Read my piston if you can

[Glenn RH]

These pics are of a stihl ms310 piston. The rings are seized on the exhaust side, the rest of the piston looks fine as does the jug . Can I get away with just replacing the rings (I havent tried to remove the old ones yet)

View attachment 48806

View attachment 48807

View attachment 48808​

in picture of piston top ,exhaust side is on top of picture

 

[hokiebob1]

Looks to me like you at least need a piston and ring--not sure about the cylinder. Bummer, what happened?

 

[GASoline71]

No... that piston is shot... the scratches and scoring on the piston and skirt are pretty bad. Replace it and you will thank me later.

Gary

 

[ropensaddle]

Gasol is right about that that piston is junk. Raw gas maybe?

 

[Goat]

I'd replace that slug and rings are a given...

Can you post pictures of you cylinder?

 

[ropensaddle]

cylinder toast also with that much scoring

 

[Glenn RH]

picture of cylinder

Ill try to get a pic of the jug later tonight , right now I gotta run, Red Sox on.

 

[Stihl #1]

Hey Glenn,
It is possible to group chain saw piston failures into some "typical" descriptions regarding reading the failures. There is always the odd saw that doesn't fit the typical failure, and some saws may have multiple faults that may cause a-typical damage. Having said that, I feel you have a typical lean running failure, which in my experience is the most common cause of damage in a chain saw. Be sure to check for any faults present before running it. It is best to do a vac/pressure test before teardown to see if the engine pan or seals were leaking. Was the H screw in too far? Impulse hose in place or leaking. Fuel filter restricted or a hole in the fuel line, tank vent working properly? I always do a full analysis of the unit before teardown to locate any and all faults present, and then those faults should confirm why the engine failed and match the damage.
Typical lean damage is scored exhaust side with little or no damage on the intake side, blue wrist pin and needles, and there may be some scuffing on the bottom of the intake side due to high RPM piston slap.
Typical unmixed fuel is damage on both sides of the piston, do a blotter test to check the fuel in the carb for oil. When you check the engine before teardown, you probably will not find any lean faults, which helps to confirm that it was lack of lubrication.
Overhear failures will usually show 3 or 4 corner scoring on the piston, and some melted plastic around the cylinder, and again, no other faults will be present.
Check the threads last week or two about using acid and fine emery to save the cylinder, and you may be able to just replace the piston.
HTH

 

[THALL10326]

read this one too

Worth saving? I don't think so.............

 

[MikeInParadise]

Worth saving? I don't think so.............

Aw...Nothing a little JB weld wouldn't fix :biggrinbounce2:

 

[GASoline71]

Worth saving? I don't think so.............

Hmmm... I don't know, maybe use some JB Weld...:hmm3grin2orange:

Gary

 

[GASoline71]

JINX!!! :biggrinbounce2: :hmm3grin2orange:

Gary

 

[MikeInParadise]

Just goes to show that great minds think alike!

 

[THALL10326]

Not to derail his thread or anything but thats the first piston I've ever seen burn clean through. Pre-ignition or as some call it, dieseling, from a hot spot on top of the inside of the cylinder was the culprit. She sure got hot about it didn't she....

 

[THALL10326]

These pics are of a stihl ms310 piston. The rings are seized on the exhaust side, the rest of the piston looks fine as does the jug . Can I get away with just replacing the rings (I havent tried to remove the old ones yet)

View attachment 48806

View attachment 48807

View attachment 48808​

in picture of piston top ,exhaust side is on top of picture

Piston is cooked for sure, no saving that one. Has to be some melt down in that cylinder as well from that piston.

 

[Dan Forsh]

Just goes to show that great minds think alike!

"..and fools never differ":hmm3grin2orange:

 

[MikeInParadise]

"..and fools never differ":hmm3grin2orange:

Hey SWMBO is on her way to the UK this weekend, I will have to send her over to straighten you out! :deadhorse: :hmm3grin2orange:

 

[RiverRat2]

Come on Thall

Worth saving? I don't think so.............

Is this a set up???? You got me gun shy you slick devil,,,,,,

 

[Dan Forsh]

Hey SWMBO is on her way to the UK this weekend, I will have to send her over to straighten you out! :deadhorse: :hmm3grin2orange:

SWMBO?

Should I be aroused or scared?

 

[stihl 440]

shot

Piston is cooked for sure, no saving that one. Has to be some melt down in that cylinder as well from that piston.

Yup! Iwould say that P&C is shot with that much scoring!