# Chain wont stay tight on Stihl 021



## Bakemono (May 17, 2008)

Ive got a Stihl 021 that has been a great little saw. It starts right up, runs great, but Im having issues with the chain not staying tight.
You can tighten the chain correctly and tighten the nuts on the side cover as hard as you want and after 5-10 minutes of using the saw the chain is loose again.
The other day my brother and I took it apart and the tenioner looks OK, but perhaps the screw is worn and due to the vibration it just works itself loose over time.
Does this sound right? Thats really all that I think it can be. Ive tried various chains and even tried a different bar and Im getting the same results.
The 021 has been a good little saw to me. 8 years ago I traded a pizza oven for it and its never given me any trouble up to now. Its just annoying that you have to stop every 5-10 minutes and retighten the chain. I know that the chain is supposed to slacken somewhat after you use the saw for a while just due to the chain heating up a little, but this is to the point where the chain will almost come off of the bar.
Im honestly to the point where Im about ready to just go out and buy a different chainsaw, but if its something simple and inexpensive like the tensioner being bad, Id hate to go out and spend $300 on a new saw when I could fix my old one for $20.


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## Bermie (May 17, 2008)

Slap me if I'm telling you how to suck eggs...

Are you holding the bar nose up when you tighten the chain and side nuts?
If you don't, the chain will slacken off regardless how tight you do the side nuts.
Double, triple check you're getting the tensioner post into the hole in the bar...

If you've had it for 8 years, its probably going to be the tensioner assembly, check it all out, is any of the plastic around the assembly worn or broken, how does the assembly itself look?
I can't think it would be too much $$ for a new assembly, but if the plastic seating area it worn, then there will be more to do...

My 021 is just a little older than yours, still going strong!!


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## Fish (May 17, 2008)

Your sprocket is likely worn out, and you need that, and a new chain.


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## Bakemono (May 17, 2008)

Bermie said:


> Slap me if I'm telling you how to suck eggs...
> 
> Are you holding the bar nose up when you tighten the chain and side nuts?
> If you don't, the chain will slacken off regardless how tight you do the side nuts.


Yup, Im making sure that I hold the bar up when I tighten the chain and the nuts.


> Double, triple check you're getting the tensioner post into the hole in the bar...


Trust me, its in there.



> If you've had it for 8 years, its probably going to be the tensioner assembly, check it all out, is any of the plastic around the assembly worn or broken, how does the assembly itself look?
> I can't think it would be too much $$ for a new assembly, but if the plastic seating area it worn, then there will be more to do...


The plastic that it sits in isnt worn, its fits in there snugly. I was looking at it today and I noticed that it doesnt take much force to turn the screw. I could hold the screw between my thumb and index finger and turn it pretty easily.



> My 021 is just a little older than yours, still going strong!!


The saw itself is 10-15 years old and it still runs great. It starts in 2-4 pulls and runs strong. Thats why I hate to go out and spend $200-$300 on another saw if its a simple fix. 
I'll try a new tensioner and see if that fixes it. Im not sure how to change the sprocket and Id bet that for what it would cost to have it fixed for me I could just go out and buy a new Echo CS-370, so I see little sense in investing the money to fix my 021 unless its a cheap fix.
Thanks for all the help.


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## scottr (May 17, 2008)

A new sprocket and chain will be very reasonable.


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## Bakemono (May 17, 2008)

Im not too worried about the cost of a new chain, that should be about $35. Even the cost of the sprocket shouldnt be too bad, but I dont know how to change it and the cost of having it changed for me is going to be the real killer.
Like I said, I could go out and buy a new Echo that is comparable to my old 021 for $200, so if its going to cost me more than $200 to fix my old saw, I might as well just go out and buy a new one.
No doubt I could sell my 021 on Ebay and get at least $100 for it.


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## ray benson (May 17, 2008)

Remove the E clip and the sprocket comes off.


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## Bakemono (May 17, 2008)

ray benson said:


> Remove the E clip and the sprocket comes off.


Ok, thanks!


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## Bakemono (May 17, 2008)

Just out of curiosity, why would the sprocket cause the chain to not stay tight?


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## cjcocn (May 17, 2008)

Bakemono said:


> Just out of curiosity, why would the sprocket cause the chain to not stay tight?



That's a good question!

I'll take my best uneducated guess here ....

