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Chainsaw cause of death?

#1

oldlawnguy

oldlawnguy

Gentlemen,

Any insight on cause of this catastrophic piston failure? (pictures attached)

Cylinder looks well lubed. I did noticed on disassembly the grommet c-clamp (came loose) was not attached to large diameter part of grommet that attaches to cylinder and seals with c-clamp.

Pretty ugly scoring.

The failure occurred while the chainsaw was doing a horizontal leveling (saw sideways, bar level to ground) cut of a large tree. It was humming along and literally just stopped like I killed the switch. I let it cool a bit, and it almost started a few times until it seized up.

Does not look like it was running lean, if anything with the oil in cylinder looks a little fat. Cylinder has minor scoring only beneath the intake.

Scratching head

Thanks

Attachments











#2

M

mechanic mark

What brand & model chainsaw? Have you been using OEM 2 cycle oil recommended by manual?

Replace oil pump along with failed parts.


#3

StarTech

StarTech

Kinda looks like it inhaled a screw or other forgien hard object. Also check for bearing failure.


#4

I

ILENGINE

No question that was foreign object ingestion.


#5

B

bertsmobile1

For the benefit of you understanding how to diagnose the failure as Star & Ilengine have diagnosed correctly .

All of the damage is on the bottom of the piston and not on the top.
That indicates something got into the engine that was too big or heavy to pass from the crank case through the transfer ports & into the combustion chamber
Further more all of the damage is on the induction ( carb side ) so that confirms a foreign object .
The gouges are deep & sharp so it has to be some thing metallic, like a screw from the carb butterfly or a lump of gravel.
The piston is complete with no horrizontal cracks , deformation or scuffing so that rules out a bearing failure or bearing break up
There is almost no damage to the crankcase but the image is too small to properly inspect it .
What caused the damage should still be in the crankcase or even under the piston.
The other thing that causes damage like this is a piston pin clip falling out but usually that shows some gouges on the side before it drops into the crankcase and you usually find it chewed up in the case plus the piston can then shift sideways so you get scuffing on the side of the piston .
You could not discount this as the saw was running fine till you tipped it sideways

Back in the old days manifolds used to bolt onto the cylinder and owners used to get the screws mixed up so you could insert a spring that was too long and broke through the cylinder.


#6

Hammermechanicman

Hammermechanicman

Definitely sucked in some junk.



It'll probably buff out?


#7

oldlawnguy

oldlawnguy

bertsmobile1 said:
For the benefit of you understanding how to diagnose the failure as Star & Ilengine have diagnosed correctly .

All of the damage is on the bottom of the piston and not on the top.
That indicates something got into the engine that was too big or heavy to pass from the crank case through the transfer ports & into the combustion chamber
Further more all of the damage is on the induction ( carb side ) so that confirms a foreign object .
The gouges are deep & sharp so it has to be some thing metallic, like a screw from the carb butterfly or a lump of gravel.
The piston is complete with no horrizontal cracks , deformation or scuffing so that rules out a bearing failure or bearing break up
There is almost no damage to the crankcase but the image is too small to properly inspect it .
What caused the damage should still be in the crankcase or even under the piston.
The other thing that causes damage like this is a piston pin clip falling out but usually that shows some gouges on the side before it drops into the crankcase and you usually find it chewed up in the case plus the piston can then shift sideways so you get scuffing on the side of the piston .
You could not discount this as the saw was running fine till you tipped it sideways

Back in the old days manifolds used to bolt onto the cylinder and owners used to get the screws mixed up so you could insert a spring that was too long and broke through the cylinder.
Click to expand...
Thanks all. You nailed it! On further inspection its missing the piston retaining ring (~$1 part). You can see small blobs of molten steel in cylinder, but I cannot find any pieces of ring (even looked in muffler). It turned over a few times after I let it cool down so could it have ejected what was left? Saw was working great for an hour cutting up big tree.

Given the cylinder scoringe (see attached) is below the intake can I buff it out and give it a go with a new piston, ring and retainers?

I'm not a pro so would rubbing out with #0000 steel wool be an option or should I try something else?

Thanks!

