Junk oil.
Use good oil
Use good oil
How the hell did I kill another Stihl?
- Thread starter Skunkdynamite
- Start date
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drf255
BAD CAD
Did you check the piston when you received the saw? Believe it or not, compression can come up normal even in scored saws. I’ve been burned before and choose visual inspection of the piston as a better indicator of condition.
Not trying to be insulting, but do you know how to tune a saw by ear? Would be helpful to know if you had it tuned correctly or whether it was leaned out. Did you check the tach?
The good news is that pistons are cheap, even OEM. Your jug may clean up, but you’ll need to figure out what your original issue is or you’ll be back in the same boat in no time.
Not trying to be insulting, but do you know how to tune a saw by ear? Would be helpful to know if you had it tuned correctly or whether it was leaned out. Did you check the tach?
The good news is that pistons are cheap, even OEM. Your jug may clean up, but you’ll need to figure out what your original issue is or you’ll be back in the same boat in no time.
Skunkdynamite
ArboristSite Lurker
Thanks for the insight!My gut says the guy before you ran some old stale fuel and possibly too much oil in the mix for a good long while. I'd check that clean spot for a leak from possibly a loose cylinder bolt too.
View attachment 799507
Which would explain the lean condition heat scoring and glazed ring.
I'm guessing who ever you bought that from knew something was awry, and pled ignorance. That gooey syrup fuel probably made the rings give a normal compression reading until it warmed up and got dry from heat, then it lost compression from glazed over rings.
Not to get into a fuel debate, but unless you buy from a really busy gas station, chances are their non-ethanol fuel is already starting to get stale when you buy it. Or likely doesn't have the mid-grade octane that Stihl recommends.
Really fresh premium fuel from a busy gas station, with the max 5% ethanol in it (by law), is far better for your saw's longevity.
Edit;
Isn't it odd that there are only fines, and no larger wood chips mixed in, where it's stuck to the engine?
I do have a good mechanical background, but I have very little experience with 2 strokes. I have the expectation that a commercial saw or even a homeowner saw should supply me with firewood until I'm old enough for a pellet stove
The fine dust is indicative of being run with a dull chain? It had a new Bar and chain on it.... And fine dust in the nooks and crannies. Looking at the sellers ratings, they've gone downhill in the last 6 months to a year. Not completely ducking responsibility here, it I barely ran this saw.
Should I get a Meteor P&C kit for it? Seems like there's no complaints about them, I really don't trust Chinese crap. I need this to last... I just cleared my workbench!
This was supposed to be my intermediate saw, for felling and light work. I have the 390 for bucking the log truck loads and the 170 for the light work.
shadco
ArboristSite Operative
In about 30 minutes at the most remove the cylinder....clean it up, put a new $30 meteor piston in, pressure/vacuum test and run it another 1000 hours....from the looks of the piston the cylinder will need very little work to get ready. I would not blame the seller as new ones shyt happens......
Looks like carbon scoring to me.
Clean it up, vac/pres test, pull jug and clean scoring/carbon, new piston, assemble 2nd vac/pres test, fix any leaks.
Clean it up, vac/pres test, pull jug and clean scoring/carbon, new piston, assemble 2nd vac/pres test, fix any leaks.
Skunkdynamite
ArboristSite Lurker
30 minutes! So I made the right choice on a pro saw
rebuild it,,and sent the old man the bill. tell him if he don't pay it, I see you in small claims court..DA old man...
My gut says the guy before you ran some old stale fuel and possibly too much oil in the mix for a good long while. I'd check that clean spot for a leak from possibly a loose cylinder bolt too.
View attachment 799507
Which would explain the lean condition heat scoring and glazed ring.
I'm guessing who ever you bought that from knew something was awry, and pled ignorance. That gooey syrup fuel probably made the rings give a normal compression reading until it warmed up and got dry from heat, then it lost compression from glazed over rings.
Not to get into a fuel debate, but unless you buy from a really busy gas station, chances are their non-ethanol fuel is already starting to get stale when you buy it. Or likely doesn't have the mid-grade octane that Stihl recommends.
Really fresh premium fuel from a busy gas station, with the max 5% ethanol in it (by law), is far better for your saw's longevity.
Edit;
Isn't it odd that there are only fines, and no larger wood chips mixed in, where it's stuck to the engine?
I use non ethonal high test in all my equipment and carbed cars. But isn't the federal law 10% max?
Dph1256
ArboristSite Operative
I believe that there is a 5% minimum in gas. They use ethanol as an oxygenate. It used to be lead but that was bad then they used mtbe but that caused cancer.
I love those saws. Just throwed a meteor piston in 2 and right out of the hatch was already doing 155+ on the compression test and will improve from that.
HiDid you do a pressure and vacuum test when you got it?
I now see this as essential when getting a used saw with some time on it. WHY?
