MS 460 stuck rings?

[Tony Snyder]

I got a Stihl MS 460 in with low compression. I took the cylinder off and all that appeared to be wrong was that the rings were stuck. It was carefully cleaned up, put it back together, and it ran great.

You guys think too much oil would have done this or would it be from the selection of a particularly bad type of oil?

This was not a high hours saw. It still was on the worn out end of the original bar.(about 4 chains)

 

[tony marks]

one of the shps that use to be around here had a sighn. no saws worked on that use warren oil.

 

[bwalker]

Too much oil wouldnt cause it. More than likely some bar oil got in the gas tank or plastic from a improper fuel can.

 

[SilverBlue]

Many fail to allow the saw to idle for a short time after heavy duty use, they simply shut off the very hot engine allowing the excessive heat do damage.

 

[rahtreelimbs]

I had this same problem on a Husky 55 Rancher. I posted a thread regarding the same questions. The saw is still running real strong!

 

[max2cam]

Originally posted by SilverBlue
Many fail to allow the saw to idle for a short time after heavy duty use, they simply shut off the very hot engine allowing the excessive heat do damage.

I never thought about this before but it sounds plausible.

Does allowing the engine to idle after a hard cutting session draw fresh cool mixture around the piston?

I just assumed shutting it down ASAP was good policy. But maybe not.

Hopefully other members will add their 2 cents on this subject.

 

[cbfarmall]

Like 4-cycle engines, idling after heavy loads helps the piston, rings, cylinder, and exhaust to cool down slower and at more equal rates. On diesels, shutting the engine down immediately could give you a cracked head, warped valves, or even a messed up turbo.

Chris B.

 

[sedanman]

PART THROTTLE OPERATION, That's my guess.

 

[crowe]

I had the same problem with a 2101 a few years ago. A guy I cut for gave it to me because he said it froze up on him. I sprayed the cylinder with PB blaster and it loosened up after a couple of minutes but it was full of gunk. I figured someone had screwed up the mix. After I cleaned it up it ran fine real strong old saw.

 

[wak110]

And if it's the one you sold me Wade it's still going strong!

 

[firedoctor]

A buddy of mine insists on not running full throttle, (and also throttles from idle with the bar resting on the wood, but that's another story). I wasn't going to say anything until I knew for sure, but I thought it was best to always run at full throttle. Is that correct?

Originally posted by sedanman
PART THROTTLE OPERATION, That's my guess.

 

[SilverBlue]

You don’t have to operate at full throttle all the time and a slower speed equals less stress on moving parts, but too slow also means less cooling and greater possibility of plug fouling and carbon build up. As far as starting a cut from idle, well that’s just goofy.

 

[vsteel]

Is it ok to limb at part throttle? Seems like it would hurt the saw more to run at full speed when cutting 2 inch brances than it would by using it slowed down a touch. As long as you are getting your full throttle blasts in there too like when you do the acutall blocking of the main trunk.

Isn't limbing small stuff wide open amost like running the saw at no load? I thought it was bad to hold the throttle open and not have a load on it?

 

[Tony Snyder]

I basically disagree with this part throttle operation stuff. You might get away with it on your grass trimmer but I wouldn't do it on a saw.

 

[jokers]

On carbs for chainsaws you get about 1/3 the total fuel volume from the idle circuit and the rest comes from the nozzle in the venturi. So that you don`t get a lean condition at idle, there is a vacuum operated check valve in the nozzle which prevents back bleed of the idle fuel. If you are running the engine above idle but not at WOT you may not have sufficient vacuum to open this check valve fully or at all. Now you are running lean at an engine speed significantly above idle. Is this OK? Maybe for your saws but not mine. These type carbs only have Idle and WOT circuits. You are not doing your saw any favors by running it in any other state for any extended period of time. Accelerate to WOT immediately preceding contact with wood and chop the throttle when the cut is done, don`t hold it pegged until the next knot to be bumped is in reach. I believe this partial throttle condition is exactly what kills all of those carver`s saws that Yukon659 spoke of recently.

Partial throttle or mixing fuel in milk jugs was probably the cause of the stuck rings in this case, I haven`t seen any modern oil dirty enough to cause this but then what do I know?

Russ

 

[crowe]

Bill,
Yep!! thats the one. Glad to hear its still up to snuff!........Wade

 

[Tony Snyder]

firedoctor,

It is best to have the centrifugal clutch engage at no load; in other words not with the bar laying on the log. You will get away with it for a while but it will ultimately shorten clutch life.

 

[tony marks]

i cant see where theres a time, that partial throttle would be needed... after all it aint a trimmer... seems to me its either u usin the saw at wot in cut, or idling.
thats my laymans way of sayin what u said russ... just cant remember a time when half throttle was even called for...
in my experience.
ps. mabe with a climbing saw, but i doubt it.