What happened here?

[andrethegiant70]

Hi, Gents, I thought I'd bring this one to you! Seems appropriate for a Saturday Night. I'm redoing the top end on an 044. Check out the pics I've attached. The saw was give to me siezed but when I popped the muffler off I was amazed to see a perfect piston. After disassembling it, it appears that the top of the piston has hung up on the top of the exhaust port. Bearings are smooth with no play. The rod has no vertical play at all, and maybe just a litlle laterally. Piston pin is tight. Other than the obvious notches on the piston and cylinder, both are in perfect condition. The only thing I can surmise is excessive skirt wear, but with such a clean piston I just don't see it.

Think I can save any of it?

 

[ozflea]

Looks like it swollowed a screw you can see the thread imprint.

Mc Bob.

 

[rahtreelimbs]

It appears that something may have broke off. Did you find any pieces in there?



As to what happened there............don't have a clue! This one is for Lake, Spike or Thall. I see no reason once that piston is smoothed out why the saw can't be saved. I would make sure the ring isn't hung up in the groove and I would also take a good, close check at the bore to make sure more doesn't want to chip off.

 

[stihltech]

Ufo

Looks like an unidentified foreign object. The person before you knows what it was.
I agree with the screw theory. Thoroughly inspect the internals. Clean the top of the piston and look for cracks.
I doubt the saw was running when this happened. The piston would be pieces.
Looks like a candidate for a bit of porting on the exhaust.

 

[andrethegiant70]

Well, I can't say that I saw anything when the jug came off. Please notice that the two hits on the piston correspond to the nicks on the jug. I think what you folks might be thinking are threads are repeated strikes as the user tried to pull the saw over. There don't appear to be any hits on the top of the piston, but I'll clean things up in the morning be sure.

I like your ideas on FOD, I'll look into that a bit more.

 

[Trigger-Time]

IMO, I would replace piston.....looks well worn to me, not counting
the imprint marks.

 

[RaisedByWolves]

I got this one!




The PO used a bolt through the exhaust port to act as a piston stop so he could remove the flywheel/clutch.




This is common on lil airplane engines and somehow the practise got used on this saw.........


.

 

[andrethegiant70]

OOoo! RBF, that theory has some real merit! It would fit with the likelihood that the damage happened while the saw was not running! Although I will say that it would be unusual to use 2 bolts (there are two damage marks) as piston stops.... I suppose the PO could have used a flat piece of metal and because of the shape of the port it would produce the existing damage.

 

[oregonlumber]

just one thing i see, is that metal shavings on top of the piston or is that just from the flash on the camera.

 

[livewire]

OOoo! RBF, that theory has some real merit! It would fit with the likelihood that the damage happened while the saw was not running! Although I will say that it would be unusual to use 2 bolts (there are two damage marks) as piston stops.... I suppose the PO could have used a flat piece of metal and because of the shape of the port it would produce the existing damage.

One to loosen...one to tighten.....

 

[zzrjohn]

Looks to me like the top ring as been pinched in the ring groove/land, I'd fit a least a new piston, but would probably go for a new jug/piston or bb kit.

 

[carvinmark]

I got this one


The PO used a bolt through the exhaust port to act as a piston stop so he could remove the flywheel/clutch.




This is common on lil airplane engines and somehow the practise got used on this saw.........


.

I have never seen this before but I think RBW is right.

 

[oldsaw]

OOoo! RBF, that theory has some real merit! It would fit with the likelihood that the damage happened while the saw was not running! Although I will say that it would be unusual to use 2 bolts (there are two damage marks) as piston stops.... I suppose the PO could have used a flat piece of metal and because of the shape of the port it would produce the existing damage.

Maybe he forgot something and went in twice. I've done it before. Just did it, forgot that little rubber doohickey on the 066's oil pump. Had to pull the clutch again.

Nice call RBW, I'm liking it.

Mark

 

[oldsaw]

One to loosen...one to tighten.....

Doh, that's even easier than mine, and makes perfect sense.

Mark

 

[andrethegiant70]

Case Closed!!

I think you guys have done it! I went out to the shop this morning to look at the cylinder more closely and the marks on the cylinder do indeed look like threads!

Holy mackerel! That's a bit goofy to shove bolts into the combustion chamber of your $700 saw! I figure I'll replace the piston and cylinder (I have a good used cylinder and I'll use a new piston). RTL, you might be right, the piston might be saved but I'm going to put this saw up for sale and it would be a bummer if the new owner had chunks out of his piston. I'm tempted to keep it because I've heard such great things about the 044, but I'm genuinely finding that I just don't use saws between 60 and 80cc. They're too heavy for a comfortable firewood saw and they're not big enough to mill with. But this is probably another thread.

I'm calling this case closed, though! Nice work, gents.

 

[Lakeside53]

Maybe he forgot something and went in twice. I've done it before. Just did it, forgot that little rubber doohickey on the 066's oil pump. Had to pull the clutch again.


Mark

ah ha! and you said you didn't need to follow my guide!!!!

 

[joesawer]

How much for the saw as is? I am interested in a 44 builder.

 

[oldsaw]

ah ha! and you said you didn't need to follow my guide!!!!

Ha, no, I just noticed the "leftover part" on the workbench. It was black, and on black spot on the cardboard I was working on. After torquing the clutch on, I rolled the saw over and the little rubber bit rolled onto a clean part of the cardboard. I made a scatalogical reference, then knocked the clutch off again. Rinse, lather, repeat. I'm pretty good at it now, though. I could be a Stihl certified, 066/660 oil pump replacement expert. Not much call for that, however. I'll keep my regular job.

Mark

 

[andrethegiant70]

Hi, Joe! I would consider it but, as you can see, I'm eyeball deep in the project, with parts standing by and more on the way. The saw will get get a new (used) tank, rewind (nothing wrong with it, I just have a nicer-looking one), a better looking top cover, good used cylinder, new piston, carb rebuild, and a VERY meticulous bath.. I'll cut with it a few days to make sure I got it all right and then it goes on the block!

This project was a "go" since I had a good parts saw. The top end appears to have the only mechanical problem, the rest is just cosmetic. I bought it for $100 with a nice 24in bar and chain thinking it was a straightforward fix ....like I said, I just don't have a use for it. It's overkill for firewood and I'd be abusing the saw if I milled with it.

What I'd REALLY like is to find a good 394/395/066/660 project! Anyone got a basket case? I can BUILD stuff wih a saw like that!

Thanks for your input on this one, peeps. Good bit of sleuthing!

 

[ciscoguy01]

Sooooo...

I got this one!




The PO used a bolt through the exhaust port to act as a piston stop so he could remove the flywheel/clutch.




This is common on lil airplane engines and somehow the practise got used on this saw.........


.

The other day I was going to pull my flywheel to clean it... How exactly do you get the flywheel off??? I'd never though of doing that with the bolt in the cylinder, but how else would you do it??? opcorn: