Has anyone have a brand new OEM stihl piston explode within seconds of the first start?

[GSully23]

Piston doesnt look new???? Heres a few pics. No I did not check the squish.

Absolutely brand spanking new

 

[lone wolf]

As others have stated, I'm going with the.......something metal hit something else that was metal.

Pistons just don't explode all by themselves.

Especially in a super short amount of time.

 

[lone wolf]

Piston doesnt look new???? Heres a few pics. No I did not check the squish.

Absolutely brand spanking new

Base gasket delete by chance, and you did not tell me if you used a piston stop yet?

 

[TBS]

Its happened before. Sometimes those piston ring pins come out, a piece of casting slag in the transfer, or bearing on the lower connecting rod lost a needle bearing.

 

[Chainsaw Jim]

It really seems like a broken ring could have caused that. I don't see the type of damage to indicate a circlip being left in the case. Pull the muffler in half to see if you find anything.

There is a regular style oem alternative for those brittle composite oil seals. That part number is 9640 003 1190

 

[hseII]

Wow....really surprised you guys are taking it this far out of context. I still have a set of the OEM seals sitting here, but I chose not to use them. No, I did not eat a bearing, they are all brand new. I was simply asking if this has ever happened to someone. The only thing I can think of is an issue with the cylinder walls, I did not inspect them that closely because it was new. I will include a picture of where the contact was made. I am a certified Yamaha outboard technician, which has nothing do do with chainsaws but I have been working on engines for almost 18+ years. Unlike many people I am a die hard stihl fan. You all have twisted this "question" in a very different direction. I was legitimately asking a serious question.....what do you think would have caused this?

I've never seen any of you all jump at someone's throat so quick.....but damn, so.something happened and I myself cant tell

No one is Jumping: Settle down Francis.

That Lone Wolf guy has been around a MS200 or 120.

You came here looking for help: you’ll get it if you set your ego down.

Did you use a piston stop at all?

If not, how did you get it apart & back together?

Why didn’t you inspect the cylinder again? Is it OEM? Just to confirm.

Was the arrow orientated correctly?

Why did you tear into it originally?


Sent from my iPhone using Tapatalk Pro

 

[Little Al]

As others have stated, I'm going with the.......something metal hit something else that was metal.

Pistons just don't explode all by themselves.

I don't know if it could be classed as exploding but some years back a neighbor brought a Stihl 034 still under warranty some half dozen tanks through it & he said it had locked up,took to dealer piston had broken through wrist pin webs leaving skirt still attached to rod & crown floating loose in the cyl telephone call some 10 days later all OK collect No Charge getting it home found to be a replacement new saw could never get a cause & effect report

 

[user 122190]

There is nothing (but a few fanatics here) that says OEM is bullet proof. Mechanic mistake, bad luck, bad part, really really bad luck, who can say?

 

[pioneerguy600]

Out of several hundred saws I have built I lost one OEM piston on its first cut. On a fully rebuilt and ported 394 the whole top of the piston broke off right through the pin boss web leaving one half of the web still connected to the pin, the rest stuck at the top of the cylinder bore. This was due to a stress crack, not from hitting anything. Luckily for me the saw stopped itself immediately and did no further damage. Just inspected everything and replaced the piston, saw is still running 5 years later.

 

[GSully23]

I did not use a piston stop from stihl, but I did use a piece of rope and lightly moved the piston until it was as close to TDC as it could go to remove my parts. The original reason for tear down was a broken flywheel side case in the oil resivoir, right near where they meet but the clutch side was fine. Also the saw would only run with full choke, so since I had to swap cases I might as well do the whole thing right?Regardless I did buy a whole set of spare OEM cases and crank ( which I was a little disappointed because it ended up being 020t cases).

And yes, I came here for help, and in all reality that's all you guys do for me, I might wrench for a living but you guys go above and beyond and I know lone wolf is the ms200t expert. I might not have many post but I've been reading his for years.

I did find one mistake on my part during tear down and my coil/magneto tolerance was tight, I dont believe tight enough to cause this but it was at about .10 mm instead of .25mm.

I have also found the metaor piston looked just as good by eye but the locating pins in the meteor are very easy to misalighn compared to the stihl. I wasnt trying to turn away any comments "due to an inflated ego" , but some people were poking fun at the matter. No worries, I have it all put back together and tommarow I'll see what happens and let you guys know.

