Piston Failure Cause

[drf255]

I have seen the exact same piston damage on two 026's and an 024.

I always assumed (as nmurph mentioned) it was piston slap and tickle.

Good luck with the project !

Maybe some crazy canuck will send you an 038 mag cylinder to put on this saw. ( winkwink - just kidding )

Funny. Haven't seen it yet bro.

 

[sawsawsaw]

Hmmmm....... Hopefully this week !

That busted piston and oil pump should keep you entertained until it arrives !

 

[jl4c]

Pessimist.

'Pessimist' is the disparaging name that optimists give to realists. ;-)

 

[juttree]

Did a friend's 260 this past summer with the same piston failure.

 

[HarleyT]

Wow, Why don't you just merge this thread with your other one? Then that would clear things up a tad....

 

[drf255]

Wholly $hit.

Exact.

I'm gonna run a few beads of 4047 inside the piston.

 

[big t double]

'Pessimist' is the disparaging name that optimists give to realists. ;-)

 

[HarleyT]

I think I know what led to this saw's destruction, I may be wrong though.

Under the clutch, the oil pump drive tit snapped off halfway down. It also ground down the oil pump. The surface almost looks like it was machined with a mill.

I think the prior owner put a non-pro clutch drum with no notch for the drive on and then tightened everything down. The clutch cover then bent the pump drive and then the saw was run with this amount of drag on it. So much that it ground metal down.

I think this was the cause.

The cause of what?

 

[HarleyT]

Sounds like there are many little fingers involved into this "Frankesaw's" demise.............

 

[jl4c]

View attachment 398171

I like it!

 

[HarleyT]

You are starting a bash thread against someone here?

 

[angelo c]

You are starting a bash thread against someone here?

Relax Brushy....breathe slow...you can do this.

Just behave and all will be well and forgiven....calm those demons.

 

[HarleyT]

Relax Brushy....breathe slow...you can do this.

Just behave and all will be well and forgiven....calm those demons.

But they won't leave me alone!!!!!!!!!! They come to me all of the time!!!!!!

 

[HarleyT]

Who Is "Brushy"?

 

[angelo c]

Who Is "Brushy"?

We're cool if you're cool.

 

[fearofpavement]

The ground down oil pump is unrelated to the piston failure. Most pistons I have seen that have the skirt worn thin and broken have been on the intake side. Not sure of the reason, just my experience.

 

[Bilge Rat LT 20]

The intake side of the piston takes more of the thrust load. Something about rod angle/crank throw and power impulse.

 

[nmurph]

Trash abrading the skirt as it enters the cylinder

Never heard the thrust load thing, but it could well be.

 

[MarylandGuy]

Funny, the exact same thing happened to my 026 last year. It has been sitting for a while waiting for me to get time to fix it. I tore the saw down a few weeks ago and found my piston looking the same way. I was able to clean up the cylinder, put a Meteor kit in it and slapped it all together last night. Hopefully I will fire it up tomorrow provided we don't get a lot of snow.

 

[drf255]

The ground down oil pump is unrelated to the piston failure. Most pistons I have seen that have the skirt worn thin and broken have been on the intake side. Not sure of the reason, just my experience.

The intake side of the piston takes more of the thrust load. Something about rod angle/crank throw and power impulse.

Trash abrading the skirt as it enters the cylinder

Never heard the thrust load thing, but it could well be.

It's the exhaust side on this saw.

Now that I'm investigating, this damage to this model is seeming more and more common.