Piston diagnosis

[Adirondackstihl]

My guess was:
View attachment 33483

The guy said it only tan for a few minutes.
I showed it to parts manager and then it made its way around the dealership through parts and service.
I hadnt considered the piston stop because i use a plastic stop, but i can check the indentation on the stop as well

If you look close, you can see indentations of tool marks from a lathe pressed in there.
Definitely not a spark plug, but rather a metal piston stop.
That piston never saw compression. He knew he *f-worded up, the moment he *f-worded it up.
He used a big *f-worden wratchet to install the clutch........
That's how that went down

 

[jakethesnake]

I do think that makes sense why the hell use a metal piston stop? My method probably isn't the best but I use cotton string

I don't own a stop

 

[Gunn]

Looks like a metal piston stop did this. A plug doesn't have the radiused end like the piston shows.

If the spark plug did this wouldn't you see remnants of threads leaving their mark as well?

 

[Stump Shot]

Most likely scenario of guessing would be an impact wrench on a clutch that inadvertently spun the wrong way and free wheeled the piston up into the stop with some inertia behind it. Bang!

 

[Definitive Dave]

I was thinking the electrode on the tip of the plug, but piston stop also very possible.

 

[Milesrunningman]

Definitive Dave
When do you need to get back to the "customer"?

I have a wrecked Stihl TS400 that's about to be rebuilt. Quite happy to go into the garage over the next couple of days and see if I can recreate the damage with the metal piston stop tool?

The saw I am working on will need a full rebuild kit and the parts are trashed anyway.

 

[Simondo]

I was thinking the electrode on the tip of the plug, but piston stop also very possible.

That would mean that the wrong length plug was fitted.... Far less possible than the stop being at fault I feel .

 

[jacob j.]

I was thinking the electrode on the tip of the plug, but piston stop also very possible.

It's definitely from a metal piston stop. I saw many of those at the dealership. Defective customer...

 

[Chainsaw Jim]

All evidence points to using the wrong kind of metal piston stop. The machine marks, the angle, the lack of multiple strikes from a running motor, the cracks being made from slow steady pressure instead of a clean sharp break....

 

[RIDE-RED 350r]

No way in hell did that saw run, not even for a few minutes. Steel piston stop and too much force with some sort of tool, be it an impact or just turning the clutch the wrong way with a wrench, 100% guaranteed.

I have and use a steel piston stop, but NEVER use it in conjunction with any sort of impact wrench and am careful to slowly rotate the engine till the piston stops against the stop, and then only hand tools used. Haven't had an issue yet.

It's one thing to not know any better and make a mistake like this. Totally another thing to try and pass the cost of the learning experience off to the seller of the piston. Take your lumps, learn from your mistake, buy another piston from that good seller, and move on with your life. Be a man, not a child with a participation trophy!

 

[Redbull661]

Tell that you'll do him a big favor and give him MELT value as a refund!

 

[Nitehawk55]

Dropped by the seller prior to shipping

 

[Wagnerwerks]

My guess is the customer would say he used a stop, but the piston was defective and crunched under the load.

 

[RIDE-RED 350r]

Steel vs aluminum: Steel wins, every time.

A piston does take alot of force, but it is designed to take that force over the whole surface of the crown and channel it to the wrist pin.. It won't take a heavy load on a very small area like that. I'm sure that one could do that kind of damage with a piston stop even using a hand wrench.

 

[Tor R]

Metal piston stop, I use plastic piston stop and I sure gone continue with it.

 

[Mastermind]

Hi,
I'm new to this forum and impressed with the masses of information!

I cannot speak for chainsaws. But seen exactly the same damage on stihl concrete saws from using a piston stop tool and over cranking the clutch on removal. Could be a plug, but I would say piston stop tool.

Must have given it the beans mind. As I have yet to do that, to even aftermarket pistons!!!!

Welcome to OPE sir. Enjoy the place.

I was thinking the electrode on the tip of the plug, but piston stop also very possible.

He never would have been able to start it with a plug hitting like that. Two things. One it would have locked up tight, two, it would have closed the gap.....and no spark.

 

[Mastermind]

Metal piston stop, I use plastic piston stop and I sure gone continue with it.

I use a short piece of rope......

 

[Tor R]

I use a short piece of rope......

I dont like the rope, always feel I leave a few fibers left, doesnt mather I guess.
I always wanted metal piston stop but when I saw the marks they leave on pistons I thought no way!

 

[RI Chevy]

I say run some weld and fill in the cracks and send it back to him telling him the manufacturer fixed it. As good as new.

 

[Tor R]

customer returned via ebay
Customer believes manufacturer defect
Stihl ms192t

What say you?
View attachment 33470 View attachment 33471 View attachment 33472

I dont know if this help or not, with the torque he has used his flywheel and clutch aint gone come off easy