Engine not running right...

Discussion in 'Mechanic and Repair' started by Horsepower Lawns, Jul 16, 2008.

  1. Horsepower Lawns

    Horsepower Lawns LawnSite Member
    Messages: 213

  2. progressivelawncare

    progressivelawncare LawnSite Member
    Messages: 51

  3. mississippiturf

    mississippiturf LawnSite Senior Member
    Messages: 674

    This is an easy one!! Its that bent tail pipe causing your problems. I'm a heart surgeon, I should know!!!!
  4. SLR

    SLR LawnSite Gold Member
    Messages: 3,210

    do not listen to Missisippiturf. It is the main jet filters that will do this sort of damage every stinking time to any engine.
    Fluid Film in gas tank the only remedy,mix @ 5:1 per tank.
  5. Phil G

    Phil G LawnSite Senior Member
    Messages: 844

    Ain't seen anything like that for a l-o-n-g time, neat photos
    atb Phil
  6. Horsepower Lawns

    Horsepower Lawns LawnSite Member
    Messages: 213

    Can I put this stuff in to fix it?

    I don't know if it would work because its for the wall & my cly. wall look good.
    Maybe that stuff and a little J B Weld.

    It should be good as new.

    Does anybody know what would cause this?
    I think the spark plug may have come apart & took out the exh. valve.
    The push rod was off the exh. valve but I don't think thats what did it because the spring is still "good" so it would have closed the valve before it hit the piston.
  7. sawman65

    sawman65 LawnSite Senior Member
    Messages: 754

    this is what kaw will tell ya if you were going to try to warranty this engine. NO WAY!!!! even if it only had 10 hours on it. the reason they claim is because you used bad gas this caused the valve to stick open your fault.and i am not kidding
  8. jkilov

    jkilov LawnSite Bronze Member
    from MS
    Messages: 1,415

    The pics are a bit blurry. Looks like a hole melted into the crown of the piston, spark plug electrode broke off and munched leaving marks on the head. And crankshaft bearings busted due to extreme loads.

    I'm no shop mechanic but all these look like symptoms of detonation (pre-ignition). Since the piston hole is located near the spark plug I'd be thinking the wrong heat plug was used or something wrong with ignition. An obstructed exhaust can also cause this or like someone mentioned gas with low octane (or sitting too long).

    Sorry to bring it to you, I doubt it's worth repairing. Consider a short block or even new engine depending on hours / part prices. Hopefully some reps will take a look and post replies to shed more light on the situation.

    S DIAMOND LawnSite Member
    from South
    Messages: 108

    Your best photos (from the top down, #4,#8, and #10) show the damage the clearest.
    Photo #4 shows burned oil and blow-by in the upper left hand corner, interestingly enough, by the exhaust valve.
    This leads me to believe that the blown gasket, along with possibly a sticky valve, lead to the destruction of the exhaust valve itself, which in turn pulverized the piston and the cylinder head. This went on for who know how long, until it took out the spark plug.

    If this started out with a blown gasket or a smaller problem which lead to a blown gasket, and continued to run, (as indicated by, poorly running with smoke) then it is possible that the leaning fuel mixture did in fact heat up an already distressed valve (bottle necking it) along with the heated and sticky oil in the gallery (valve sticking), causing it to snap when it was hit. The question is, how long did you have a noticeable problem before it got to this point? The leaning mixture indeed could have caused detonation and further enhanced the problem. There are many possible scenarios, but IMHO, the exhaust valve is what took out the cylinder. More investigation would have to be conducted as to why, but it appears to be mechanical damage due to overheating.
    I'm going with No.
  10. MowerMedic77

    MowerMedic77 LawnSite Bronze Member
    Messages: 1,164

    I really hope you are kidding :hammerhead:

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