CK35 HST shattered piston at 400 hours

[chuck172]

Lets all keep up to date with this thread. If Chris doesn't get satisfaction from Kioti, how bout we go to the next step. As Kioti owners and prospective owners we get together and flood Kioti with emails and phone calls. Hopefully it won't come to this and Kioti will do the right thing. Lets wait and see.

 

[Fawken]

I'm all in, Chuck. To the Kioti owners who think I'm brand bashing, I don't play that game. I work really, really hard for what little I have and when I see a situation like this I immediately think, this could be me. Sometimes I sell a motorcycle that I have restored and I won't sell it to even a perfect stranger if I think it may have a mechanical issue. I've even gone back to repair cameras that were out of warranty when I couldn't immediately determine a cause for the failure.

 

[dfkrug]

You see a snap ring...

Well, now I am more puzzled, Chris. That sure looks like a wrist pin retainer. For
THAT to come out with the piston still in the cylinder, some serious destruction has
to happen. I want to see that piston.

 

[Fawken]

Well, now I am more puzzled, Chris. That sure looks like a wrist pin retainer. For
THAT to come out with the piston still in the cylinder, some serious destruction has
to happen. I want to see that piston.

Yes, I was curious about that as well- however when the skirt shattered and the bottom ring came out I can imagine all sorts of oscillation going on when the tractor continued running. The more telling part of the pictures for me is the close-ups of the skirt fragments. Some of them have carbon build-up on the broken facings and others are clean and shiny indicating that the skirt was cracked long before total failure.

 

[paulfun9]

Yes, I was curious about that as well- however when the skirt shattered and the bottom ring came out I can imagine all sorts of oscillation going on when the tractor continued running. The more telling part of the pictures for me is the close-ups of the skirt fragments. Some of them have carbon build-up on the broken facings and others are clean and shiny indicating that the skirt was cracked long before total failure.

Are you sure its not just the picture. I see lots of shadows but then again I did not spend much time looking at the pics. I have made it a point to never try to make statements on why or how an engine failed unless I have the parts right in front of me for inspection. Too many things that can effect the picture without having the camera and light moving around the part in sync.

 

[Fawken]

It's pretty clear, Paul. Look at the picture on page five with the fragments on a paper towel. The large fragment at the top right shows 3 different levels of carbon deposit. The shiny area is where it finally gave way and came apart. Just above that is a medium area as the crack progressed. Then to right is a large dark area that was exposed to crank case vapors for a long time. It is possible to measure the amount a carbon deposited in that crack, compare it to the deposits in the the non contact area of the bore, and get a good estimation of when cracks first developed in that piston. Since it doesn't collide with anything in the crankcase with anywhere near the force required to shatter, it likely was installed with hairline fracture when assembled. He should get a new motor.

 

[Coyote machine]

Here's what I'd like to know: What was your neighbor using your tractor for and for how many hours/days did he have it?

That snap ring is not a circle, (but who knows why or how it got the way it is). If it failed, or was installed as it looks now, it could be the 'key' to the puzzle. Time will tell.

 

[Fawken]

Here's what I'd like to know: What was your neighbor using your tractor for and for how many hours/days did he have it?

That snap ring is not a circle, (but who knows why or how it got the way it is). If it failed, or was installed as it looks now, it could be the 'key' to the puzzle. Time will tell.

A motor will run just fine without a wrist pin retainer, but eventually the wrist pin will migrate to the cylinder wall and over time wear a groove in the bore to where you will notice a significant amount of bluish smoke in the emission. That retainer popped out when the skirt finally gave way as the bottom part of the groove is located in the shattered portion of the skirt. A lot more is clear with the additional pictures he posted. Some small fragments appear to have been floating in and around the crankshaft long enough to show buffing and grinding at work. A tough rebuild for sure.

 

[holeycow]

Yup. He should get a new motor. It should be on the boat already.

 

[Coyote machine]

I'm well aware of how engines work; especially after having owned and run a foreign auto repair shop for over ten years. We rebuilt all kinds of engines, including Mercedes Benz diesels, as well as Volvos, Saabs, and all kind of eccentric, and unusual autos from all over the world; Lambos, Maseratis, Jags, Talbots, Rolls Royce, to name a few.

The additional pics, (I did not look at them beyond noting they were available to look at), may indicate serious to severe damage from the piston debris getting 'hammered' by the still running engine; yet another reason to NOT restart the engine again.