Thanks

Attachments









#8

B

bertsmobile1

We have all been there before
And the simple answer is no
The piston & cylinder are toast
You can get reasonable quality cylinder & piston kits from Huztl direct from China or buy much more expensive kits locally.
If buying from China you will need to know the Husqvarna equivalent model number and check the images carefully to make sure the carb mountings are the same .
If you are lucky then there will be a bigger bore kit that will fit because they are only a couple of dollars dearer than the standard size so end up with a horse or two more grunt.
Avoid anything on evilbay or ammo zone as that are a lucky dip as to the quality some are good & others are stuff the vendor bought as scrap metal because they failed quality control
I usually replace the bearings just in case the debris bouncing around inside damaged the oil seals
You don't want to spend 3 hours rebuilding the saw only to find the crank leaks .


#9

S

slomo

I always shake/swirl the fuel jug up nicely prior to filling any 2 smoker tank.

Seen numerous boats where the guys would dump a bottle or two of oil in
the tank. All that oil settles to the bottom. Must be a foot of oil down there. Oil never gets mixed up.

slomo


#10

oldlawnguy

oldlawnguy

bertsmobile1 said:
We have all been there before
And the simple answer is no
The piston & cylinder are toast
You can get reasonable quality cylinder & piston kits from Huztl direct from China or buy much more expensive kits locally.
If buying from China you will need to know the Husqvarna equivalent model number and check the images carefully to make sure the carb mountings are the same .
If you are lucky then there will be a bigger bore kit that will fit because they are only a couple of dollars dearer than the standard size so end up with a horse or two more grunt.
Avoid anything on evilbay or ammo zone as that are a lucky dip as to the quality some are good & others are stuff the vendor bought as scrap metal because they failed quality control
I usually replace the bearings just in case the debris bouncing around inside damaged the oil seals
You don't want to spend 3 hours rebuilding the saw only to find the crank leaks .
Click to expand...
I'll replace the cylinder as well. It's $57.25 from the local distributor I use up here in Boston. Cheaper than most other online parts places who have pretty high markup. I avoid the shipping $ and pick it up myself. Don't mind using local and paying more as they have taxes, employees, and quality control in their supply chain. Half the fun is rebuilding and the other half is getting it to work.

Yes HeeHeeBay is great for stuff you don't want to work and I only buy stuff on AmIGone that you can return. I have gotten decent stuff like fuel lines, bulbs and fuel filters there. Even found a $15 replacement carb for weedwacker, because I could not find carb kit on noname carb. I smile every time I open up a 2 cycle engine and see a Walbro carb. I get a $10 Walbro carb kit not those knockoff miss kits online.

Thanks again for helping and giving back with your knowledge and expertise to and old DYIer.


#11

B

bertsmobile1

That is an attitude worthy of applause, pity more don't think like that .
While I do like to buy local and even more from small retailers who have a higher employee to turn over ratio but when it comes to hand held parts that is not possible down here.
I have had this out with numerous franchise reps ( not the dealers, their reps ) but it falls on deaf ears.
Hard to make people who have been born into money and work for bosses who have also been born into money that extortion is not a viable long term business plan.
A piston for a Rancher 55 is $ 75 ( Aus) then add another $ 195 for a barrel + another $75 for the bearings and the parts come to 1/2 the new price before you add my $ 120 for the 2 hr of labour .
The business model down here is force people to buy new where there is 300 % of mark ups by the time the customer opens their wallets by not keeping adequate stocks of parts and massively inflating the price of parts .
Their answer is to spend a fortune trying to convince people to buy a quality brand like Husky or Stihl but in the long run, they have made them unrepairable so little benefit for the consumer over buying a throw away chain saw then spending $ 200 with me to make them work properly or just buying a new throw away every time they need one as the big glass fronts will sell you a 20cc 12" saw for $ 99 ( around $ 60 US ).


#12

oldlawnguy

oldlawnguy

You got me going...

It's the same up here, are you from down under? If so, been there and it's an absolutely beautiful place along with New Zealand.

Seems like a disappearing art of building relationships and retail customers. Dunno seems like certain people are afraid of hard work or thinking outside of the box. Hope it's not the same today on the commercial side too with margin and fix/replace.

I've found as an average schmo that hand held gas power equipment that is 10-20 years old is pretty fixable compared to that one and done junk at Home Dumbo or Hazard Fraud that I refuse to buy. I'm not buying into the lithium battery extortion stuff either. Gas or an extension cord still work just fine for me.

