My poor little piston (What caused this?)

Discussion in 'Chainsaws and Power Equipment' started by Allen Lee, Dec 8, 2015.

  1. Allen Lee

    Allen Lee

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    Hey guys as I posted in another thread, I recently purchased my first chain saw and learned a big lesson. . (Don't buy a used chainsaw off Craigslist unless you know what your looking at. .) I bought a stihl 029 super that I found out after that it's motor is blown. Well I am taking it apart to put a new motor in it (49mm) and I got a glimpse of the piston and I wanted to see if you guys could offer me insight on what could cause this damage? Because I don't want this to happen to me, I want to learn. uploadfromtaptalk1449551223752.jpg Thanks guys! uploadfromtaptalk1449551170524.jpg
     
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  2. MasterMech

    MasterMech The Mechanical Moderator

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    Debris ingestion. It swallowed something it wasn't supposed to.
     
  3. Horkn

    Horkn

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    Yeah, that isn't pretty.

    Fix it up, and only let it ingest good stuff:)
     
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  4. Allen Lee

    Allen Lee

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    Thanks! How did it get something nasty in it you think?
     
  5. Guido Salvage

    Guido Salvage

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    Does it have an air filter? Is there a lot of carbon buildup around the exhaust port?
     
  6. cnice_37

    cnice_37

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    Is the locating pin in there on that second ring?
     
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  7. Barcroftb

    Barcroftb

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    X 2 on the locating pin.
     
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  8. Mastermind

    Mastermind

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    I'd like to see some pics of the outside of that jug. Looks aftermarket.

    You also need to take the bottom pan out of it. First you remove the rear bar stud.......

    Then clean every part throughly.
     
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  9. Allen Lee

    Allen Lee

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    Ahh now that I look at ot, the locating pin does appear to be missing on #2 ring. Could this have caused damage? It has an air filter, I will post more pics of the outside tonight.
     
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  10. redneckdan

    redneckdan

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    My money is on locator pin based on the skirt and port damage.

    Sadly, I've been there too. I've gotten screwed on every major purchase on craigslist in this area. Dunno what it is about this area, but people don't take care of their stuff. I grew up in an area where money was tight for everybody, people took care of stuff.
     
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  11. Allen Lee

    Allen Lee

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    Ya, it's amazing how people sell janky stuff too. So it sounds like the locater pin came out?
     
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  12. Cut4fun

    Cut4fun

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    Wow o_O my 1st used saw purchase was a burn too off FEEbay. Look what that lead too. :thumbs:

    Enjoy the ride and learning.
     
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  13. cnice_37

    cnice_37

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    It could be there, the pic makes it hard to see.

    If it comes out in the saw... well yeah that's a problem. If it isn't there to start with then those ring ends move, get caught on the intake, yep could certainly hurt too. Just a guess from a picture.
     
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  14. Allen Lee

    Allen Lee

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    Ahh I see. Thanks for the input, I will take a close look after work, and post some more pictures.
     
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  15. MasterMech

    MasterMech The Mechanical Moderator

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    I'm looking at the piston photo and it looks like the pin may have loosened and left a tell tale gouge just underneath and to the left?
     
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  16. Allen Lee

    Allen Lee

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    I see that too, the mark is almost going right to where all the damage is.
     
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  17. Allen Lee

    Allen Lee

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    Here's a few more picture, with a closer look I saw that the locator pins are both there for both rings, the rings were just turned so you couldn't see it. But I did notice a piece of metal in the bottom of the crank case so I pulled it out ( picture below) so I was looking to where it could go and it appears that It could be the clip that holds in the piston wrist pin on one side (also pictured below) what do you all think?

    Thanks, Allen

    [​IMG][​IMG][​IMG][​IMG][​IMG][​IMG]
     
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  18. Allen Lee

    Allen Lee

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    These photos didn't post

    [​IMG][​IMG]
     
  19. cnice_37

    cnice_37

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    Oh man, the old aftermarket wrist pin killer! Sure could be it, and you wouldn't be the first. Who makes the piston/ cylinder?

    I'd be digging deep into that crank before putting anything new back on that saw.
     
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  20. Allen Lee

    Allen Lee

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    Not sure. There doesn't seem to be any names on the cylinder/ piston. I have a whole new motor for it, crank and all
     
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