Stihl 251 newbie chainsaw problems?

[nuke4u]

Hi all,

First time poster and new homeowner spending my first winter burning wood and trying to chop it...unsuccessfully. I recently bought a Stihl 251 and wanted to try bucking some wood last night...but my chain seized up. This was my 1st time using the saw, and the saw was fueled and filled with bar oil from the power shop. Weather was probably in the low 40s, so not that cold, although I never changed the air intake to winter mode.

So I did read the manual and didn't have the chain brake on, but it seems like I have symptoms of that kind of thing happening. After trying to buck some wood, it would seize up in the wood very easily (but not pinching), and maybe my 1st mistake was here---when in the middle of the log and it was seized I was trying to revv it to get it going, but nothing would happen until I pulled it out of the log and started again from the outside. Also, I tried checking to see if the chain was shooting oil out on the ground but couldn't really see anything (too cold?); but at least the reservoir was full of bar oil.

After 10 minutes or so of binding up in logs very easily, I turned the saw off and came back after 15 mins or so. When I restarted the saw the chain wasn't turning, and the brake was off so that wasn't the problem.

I opened up the saw later after it cooled down and found that I couldn't pull the chain by hand, and the sprocket would not turn. I took off the sprocket and found that the edge of the drum of the sprocket was melted to the guard shield plastic slightly,so there must have been lots of heating going on, probably when I was revving bound up in the wood. Maybe the chain brake strap was stuck on the drum even when it was in the off position, but I'm not sure.

I cleaned up the melted plastic (little bit of sanding on the outside of the sprocket drum) and now the saw seems to rotate freely again, so that's good. But I don't know if I toasted some other internal components...what do you think? I haven't started the saw up again yet, but I may have to take it back to the Stihl shop for repairs if you think I should.

I wanted to know what caused my new saw to bind up so easily in the logs, what could have caused the sprocket to seize up like that. Also, maybe my sawing technique is bad?

Thanks for any advice,

Bill

 

[ErikR]

I'm sure some more qualified saw experts will give their opinions soon, but I have a couple of questions for you... Just so I have a better idea of what you were doing.

How big were the logs you were trying to cut? Were they flat on the ground, or was the something under one end? How deep in the log were you when the saw stalled? Are you sure the log wasn't pinching the bar?

You can check to see if the oiler is putting out oil by running your saw and holding the bar tip near a piece of cardboard. You should see some evidence of oil being flung off the bar tip.

 

[osagebow]

Overtensioned chain? Ask the shop guy for a tutorial. No shame in that, wish I did.

Good luck getting ahead in your stacks - hard but worth it!

 

[nuke4u]

Small logs, just testing out the saw...like 12 in or less. And the logs were sitting on the ground, I was just trying to cut through halfway and then roll them over. So would revving with a stalled saw in a log cause plastic to melt?

 

[BrotherBart]

Were you going into the cut with the saw running flat out, or slower?

 

[salecker]

Sounds like the brake was on....though you mention a couple of times it was off.
Could you explain how you know it was off?
Now to back up a bit,is this your first saw?If it is you should try and find someone that does a lot of work with a chainsaw and have them watch what you were doing,and then have them give you some lessons about maintaining and using a saw.
If you bought the saw from a reputable Stihl dealer,it would have been ready to use with no defects.
I still believe the answer is in the chain brake,and how you determine on whether it is on and off.
Thomas

 

[Teddi]

The plastic melted because the clutch was burning up. Whether the brake was on or off, if you're revving a saw and the chain is not turning, the clutch is being burned up causing massive heat at the bar mount/clutch cover. It's possible that the chain wasn't moving due to either having too much pressure applied to the bar or it could have been pinched.

Edit - after re-reading your first post, I think your chain was way too tight. You still better get the clutch looked at by the dealer. Good Luck!

 

[Jags]

Are you familiar with how tight to tension the chain? And was it adjusted properly? My bet is chain way too tight.

 

[AroostookDave]

There is one other thing that will really heat up a saw - could you have put raw gas in by mistake?

 

[salecker]

I still think it's the brake,as long as the saw came from a reputable dealer.He said it was his first time using the saw so the chain should have been tensioned right.
A lot of people set the brake befor they set the saw down.Might be SOP in the shop.....OP gets home with his new tool that he has never used.....wants to try it out and starts it reves it up nothing...revs some more.... maybe minute total now... read the manual, try the brake it comes off try cutting but now the clutch has been damaged and it starts heating up maybe the brake has been on once in a while because nothing is working so OP keeps trying it one way or another...result needs clutch brake band plastic cover and some friendly advice on using and maintaining a saw.
But i could be wrong,saw may have come from a shop that has some kid installing bars and chains,filling the gas and oil.And when asked about using the saw they say ``i dunno seems easy``
Thomas

 

[Jon1270]

So would revving with a stalled saw in a log cause plastic to melt?

Sure it would. If the engine is spinning but the chain isn't moving, or if the chain moves a little but is prevented from moving as fast as it should, then the clutch shoes are rubbing furiously against the inside of the clutch drum, creating all sorts of unproductive heat and friction.

It's easy to overtighten the chain, causing it to bind and thus the whole cascade of consequences you observed, but anything that keeps the chain from moving smoothly and easily in the bar could have the same effect -- could be a plugged bar oiler, or maybe you got the wrong kind of chain (pitch or gauge) by mistake.

 

[NH_Wood]

Sure it would. If the engine is spinning but the chain isn't moving, or if the chain moves a little but is prevented from moving as fast as it should, then the clutch shoes are rubbing furiously against the inside of the clutch drum, creating all sorts of unproductive heat and friction.

It's easy to overtighten the chain, causing it to bind and thus the whole cascade of consequences you observed, but anything that keeps the chain from moving smoothly and easily in the bar could have the same effect -- could be a plugged bar oiler, or maybe you got the wrong kind of chain (pitch or gauge) by mistake.

This was a possible thought here too - not likely in this case, but I worked on a Stihl 018 that did the same thing and this was the issue - but, that was an old saw with lots of bad adventures with previous owners - the chance of this from the shop seem unlikely, but possible. Bad oil mech would also be an issue. Wondering if something might have jammed in the bar sprocket as well. Cheers!

 

[Firewood Bandit]

Sounds like the brake was on....though you mention a couple of times it was off.
Could you explain how you know it was off?
Now to back up a bit,is this your first saw?If it is you should try and find someone that does a lot of work with a chainsaw and have them watch what you were doing,and then have them give you some lessons about maintaining and using a saw.
If you bought the saw from a reputable Stihl dealer,it would have been ready to use with no defects.
I still believe the answer is in the chain brake,and how you determine on whether it is on and off.
Thomas

I agree.

Probable causes in descending order.

Chain brake on, (could have accidently been applied by hitting with forearm)
While bucking log, cut closed and operator continued to throttle the saw while chain is stalled.
Chain tight and lack of bar oil getting to chain/bar.

Excessive heat on the plastic clamshell saws is real bad depending on how hot it got.