather surprising that the shop didn't at least pull the valve cover for a more definitive answer for you. One can do a poor mans leak test by bringing the piston to top dead center, remove the spark plug and apply slight air pressure to the cylinder through the spark plug hole. It is best to remove the recoil start assembly use a socket on the flywheel nut to prevent the air pressure from pushing the piston back into the cylinder. If you hear air escaping from the exhaust the exhaust valve is stuck open or not seating properly. Air escaping from the carburetor air horn indicates a leaking intake valve. Air escaping from the crankcase breather would indicate worn rings although this condition is best verified with a leakdown test tool where air pressure in the cylinder is more controlled.

    Dutch
     
  4. integrityman

    integrityman LawnSite Bronze Member
    Posts: 1,710

    Thanks Dutch.
     
  5. topsites

    topsites LawnSite Fanatic
    Posts: 21,654

  6. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Posts: 2,231

    A simple compression tester will definitely let you know whether or not you have compression. On the other hand, a leakdown tester will help in diagnosing where the source of the leak is without teardown. Several of the engine manufacturers have them available but they are a little pricy in my opinion, particularly for the occasional user.

    Dutch
     

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