I never know if it got run with E-10. E-10 mix can harden the rubber crank seals. Hard seals can leak and I have gotten burned up saws (not that old) with leaky seals. Sure they will run, sure they seem to make reasonable compression. Then when used in a long heavy cut the leaking seal.... vacuum leak and poof melted piston.....
Any aged saw I get or work on for my friends now gets a vacuum/pressure check before I will use it to pull a load. Sure you can squirt some mix in the carb for an ignition test, but I'd never do a cut before a V/C test.
Just my 2 cents
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It is not essential! Run the saw will tell you most of what you need to know. Doing a pressure/vacuum test is not a simple thing, and is as different as it is difficult from saw to saw. A while back checking the metering set level was all the rage. Most don't even know what a metering set level was or is, but it became essential in diagnosing all chainsaw problems. Lots and lots of wannabe professional chainsaw mechanics on this forum. Wannabe is the emphasis, who really just repeat what they hear or read, with little understanding of what they are mis-propagating.
Compression reading pictures on-line on a used saw is in the category of puffing. Might even be the compression from a air compressor tank instead of the saw.
Buying a used saw on-line from flea bay is also in the category of buying a pig in a poke, especially if no return time stated.
I've seen saws with good compression reading but when the muffler was removed for a visual it would be sadness.
With that much carbon I would check the spark arrestor and if no arestor found would be ???. (someone throwed it away previously due to being clogged)
I also make sure that the muffler is bolted down tight and the gasket is in place. Fine dust can be sucked into the cylinder if muffler is loose or not gasket for a good seal.
In addition to using a tach when tuning a chainsaw I've started using a infrared thermometer to make sure that the saw is not overheating when it is into a full bar cut and loaded up heavy on a long cut. This confirms that the saw is not overheating due to leaning out, cooling fins clogged or other issues. I've seen saws that were tuned too lean but it would not be noticeable when taking short fast cuts and not loading up the engine for a long full bar cut. (sometimes the saw will start smelling like a hot engine, hot plastics when it starts overheating and may even seize (piston swelled into the cylinder) when in the cut or stalling and then re-start and run ok for awhile after it cools down)
I'm checking the temp at the piston/cylinder block area and the saw should not exceed 350F and may not get over 325F. If it does get too 350F it will just be a gradual temp rise. If you see the saw get to 350F fast and headed towards 400F it is headed for self destruct. (piston swelling, etc) Take the saw out of the cut and let it run at medium throttle to cool down before killing the engine. If close to 400F and you kill the engine it will get hotter.
The Infrared thermometer are not expensive now days and this block temp testing can be done without a helper if the chain is sharp using a test log on the ground. (the saw will load itself)
Buying a used saw on-line from flea bay is also in the category of buying a pig in a poke, especially if no return time stated.
I've seen saws with good compression reading but when the muffler was removed for a visual it would be sadness.
With that much carbon I would check the spark arrestor and if no arestor found would be ???. (someone throwed it away previously due to being clogged)
I also make sure that the muffler is bolted down tight and the gasket is in place. Fine dust can be sucked into the cylinder if muffler is loose or not gasket for a good seal.
In addition to using a tach when tuning a chainsaw I've started using a infrared thermometer to make sure that the saw is not overheating when it is into a full bar cut and loaded up heavy on a long cut. This confirms that the saw is not overheating due to leaning out, cooling fins clogged or other issues. I've seen saws that were tuned too lean but it would not be noticeable when taking short fast cuts and not loading up the engine for a long full bar cut. (sometimes the saw will start smelling like a hot engine, hot plastics when it starts overheating and may even seize (piston swelled into the cylinder) when in the cut or stalling and then re-start and run ok for awhile after it cools down)
I'm checking the temp at the piston/cylinder block area and the saw should not exceed 350F and may not get over 325F. If it does get too 350F it will just be a gradual temp rise. If you see the saw get to 350F fast and headed towards 400F it is headed for self destruct. (piston swelling, etc) Take the saw out of the cut and let it run at medium throttle to cool down before killing the engine. If close to 400F and you kill the engine it will get hotter.
The Infrared thermometer are not expensive now days and this block temp testing can be done without a helper if the chain is sharp using a test log on the ground. (the saw will load itself)
Skunkdynamite
ArboristSite Lurker
Wow Okie! That is pretty thorough! Good to know! I have to commit to the vac/pressure testing first. I have a standard Vacuum pump, but I have to get something together for pressure. I need to do some searching on this topic, it's pretty clear that if I invest the time in testing that I'll save time and money. Which is why I am working on my equipment to begin with... I've been getting workable results tuning everything by ear for years, but like I mentioned I'm definitely wet behind the ears with 2 strokes... I'm not a fast learner either 
Huskybill
Addicted to ArboristSite
Proper carb adjustment. Not too lean. When your cutting are you at wide open throttle? The carbon build up suggests your not running at wot. Only because I seen guys do this before when there new at cutting. I even had a buddy that did this. I taught him to run wot when cutting.
