Found inside ab 028 super

[Ccarignan]

So the other day I was buying a new trimmer and a guy in line was wondering what he could get for his 028 as trade-in value for a new saw, I tell him if they don't give you $50 I will, I like to tinker and rebuild old saws as a hobby, so I came home with a new (old) saw. It has a broken pull cord and he says it's tough to start, I retie the cord give it some pulls and there's nothing, check the plug and it's dry. I'm planning on doing some porting anyway so I open it up today and find a piston that looks like this and some wild chamfer on all the ports. There's nothing rattling around the crank case.. did somebody try to window port the piston here?

 

[pioneerguy600]

Looks like that ole girl wore its self plum out.

 

[Maintenance supervisor]

View attachment 979630View attachment 979631
So the other day I was buying a new trimmer and a guy in line was wondering what he could get for his 028 as trade-in value for a new saw, I tell him if they don't give you $50 I will, I like to tinker and rebuild old saws as a hobby, so I came home with a new (old) saw. It has a broken pull cord and he says it's tough to start, I retie the cord give it some pulls and there's nothing, check the plug and it's dry. I'm planning on doing some porting anyway so I open it up today and find a piston that looks like this and some wild chamfer on all the ports. There's nothing rattling around the crank case.. did somebody try to window port the piston here?

OEM? Awfully thrick rings?

 

[Wood Doctor]

That could be the worst worn out Stihl 028 piston that I have ever seen. Gasp!
Once that skirt section broke off, the rest must have been really loud noise. I'm surprised the cylinder looks that good.

 

[Ccarignan]

That could be the worst worn out Stihl 028 piston that I have ever seen. Gasp!
One that skirt section broke off, the rest must have been really loud noise. I'm surprised the cylinder looks that good.

It must have vaporized if it broke, there's nothing in the crankcase, I'll split it later today or tomorrow and update.

 

[Ccarignan]

I agree that it looks broken, but I would expect something to be in there and more damage on the inside, here's some wear on the crankcase.

 

[Ccarignan]

And this roller has all it's pins

 

[Ccarignan]

OEM? Awfully thrick rings?

It's a mahle, numbers 46L16 on one side, R064 and 138 on the inside

 

[pioneerguy600]

That could be the worst worn out Stihl 028 piston that I have ever seen. Gasp!
One that skirt section broke off, the rest must have been really loud noise. I'm surprised the cylinder looks that good.

I have seen many that broke and continued running, my theory is that the skirt breaks off in tiny bits starting at the very bottom of the skirt and works its way upward. The ones I have seen that broke off in one big piece jammed the crank counter weights and the saw stopped immediately. YMMV..

 

[TheTone]

What's happening on the right edge of the picture? It looks like someone mended a gouge on the cylinder wall with JB Weld.

 

[pioneerguy600]

How thin is the skirt on the edges where the piece is missing, I have seen them tin foil thin and on others but still a good bit thick.

 

[Oletrapper]

And this roller has all it's pins View attachment 979666

Got all its pins but it appears that the cage is mangled. OT

 

[Ccarignan]

What's happening on the right edge of the picture? It looks like someone mended a gouge on the cylinder wall with JB Weld.

Just some scratches, there is a good gouge on the left side.

 

[Ccarignan]

I swear there was a comment asking for pictures of the bigend of the rod moved to each side so here's that along with a flywheel side bearing, still working on the clutch, need some pb blaster

 

[Ccarignan]

 

[Oletrapper]

View attachment 979873

Just wondering, Is there any reason you haven't cleaned the little guy up before working on it? Looks to be in pretty bad shape to me. Also appears to have a crack in the case in one of the photos. Hard to tell with all the debris. jmho OT

 

[stihltech]

Bad air filter maintenance wears the piston skirt and this is the result. Run a small piece of paper towel around the inside of the crankcase a few times to clean it out. Get a GOOD look at the crank bearing cages. No missing pieces. No play in the crank rod and side bearings. New crank seals are recommended. If you have any scratches into the cylinder wall it may be toast. Aluminum transfer can be removed. Vacuum and pressure test after assembly.

 

[TRTermite]

Just wondering, Is there any reason you haven't cleaned the little guy up before working on it? Looks to be in pretty bad shape to me. Also appears to have a crack in the case in one of the photos. Hard to tell with all the debris. jmho OT

I kind of understand. A 170 Stihl was dropped off last nite as a "GIFT" said the gas tank had a Leak but it ran. Wish I would have put gas in before tearing it down and cleaning it up. Cylinder/muffler/carb still attached but I did get in a hurry and the tank does not leak so now go back together and do things the other way. A bunch of tidbits to learn from the comments here, Thanks everybody.

 

[TRTermite]

I kind of understand. A 170 Stihl was dropped off last nite as a "GIFT" said the gas tank had a Leak but it ran. Wish I would have put gas in before tearing it down and cleaning it up. Cylinder/muffler/carb still attached but I did get in a hurry and the tank does not leak so now go back together and do things the other way. A bunch of tidbits to learn from the comments here, Thanks everybody.

Ended up being a simple 'OLE duck bill malfunction.. I won't tell him what the problem was 'cuz he never pays his bills and figure "Devine intervention is good for the goose as well as for the Gander". Gave him 20$ for my conscience. What a grungy saw it WAS. Still need to address the oiler , seems a bit lacking.