Stump The Technician...Name That Failure,,,

Discussion in 'Mechanic and Repair' started by piston slapper, Dec 3, 2012.

  1. 04cubcadet3235

    04cubcadet3235 LawnSite Member
    Messages: 61

    what i can see that probably happened here is at the factory they forgot to put the snap ring in on the one side, and the side with the snap ring dug into the cylinder because if the other side had the snap ring, it cant go inwards so it got pushed out and started destroying the cylinder wall
  2. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    Id be lying to you..... if I told you that diagnosing that engine didn't push the limits of my technical least until I disassembled it...
    The clue here is that there wasn't any knocks or noises most of the time...just intermittently..
    At first glance I figured ...just like you guys..that the wristpin slid out and pivoted..causing the break in pin boss opposite the gouge in the cylinder..
    If that had been the would have broken both pin bosses , or at least damaged the other one bad enough to give the piston a consistant knock or rattle..

    Failure Analysis is only as good as your experience or reference materials..
    The two I have presented so far in this thread....are not in anything I have read...
    The more I know...the more I know that I don't know....
  3. 04cubcadet3235

    04cubcadet3235 LawnSite Member
    Messages: 61

    was there any metal shavings anywhere of anykind when you ripped down that engine?
  4. kymowboy

    kymowboy LawnSite Member
    Messages: 69

    What kind of engine was it that had the piston pin failure?
  5. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    Cubby...of course there was a metallic sheen in the oil...but no pieces.other than the 2 pieces that broke off the piston.. was a Kohler CV750 30 hp engine...

    I realize you new guys aren't familiar with my certifications..I don't flaunt them much..
    Id rather show you that I have been a certified Kohler Expert Technician for almost 15 years.....
    Than to talk about that wall covered with shingles.... signature will warranty a shortblock....and did on the engine in the pic..
  6. 04cubcadet3235

    04cubcadet3235 LawnSite Member
    Messages: 61

    did that engine with the air cleaner plate filled with dirt still run? ive never seen any air cleaner plate so dirty how did the carb look when you took that apart? ive seen air filters turned black with dirt and leaves but not the inside plate that dirty. good thing when ever i take off an air cleaner i put the bolts back. The worst ive seen of a carb was when i split the one on a 25hp horizontal that was having trouble running had about 2mm of dirt on the bottom. Turned out thats wasn't the problem. The problem was the left side spark plug was completely filled with carbon, there was no gap, and it was using excessive oil. The real problem here was a bad oil control reed valve.
  7. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    Yes...the engine was still running....but not real good....
    All that dirt happened in 2 you can see that the air filter is brand new..
    It was a fleet mower that gets serviced by the guy running it....he doesn't work there anymore..
    I guess he either lost or forgot the wingnut....luckily I didn't find it inside the engine during the teardown.
    The dirt wiped out the rings and the crosshatches...and a nice chunk of the owners money..

    On every rebuild I do a 100 percent inspection of EVERY component...yes the carb was clogged..
    Once I build an engine...its my anytime it acts up I get the phone call....
    A few years ago I had a guy chew me out because he ONLY GOT 10 YEARS OUT OF MY REBUILD...
    They are out there.....True Story...
  8. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,188

    For my money, KY (we wont even go there) Mowboy got it!
    And Wayne55 was a close second.

    I can guarantee the first thing you thunked when you peeked them BBQ smoke teared up eyes into that cylinder was, " damn, another pin clip went south"...........'fess up!!!!
  9. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    Cmon're reading right past the good parts....
    They say a picture paints a thousand words. Not sure what you're reading into the picture.
    When your the one signing off on the warranty your opinions must be based on FACTS..
    All you guys were Stumped....just in time....needed to throw another Stump in the BBQ..:waving:
  10. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    The purpose of this thread is to Stump all you smart people...make you use that space between your ears..
    If you wanted a mamby pamby thread showing fouled ain't here...
    The better you understand what can and does happen inside an engine...
    The easier it will be to diagnose an engine from the outside...

    BTW...That stump was just right...smoker holding 225...sunny day in the low 80's..

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