1hander
ArboristSite Operative
ive always tuned by ear but in the last year or two ive realized th..at i would never tune my LS3 418 stroker by ear, that would be stupid with all the time and money i have in it and it would explode.
thats why its equipped with wideband O2s, standalone ECU, dual knock sensors. and water injection. they are tools to keep it alive and healthy ..
so why would i not do that with my 2 strokes.....so not 3 days ago i ordered a tach to compliment the infrared therm i already have.. 2 strokes are highly wound little suckers , and with all the tech and cheap as it has gotten theres no excuse for me to not go a little further to make sure you have a healthy saw or saws, i always happy to learn something new or learn something from another person
the only parts i ever used on stihl saws other than stihl was meteor and never had problems with them personally
ive learned my lesson with chinese and knock off parts..
i learned it with bmw parts, nothing is as good as those OEM bmw parts, so now i just bear it and grin when its time
to buy parts for my old bimmers. its just not worth doing the job 3 to 4 times in 2 years as opposed to doing doing it once every 10 years.
if youve ever worked on a bmw, and i mean the blood and guts stuff, you know that do not want to be repeating the work again
any time soon.
i guess its true any time we buy something sight unseen we are rolling the dice, my problem is i can be a bit too trusting sometimes. usually when i buy a used saw in person, ill ask to do a vacuum test , that lets me remove the muffler, and i can in the exhaust port as well, if they dont to let me then i have to make a choice, most are not keen in letting you tear their saw apart , if i buy a saw online i assume that its gonna be a piston,cylinder, rings, crankshaft, crank bearings. seals, carb rebuild, needle bearings, the wear and tear items at a minimum ..so i have to get it cheap in that case.
i used to not run at wot either , till my dads saw dealer noticed the carbon and asked about it, i told him i use enough throttle to get the job done..he informed for limbs and such thats ok but if im in a real cut, its wot, after that the carbon build up wasnt a problem anymore.
but i understand that not every person who needs a saw want to have all these tools and go to all this trouble, they just want it to work, theres nothing wrong with that either,
out of curiousity, what is a good temp for a well adjusted carb in the cut at WOT
man im really sorry for your troubles boss
tomorrow will be a better day
youll get your saw rebuilt
and be wiser for it.
Rick
thats why its equipped with wideband O2s, standalone ECU, dual knock sensors. and water injection. they are tools to keep it alive and healthy ..
so why would i not do that with my 2 strokes.....so not 3 days ago i ordered a tach to compliment the infrared therm i already have.. 2 strokes are highly wound little suckers , and with all the tech and cheap as it has gotten theres no excuse for me to not go a little further to make sure you have a healthy saw or saws, i always happy to learn something new or learn something from another person
the only parts i ever used on stihl saws other than stihl was meteor and never had problems with them personally
ive learned my lesson with chinese and knock off parts..
i learned it with bmw parts, nothing is as good as those OEM bmw parts, so now i just bear it and grin when its time
to buy parts for my old bimmers. its just not worth doing the job 3 to 4 times in 2 years as opposed to doing doing it once every 10 years.
if youve ever worked on a bmw, and i mean the blood and guts stuff, you know that do not want to be repeating the work again
any time soon.
i guess its true any time we buy something sight unseen we are rolling the dice, my problem is i can be a bit too trusting sometimes. usually when i buy a used saw in person, ill ask to do a vacuum test , that lets me remove the muffler, and i can in the exhaust port as well, if they dont to let me then i have to make a choice, most are not keen in letting you tear their saw apart , if i buy a saw online i assume that its gonna be a piston,cylinder, rings, crankshaft, crank bearings. seals, carb rebuild, needle bearings, the wear and tear items at a minimum ..so i have to get it cheap in that case.
i used to not run at wot either , till my dads saw dealer noticed the carbon and asked about it, i told him i use enough throttle to get the job done..he informed for limbs and such thats ok but if im in a real cut, its wot, after that the carbon build up wasnt a problem anymore.
but i understand that not every person who needs a saw want to have all these tools and go to all this trouble, they just want it to work, theres nothing wrong with that either,
out of curiousity, what is a good temp for a well adjusted carb in the cut at WOT
man im really sorry for your troubles boss
tomorrow will be a better day
youll get your saw rebuilt
and be wiser for it.
Rick
hseII
Addicted to ArboristSite
I’ve seen saws with burned down bottom ends from running 50:1.
There’s Merit.
I personally run @ 36:1 Red Armor.
Why?
Because I’ve seen the insides after saws ran hard using each ratio & that settles it for me.
Sent from my iPhone using Tapatalk Pro
hseII
Addicted to ArboristSite
SteveSr
Addicted to ArboristSite
Looks like the saw ran with poor quality oil to cause all of the carbon buildup.
However, your "September" fuel is WAAAAY out of date! 8-12 weeks MAX in a tightly sealed can.
If this was an Ebay purchase you have a year to go back at the seller for a "significantly not as described" complaint.
