My 026 has a problem with chain loosening. Within minutes of cutting it is sagging, to the point that it fell off once. This sounds weird but I found a bolt (looks like maybe a 6mmx25mm or similar in size) hanging out of the bottom of the saw, in the gap on the clutch side. Also, that gap narrows significantly toward the bar and widens toward the handle. The Stihl parts diagrams are not very clear so I haven’t been able to identify where this bolt is supposed to be. Any thoughts?
Stihl 026 chain loosening
- Thread starter natej3
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- 026 chain loosening loose bolt
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Any pics??
Pics help get the best results but it is a challenge for me to post a pic
broken chain tensioner parts
Worn sprocket.
Screw may be the brake spring cover screw.
Only a guessing game without picts or the saw in ones hands, plenty of screws that either came out of the saw or was left loose in there by someone else that worked on it.
It's the chain tensioner. The bar was mounted to the saw without the tang on the tensioner being fitted into the proper hole on the bar and then the bar nuts tightened down jamming the tensioner against the bar and not allowing the bar to fit tight against the saw body. In this position, the bar and side cover is skewed out and bar nuts will not hold the bar from slipping, hence loose chain. The screw that runs the tensioner gets bent but usually doesn't fall out. Seen it often.
When that happens is the fix as simple as replacing the tensioner and it’s screw? I could see that happening as my son had borrowed the saw before this happened (kids these days). If so, I would still like to know where this bolt goes. Here are a couple of pics. Notice the loose bolt hanging out of the gap. That really makes my saw look worn, but it still runs great.
Take the clutch off, and the cover above it, make sure its not a case half screw that has come out, not sure how it could, but you never know.
And where is the front AV rubber ? behind the lower part of the felling spike ?
If your saw is shedding spare parts, you need to know where they are coming from.
And where is the front AV rubber ? behind the lower part of the felling spike ?
If your saw is shedding spare parts, you need to know where they are coming from.
If the bolt is really 6mm, I doubt it's from your saw. I'm pretty sure there are no M6 bolts in the 026.
I assume you took the inner bar plate off for your picture so we could see the tensioner which looks to be in good shape.
The right front AV buffer is missing which likely has something to do with the "gap narrows significantly toward the bar and widens toward the handle"
I assume you took the inner bar plate off for your picture so we could see the tensioner which looks to be in good shape.
The right front AV buffer is missing which likely has something to do with the "gap narrows significantly toward the bar and widens toward the handle"
I think this is what I was thinking of saying but I was to slow in my thinking so I think I will say "DITTO"
Just grazing through the IPL there is a few M5 bolts used. If that bolt goes to your saw id guess it was holding the halves together. The coil takes a similar bolt also. Id pull the clutch and check.
Also, have you just put a newer, or different chain on, but not changed the drive sprocket ? that can give a chain that loosens as its used, as it wears into the drive sprocket.
Also you are missing the chain catcher that screws into the plug that goes into the before mentioned missing annular rubber/buffer.
Also you are missing the chain catcher that screws into the plug that goes into the before mentioned missing annular rubber/buffer.
You need to a bit more disassembly there Nate to find out where that screw came from and you need to find some small parts to get the saw back together properly first, then the chain loosening will likely be an easy fix. Chain loosening is mostly a drive sprocket,( rim drive ) in this case or a worn bar end sprocket , a new chain will stretch for the first couple hours of operation and then slow up after break in.
You guys don’t miss much. I removed that front rubber buffer and it’s associated hardware in an effort to disassemble the saw. I had not yet taken the clutch off—that is probably where I’ll find the missing bolt (I hope). It might well be a 5mm. I assumed 6 because that’s what most of the other 2stroke equipment I have use. I was a bit suspicious of the sprocket because it seems to have some excessive slack (sided-to-side movement of about 1/8 of an inch). Thanks
The sprocket is designed to have some side to side movement but if its kind of jiggling around then its the wrong center size for the 026. The 026 takes the mini spline rim sprocket and I have seen a few times someone has used the next size up one making the sprocket too loose on the drive. Pop the E clip off and take a look.
My theory about damaged chain tensioner is shot to hell. Nothing wrong with it. Like they say, a little more disassembly should solve the mystery.
Natej3, do you lift on the end of your bar as you adjust the chain and tighten the cover bolts? If not, this may be why your chain gets loose.
NickC
ArboristSite Member
If the gap between crankcase and handle chassis is uneven there (before disassembly) the front av could be soft allowing the crankcase to slip back and forth, the chain oil makes them spongy in time.
A case screw may be unlikely to end up there, whip the top cover off and look down through the cylinder fins first as it's easy to check if all four screws are in place. Has the cylinder been off? Someone may have 'lost' a screw and it got caught up in the casting webs, eventually shaking out.
It looks like a Stihl screw by the anti shake serrations under the head.
A case screw may be unlikely to end up there, whip the top cover off and look down through the cylinder fins first as it's easy to check if all four screws are in place. Has the cylinder been off? Someone may have 'lost' a screw and it got caught up in the casting webs, eventually shaking out.
It looks like a Stihl screw by the anti shake serrations under the head.