 

[lone wolf]

I did not use a piston stop from stihl, but I did use a piece of rope and lightly moved the piston until it was as close to TDC as it could go to remove my parts. The original reason for tear down was a broken flywheel side case in the oil resivoir, right near where they meet but the clutch side was fine. Also the saw would only run with full choke, so since I had to swap cases I might as well do the whole thing right?Regardless I did buy a whole set of spare OEM cases and crank ( which I was a little disappointed because it ended up being 020t cases).

And yes, I came here for help, and in all reality that's all you guys do for me, I might wrench for a living but you guys go above and beyond and I know lone wolf is the ms200t expert. I might not have many post but I've been reading his for years.

I did find one mistake on my part during tear down and my coil/magneto tolerance was tight, I dont believe tight enough to cause this but it was at about .10 mm instead of .25mm.

I have also found the metaor piston looked just as good by eye but the locating pins in the meteor are very easy to misalighn compared to the stihl. I wasnt trying to turn away any comments "due to an inflated ego" , but some people were poking fun at the matter. No worries, I have it all put back together and tommarow I'll see what happens and let you guys know.

You can use a 3/8 impact gun instead of that rope in the cylinder, I wonder if the rope snagged a ring? Did you use a ring compressor for assembly? Which seals did you use? Did you vac- pressure test it? I'm thinking it will run good this time.

 

[GSully23]

Yes, every part was OEM. I used soap and warm water to clean the cylinder by hand but didnt feel anything out of normal.....I probly should have inspected it closer. I used rope as piston stop but did everything by hand, not impact.

 

[GSully23]

You can use a 3/8 impact gun instead of that rope in the cylinder, I wonder if the rope snagged a ring? Did you use a ring compressor for assembly? Which seals did you use? Did you vac- pressure test it? I'm thinking it will run good this time.

Thank you for replying, alot of the stuff I've learned about the 020 and 200t has been from you. The rope I used was tight and secured, had burnt ends to make sure it didnt fray. I wish I took pictures of the cylinder right after the incident but a slight piece of rope wouldnt ha e done the same harsh/sharp damage. There was nothing foreign found I side the casing, especially the type that would cause the stuff I saw. I honestly dont believe a piece a rope could have done that. I can take a picture and literally put the piston and rings together piece by piece.

 

[lone wolf]

Thank you for replying, alot of the stuff I've learned about the 020 and 200t has been from you. The rope I used was tight and secured, had burnt ends to make sure it didnt fray. I wish I took pictures of the cylinder right after the incident but a slight piece of rope wouldnt ha e done the same harsh/sharp damage. There was nothing foreign found I side the casing, especially the type that would cause the stuff I saw. I honestly dont believe a piece a rope could have done that. I can take a picture and literally put the piston and rings together piece by piece.

I was thinking maybe the rope snagged a ring when in the cyl but
In order for the rope to break a ring you would have felt resistance taking it back out of the cylinder if it was jammed .

 

[GSully23]

I agree....and the cylinder/piston was tested a multitude of times. Also, it would take much more than a frail piece of rope to cause damage that shows such significant/harsh marks???? Or am I wrong . The most frustrating piece of evidence is that I can piece the fractured piston and rings completely together without any significant signs of impact

 

[TBS]

Did you find anything in the muffler? Just out of curiosity did you remove both wrist pin clips?

 

[GSully23]

Did you find anything in the muffler? Just out of curiosity did you remove both wrist pin clips?

I found nothing in the muffler, and yes both wrist pin clips were intact. I'm still at a loss, like I said I'm a die hard stihl fan, and the meteor just goes to show why... but I just dont understand what happened here.

 

[lone wolf]

I found nothing in the muffler, and yes both wrist pin clips were intact. I'm still at a loss, like I said I'm a die hard stihl fan, and the meteor just goes to show why... but I just dont understand what happened here.

I'm saying the rope could have snagged a ring fractured it and it flew apart when running and snagged a port. Some foreign object or trauma could have been involved,small chance the piston was fractured from the factory. Did you use a ring compressor? did you have any trouble putting the cyl on the piston an break a ring?

 

[huskihl]

I can piece the fractured piston and rings completely together without any significant signs of impact

Something came out after assembly like a chunk of bearing or bearing retainer or a chunk of wrist pin circlip, Or you broke a piece of the ring during assembly. Or something was hiding inside the crankcase, intake tract, muffler, etc.

Either way, the pics above are your initial points of impact.

 

[GSully23]

I'm saying the rope could have snagged a ring fractured it and it flew apart when running and snagged a port. Some foreign object or trauma could have been involved,small chance the piston was fractured from the factory. Did you use a ring compressor? did you have any trouble putting the cyl on the piston an break a ring?

I used the zip t method and had no issues...went on as smooth as butter and used my fingernails to set them in place