Illustrated Stihl engine failure analysis guide

[Definitive Dave]

This is black and white but is a high res scan from the nicest of the three different versions in my hardcopy literature collection.

Work is underway on a color version by another member who has promised to score a number of identical new pistons in a new cylinder to show the differences

SCIENCE!!!
Dave

 

[Lootbug]

Excellent, thanks for posting it up.

 

[Brian Simonseth]

I pulled this piston from a 044 10 mm saw today

 

[Philbert]

Verrrry interesting!

Some nasty looking pistons in that book.

Never heard of 'snow / water score'!

Philbert

 

[Definitive Dave]

I pulled this piston from a 044 10 mm saw today

Is that a hole through the top of the cylinder down to the pin boss?
It looks like one of those pesky neighbor kids shot your piston from the inside with a BB gun

 

[cus_deluxe]

this is great info dave thanks for posting!

 

[cus_deluxe]

I pulled this piston from a 044 10 mm saw today

so is that a transer port?

 

[huskihl]

I pulled this piston from a 044 10 mm saw today

I've always heard that type of damage is from water

 

[cus_deluxe]

I've always heard that type of damage is from water

Ive always heard its from too much nitrous....

 

[Brian Simonseth]

Is that a hole through the top of the cylinder down to the pin boss?
It looks like one of those pesky neighbor kids shot your piston from the inside with a BB gun

That's the way she came out I first thought it was from a piston stop then I went thru that pdf above it also has a frozen top ring

 

[SixGun]

Thanks Dave, Great info

 

[Philbert]

I find these types of illustrated failure analyses very interesting and educational. It looks like some of the examples are from customer-owned products, and some were deliberately run to failure in a test setting.

If you read STIHL's comments, it is pretty clear where they stand on porting, mods, and coloring outside the lines . . . .

Philbert

 

[atv1965]

Excellent read, thanks very much!!!!
Andy

 

[Wagnerwerks]

I find these types of illustrated failure analyses very interesting and educational. It looks like some of the examples are from customer-owned products, and some were deliberately run to failure in a test setting.

If you read STIHL's comments, it is pretty clear where they stand on porting, mods, and coloring outside the lines . . . .

Philbert

I don't know if you guys all know this, but Philbert REALLY likes info on saws. .

 

[lumberjackchef]

Verrrry interesting!

Some nasty looking pistons in that book.

Never heard of 'snow / water score'!

Philbert

Sure are! Howdy there Philbert!

 

[Poleman]

Good post Dave!!!!!!!! Thanks!!!!!!

 

[Nitehawk55]

I actually had a hand in the making of that manual which was done at the Stihl Canada Tech shop by the head service manager Dave Ellis who I worked with on various projects and service schools . I had several of those manuals but I just gave my last one away not long ago to a young fellow interested in learning about saws . It's an excellent diagnostic manual for what causes different failures in 2 stroke engines , something the company felt would help our dealer service Tech's .

Dave could build some wild hot saws too BTW , He used to compete in Ontario , Quebec and in Michigan and I think Ohio and IN as well . He won quite a few classes too .

 

[heyduke]

I find these types of illustrated failure analyses very interesting and educational. It looks like some of the examples are from customer-owned products, and some were deliberately run to failure in a test setting.

If you read STIHL's comments, it is pretty clear where they stand on porting, mods, and coloring outside the lines . . . .

Philbert

i tend to agree with stihl. it makes me chuckle to think that guys are sure they're smarter and more skilled than the engineers and techs who put these saws together. sure, if you know what you're doing you may make a saw perform a little better for special purposes. if you know what you're doing. most guys are doing good to change a cylinder and piston without causing a catastrophic failure. i'm working on an echo 670 now. the monkey cross threaded the spark plug, then had to install a thread insert. the bottom part of the thread insert broke off, did a number on the piston top, the rings, the main bearings and case. after that he cross threaded the insert and gave up. i'm sure he thinks he's a wizard. did you notice the piston damage attributed to a muffle modification?

 

[PogoInTheWoods]

Just ran across this today, Dave. Good stuff. Thanks.

it makes me chuckle to think that guys are sure they're smarter and more skilled than the engineers and techs who put these saws together.

Too bad those skilled techs and engineers had yet to design a consistently effective pre-filter/air filtration system across the board that could have kept a lot of that 'abrasive debris' from assisting in the creation of some of those illustrations. A weak spot for Stihl over the years.

 

[akennyd]

Thanks for the info!! I have a question though... How do you over-rev a chainsaw engine? Revving without a bar and chain? Extended revving out of wood? Incorrect tune (too lean) and revving out of wood? Saw mods?

Any thoughts?

Thanks,
Kenny