Chain Saw ate plug

[chopped]

:confused2:I just wanted t o make a post to see if anyone has ever had or heard of this happening.
I have a johnsered chainsaw, and its about 5 years old. Never had the plug out of it until today.
I was cutting thought three tanks of fuel when I heard a tinny noise much like a loose piece of tin. I shut the saw right down, and it wouldnt start again. I then removed the cover and when I touched the plug it was already loose with some black smoke marks around it. I thought OK loose plug NP.
I then removed it to find that the small metal that is bent over to the inner electrode was gone:licking:
The engine would crank over fine and I made sure that that metal part wasn't int he cylinder I put in a new plug and it runs so far..
its it possible that it broke off? burned up? and got passed through the exhaust valve?
Or possibly slow wore down to nothing?
Either was I assume it was just vibrations and expansion that made it loose to begin with.Maybe I should a checked it for tight before.

 

[RalphVa]

Wow. Sounds like a bum spark plug. Was it the original?

Lots of use out of the chain saw this year. Am using mostly my 38 year old Stihl 009L. These were still on sale up until about 3 or 4 years ago, at a slightly less price than I paid for mine in 1972. It's harder to start cold (unless I squirt some starting fluid into it) than the newer Craftsman with the little pump thing, etc., but it STARTS immediately once warm and shut down. The Craftsman often won't restart once hot. Not something you want to take into the woods a mile or so from the house.

Ralph

 

[RoyJackson]

Hard to say without seeing a picture of the plug.
It could have eroded away, but I'd think you would have had hard staring before it eroded too far (gap would be too long).
Did you replace the plug and start the chainsaw?
BTW, spark plugs should be torqued when installed. It's a good idea to use an anti-seize paste too, especially if the head is aluminum or magnesium.

 

[FxdGrMind]

It's a 2 stroke, no "Valve", rather an opening in the cylinder wall... thats the good part. Glad to hear you looked in to see if there were any metal bits floating around.
Did the wall look scored at all? and did the new plug thread in easy and torque down ok?

From just reading it could have been corrosion or "hot running" and burned through it... I'm thinking the sound you heard though was "detonation" and that in and of it's self may have done the deed to your plug. It would have shut down quite fast after that unless there were "Hot Spots" to light off the mix in the cylinder.

Take the plug out and double check the piston head for damage though. Hopefully no damage and no scoring on the walls.

Fingers crossed.

 

[Dead Horse]

High content ethanol in gasoline is causing detonation in a lot of 2 cycle motors. I use Startron in my chain saw and sled fuel for this very reason, the cars that require high octane get a dose of it at fill up too.

Use high octane fuel in your saw, specially good ones like a jonsered, husky or sthil..... Bad fuel is all over......... and the gd gubmit could give a rat's patoie about it.

Guys are burning up 2 cycle motors with the crap stuff sold at the pumps......... don't believe it..........??????

Check out Skidoo's experience with their HO 800 cc motors!!!!!!!!!!!!

 

[RobertN]

I'd pull the muffler and check the piston, make sure it is not scored. Sounds like it might have got hot.

I would also double check your fuel. Is it fresh, and mixed to proper ratio with a good quality oil? Make sure you did not accidentely grab the straight gas; that is the death of a saw.

I only use premium gas, with premium Stihl or Husky oil, mixed per the bottle of oil. The other thing, I only mix a gallon of gas at a time, so I keep fresh stuff cycling thru. One other thing, I have my 2-stroke mix in a clearly marked can so it does not get confused with straight gas. Same with diesel for the tractor; it is in it's own yellow fuel can.

Ask my Husky 1100CD; it is from the early 70's and still runs like a champ!

 

[3BPercherons]

Lots of use out of the chain saw this year. Am using mostly my 38 year old Stihl 009L.

I have a Beard-Poulan 306A that's at least that old. Rebuilt the carburetor and replaced the fuel lines/filter over the winter and it runs like a champ.

 

[Soundguy]

anyone here ever add a lil diesel to their fuel mix to help with pre-det?

soundguy

 

[Dmace]

Most likely the ground electrode broke off and quickly made it's way out the exhaust passage. It's probably still in the muffler, take it off and shake it and you might hear it in there.

Like others have mentioned, this useless Ethanol enriched fuel is causing more problems then it "supposedly" fixes so I use an Ethanol treatment in all my 2-cycle motors to help with this and the tendency of this crap fuel to grow algae very quickly when stored. They tend to run pretty lean with this fuel which means they are running hotter and that would cause the ground electrode to weaken and break off under load. I also run one heat range colder plug in my 2-cycle motors to offset the hotter engine temps. For example if your plug is an NGK BP6ES then use a NGK BP7ES for a colder plug.

 

[chopped]

Good tips
this post has got me wondering. Maybe I should mix some new fuel myself..And see what others say about the diesel in it also..Is the idea the diesel would do the same as the stabil?

 

[chopped]

Yes it was the original and the electrode is gone , but you can see the small 'nub' where it was attached.I was a cold day when I was cutting, and I was cutting allot i was ON my third tankful pretty much straight out. I cut the wood to just under 12 inches so on a good size log its running quite steady.I can even notice that the oiler even set on full sometimes has a hard time keeping up.So isn't possible it was running hot and steady..
Question if it was running hot is this why the plug was loose? Never been a problem in all these years.
It had a new Champion plug now and was running OK. so time will tell I guess.Maybe it was a bum plug.. ??
Also I tested the plug with it outside the engine and it actually got a good spark even without the electrode. ..Even after the noise it still was running I manually shut it down. but then wouldnt restart.Possibly it was so hot it "dieseled" ??

 

[Dmace]

Good tips
this post has got me wondering. Maybe I should mix some new fuel myself..And see what others say about the diesel in it also..Is the idea the diesel would do the same as the stabil?

Adding a little diesel to gasoline for a 2-stroke mix is just the same as running a richer (more oil) mixture. It will help slightly with pre-detonation because of the added oil but will do NOTHING to offset the downfalls of Ethanol fuel like algae growth, deteriorating fuel lines, lean mixture, hotter engine temps, etc...

When the engine overheats or runs close to overheating, the head actually expands slightly and the threads for the plug can even expand slightly due to the difference in metal types. Between this and the vibration, the plug could easily back itself out some. Also, the plug will still spark outside the motor since it can ground to the threads of the spark plug itself but it will not spark under the high compression in a cylinder since it has to "arc" too far and the spark actually gets "blown out" by the high compression. It was still running due mostly to the momentum of the engine already spinning and you weren't still accelerating the engine.

 

[arrow]

This is exactly what happened. You are either running your saw too lean or your gas mix is old. I was standing next to a guy one day whose plug flew out of an almost 7 hp chainsaw and hit me right in the hard hat and almost knocked the helmet off. He had leaned out his chainsaw for speed enough to cause detonation and it came out like a cannon shot. Don't forget, it had to break loose from the wire after stripping out of its threads and still had quite abit of force. I never saw that happen again but I saw plenty of what happened to you. I never adjusted any of my saws to their screaming point. Just so they're 4 stroking is plenty if you are looking for saw longevity over production speed.

 

[easygo]

I also only mix up 1gal of fuel at the time. I buy the highest grade gas and add quality oil and some fuel stabilizing additive. You can find ethanol free stabilizers nowadays. I have done that since the saw was new about 5-6 years ago and no problems. Use the same stuff in all 2 stroke engines and no problems stating or running them even after several months of sitting.

Edit: I do add the stabilizer stuff to all small engines I have and have had no problems.