On the flip side you have people that want to sell you their equipment that doesn't work cuz they broke it and/or tried to fix it, but want working retail price for it. :^)

You could probably have a good go at teaching a 6 week 12 hr. small engine repair class twice a year (right before spring and right before winter). $99/student. I'd bet you could get at least 20-30 homeowners to sign up. Start small then you can go and teach it online. Guys will love it as a great XMAS gift from the Mrs. Let that sink in with the franchise reps...


#13

M

mmoffitt

"FOD"


#14

Hammermechanicman

Hammermechanicman

Ever been on a FOD walk?


#15

M

mmoffitt

Hammermechanicman said:
Ever been on a FOD walk?
Click to expand...
yes sir! USAF Crew Chief..amazing what falls off of stuff....in all kinds of weather


#16

B

bertsmobile1

oldlawnguy said:
You got me going...

It's the same up here, are you from down under? If so, been there and it's an absolutely beautiful place along with New Zealand.

Seems like a disappearing art of building relationships and retail customers. Dunno seems like certain people are afraid of hard work or thinking outside of the box. Hope it's not the same today on the commercial side too with margin and fix/replace.

I've found as an average schmo that hand held gas power equipment that is 10-20 years old is pretty fixable compared to that one and done junk at Home Dumbo or Hazard Fraud that I refuse to buy. I'm not buying into the lithium battery extortion stuff either. Gas or an extension cord still work just fine for me.

On the flip side you have people that want to sell you their equipment that doesn't work cuz they broke it and/or tried to fix it, but want working retail price for it. :^)

You could probably have a good go at teaching a 6 week 12 hr. small engine repair class twice a year (right before spring and right before winter). $99/student. I'd bet you could get at least 20-30 homeowners to sign up. Start small then you can go and teach it online. Guys will love it as a great XMAS gift from the Mrs. Let that sink in with the franchise reps...
Click to expand...
I consider myself quite priviledged to have been born here & hope to pay the country back regardless of the politicans trying to make every one rash the place.
And yes , some time , probably around 20 years ago the accountants worked out that they made a lot more money overall by sending the company on the down hill slope to oblivion converting from quality products with a high mark up to trash with a much lower margin in the hope that greater sales will result in higher overall turnover.
For this to work, the buying public have to continually replace goods which funny enough in the 50's & 60's accountants used to call "consumer durables".

The big problem is to the mug customer the costs are almost the same between buying quality & servicing it properly & buying trash & throwing it away every season or so .
However the cost to the planet of the latter is enormous .
It costs less than 10% more to make a durable long lasting mower as it does to make a throw away but the resource costs are almost identical.
So we make millions of tons of steel , aluminium & plastic to be used a few times then tossed into landfill.
It really is criminal .


#17

VRR.DYNDNS>BIZ

VRR.DYNDNS>BIZ

ILENGINE said:
No question that was foreign object ingestion.
Click to expand...
agree


#18

oldlawnguy

oldlawnguy

bertsmobile1 said:
I consider myself quite priviledged to have been born here & hope to pay the country back regardless of the politicans trying to make every one rash the place.
And yes , some time , probably around 20 years ago the accountants worked out that they made a lot more money overall by sending the company on the down hill slope to oblivion converting from quality products with a high mark up to trash with a much lower margin in the hope that greater sales will result in higher overall turnover.
For this to work, the buying public have to continually replace goods which funny enough in the 50's & 60's accountants used to call "consumer durables".

The big problem is to the mug customer the costs are almost the same between buying quality & servicing it properly & buying trash & throwing it away every season or so .
However the cost to the planet of the latter is enormous .
It costs less than 10% more to make a durable long lasting mower as it does to make a throw away but the resource costs are almost identical.
So we make millions of tons of steel , aluminium & plastic to be used a few times then tossed into landfill.
It really is criminal .
Click to expand...
Yeah tongue and cheek humor on the small engine repair courses... although some folks make decent $ on their YouTube channel.

It's the typical short term focus (earnings report every 13 weeks) .vs over long term gain.


#19

B

bertsmobile1

Once upon a time companies made products.
Now they make profits any way they can, be it cheating on their creditors, stealing from their workers pension funds, closing factories & doing real estate developements , importing what they used to make , renting out their brand name or perish the thought actually making a saleable product


#20

M

mmoffitt

It's called business, some of it being quite unsavory....


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