Can't Figure This One ???

[rahtreelimbs]

I worked on a Husky 55 Rancher the other day. The owner said he couldn't get the saw to run. To make a long story short, the saw had lost a lot of compression. After I tore the top-end down, I discovered that the piston ring was stuck in the piston. All the top-end parts were free of any scores or abrasions. The ring wasn't expanding at all. I got the ring free. It wasn't in too tight. I also cleaned out the carbon built up behind the ring in the ring groove. The whole top-end was dry, no oil whatsoever! I put the saw back together and now it runs great. I don't know the circumstances that led to this. What could cause the ring to get stuck-collapsed in the piston?

 

[jokers]

I`ll tell you what I think and I`ll stick with it until someone comes up with something better. Running overly rich, possibly with low grade oil, you got carbon buildup in the ring groove that was enough to restrict movement. I would guess that the ring was first stuck on one side, the piston doesn`t move in a perfect stable straight line, and as the ring became stuck further around the piston became even more destabilized. With less pressure exerted within the bore because of only one and a partial ring bearing on it you can even get sideways movement to a small degree which ultimately pushed the ring in all the way around. The same destabilized motion that pushed the top ring in caused the bottom ring to be scrubbed free of the carbon because of it`s relative position to the wrist pin. The top of the bore was dry because the top ring was no longer "wiping" the oil all the way up.

Russ the boring genius

 

[ricksvar]

Hi Rich,

Out of curiosity could you tell us what grade fuel the owner was using and oil mixture ratio?Any carb adjustment necessary?

Rick

 

[rahtreelimbs]

Originally posted by ricksvar
Hi Rich,

Out of curiosity could you tell us what grade fuel the owner was using and oil mixture ratio?Any carb adjustment necessary?

Rick

All I know is that the guy supposedly ran 50:1 Husky oil in the saw. I don't know this guy personally, he is a friend of my brother-in-law. I just offered to look at the saw. Never thought that I would get it running or that a ring would be stuck. I was also told that this saw gets loaned out occasionally. Who knows what they did.

 

[eyolf]

When I was a kid my friends and I used to mess around with snomobiles a lot; in those days everybody used dino oil at 20:1. I saw this sometimes on sleds that were abused by lots of putt-putt running...gramps using the sled to get to his fishing shelter, then maybe to the resort for another 12-pack and a pack of Raleighs.

Usually what happened eventually was one of the grandkids got on the sled, decided to do Grampa a favor and burn the carbon out. Bad idea.

Is the saw's throttle linkage right? Will it open the throttle up all the way? Does there happen to be any users that like to putz their way through light cutting with just enough throttle to keep the chain moving?

just a thought.

 

[Fish]

It is called lean seizure, and the saws days are numbered.
Anyone can take a brand new saw, and fiddle with the carb
and melt the piston, thus "sticking" the rings. The saw you are
describing, has no real future, other than a rebuild, but you need
to find out the original cause of failure, so the lean seizure will
not happen again.

 

[dbabcock]

Fish,
You overuse commas like Dennis overuses periods. Has Gypo arrived yet? Wanna plane ticket to Clearwater? Putz. Hahahaha

 

[tree monkey]

its caused by old low octane gas, does'nt burn hat enough to burn the oil

 

[rahtreelimbs]

Originally posted by Fish
It is called lean seizure, and the saws days are numbered.
Anyone can take a brand new saw, and fiddle with the carb
and melt the piston, thus "sticking" the rings. The saw you are
describing, has no real future, other than a rebuild, but you need
to find out the original cause of failure, so the lean seizure will
not happen again.

This may have been the cause. However, the piston ring came out real easy. There was no scoring or abrasions. The saw has incredible compression and runs like a bear. The saw was not running lean when I first fired it up. Go figure.

 

[Keener]

It may be a symptom of the Coriolis effect, with the ring sticking at the pin then progressively becoming stuck in a clockwise direction.
This would only be true in the northern hemisphere though.

 

[rahtreelimbs]

Originally posted by Keener
It may be a symptom of the Coriolis effect, with the ring sticking at the pin then progressively becoming stuck in a clockwise direction.
This would only be true in the northern hemisphere though.

 

[glens]

See if they've been using milk jugs for fuel containers.

 

[turnkey4099]

It may be a symptom of the Coriolis effect, with the ring sticking at the pin then progressively becoming stuck in a clockwise direction.
This would only be true in the northern hemisphere though.


I think it would also apply down there. The saw is after all upside down so the rotation should be the same.

Harry K

 

[jokers]

I have heard of the rings sticking from using milk jugs but haven`t seen it yet. Could be the deal.

Russ