With a new sprocket and chain, the drive links on the chain fit nice and snug into your sprocket. When your sprocket is worn, you can seemingly get it tight, but what it is really doing is snugging up against one side of the recesses in the sprocket. When you run your chain, your drive links maneuver themselves to the area of the sprocket that provides the least resistance, thereby allowing the chain to loosen.

Now one the guys that actually know can let us both know if I am correct.


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## Fish (May 17, 2008)

Wow, chain prices up there must be real high


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## Fish (May 17, 2008)

Sprocket should be $15.95 from a Stihl dealer, $12 from anyone else.
Good loop of Oregon or Carlton chain @ $15-$18, 3 minutes to replace.


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## ray benson (May 17, 2008)

Chains wear grooves in the sprocket teeth. The chain shifts in and out of the worn grooves when running and causes the chain tension to change.


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## Bakemono (May 17, 2008)

Would I be able to see these grooves on the sprocket?


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## Bakemono (May 17, 2008)

Fish said:


> Wow, chain prices up there must be real high


I could probably get an Oregon chain for about $20 at the local Farm and Fleet. I know that you pay a premium for anything that says, "Stihl" on it...
At least now I have an excuse to get rid of that stupid "safety chain" (low kickback) that came on my saw.


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## Fish (May 17, 2008)

here is a good sprocket, beside one with some wear, yours is likely notched
much worse.


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## Bakemono (May 18, 2008)

Hmmm, ok. I'll have to take a look at it sometime today. Thanks.


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## SSGJ (Feb 27, 2009)

*Chain won't stay tight on stihl 021*

You could have to do what I did and put studs in stead of the bolts. Then use a nut as a jamnut. Then I ground down the top and bottom so that the bar would slide over them taking the slop out of the bar and keeping the chain tight. Its worked for me for about 2 years now on my 021.


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## Raymond (Feb 27, 2009)

Fish said:


> Wow, chain prices up there must be real high


That's what I was thinkin'


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## WildnCrazyGuy (Feb 27, 2009)

Sound's like you know what you're doing, but I have to add... I've got an 021 also, and I experienced the same thing you described and it turned out my oiler was clogged not getting enough bar oil to the bar/chain causing it to heat up and expand, thus was loosing tension about the timeframe you stated. So, check to make sure you are getting plenty of bar oil and the chain is not running dry.


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## AT sawyer (Feb 27, 2009)

*Old 021?*

I'm jumping into this late here, but my ancient 021's original side plate was PLASTIC. It eventually wore out after repeated (years) torquing of the bar nuts. When I bought a replacement, the newer Stihl cover had metal grommets where simple holes in the plastic used to be (big improvement). Are you sure it's eight years old and not 18?


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## aldo (Jun 16, 2009)

Thanks for posting up some pics Fish. I spent $280Aus getting my 021 serviced and they gave it back to me with a sprocket that makes the one on the left look like a new one. I have since rung them and told them that I'm a bit peeved and they are looking into it for me. In Oz $280 is nearly half the price of the new equivalent.

Is there any way of finding out the age of the saw? Mine is one which has the tool free chain adjuster.

Thanks


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## Deadwood Kid (Jun 16, 2009)

my buddy was having this happen to him with a 61 husky. his chain tensioner was broken or something. fixed the problem with a $1 part. hope thats all you need x.x


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## rmh3481 (Jun 16, 2009)

Here is a bad one. You can see the teeth are worn away to nothing.


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## Fish (Jun 19, 2009)

Here is a common sight here in Ky...

Kind of sad, really.........


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## Rookie1 (Jun 19, 2009)

Why?


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## Fish (Jun 19, 2009)

Disclaimer: No dogs were actually harmed in the making of this photo.......

Why?

My mother asked that a lot.......


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## Rookie1 (Jun 19, 2009)

She has my utmost sympathy. Good to hear the dogs werent harmed. Why post it on this thread. Bucktoothed dogs have nothing to do with chain tension. Do they?


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## Raymond (Jun 19, 2009)

Rookie1 said:


> She has my utmost sympathy. Good to hear the dogs werent harmed. Why post it on this thread. Bucktoothed dogs have nothing to do with chain tension. Do they?


Why you gotta green machine for a 
avatar picture in a tree trimming site?


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## Rookie1 (Jun 19, 2009)

I like working on 031s with points ignitions. I always type that they are old skool. Another member gave it to me to use.


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## Raymond (Jun 19, 2009)

Rookie1 said:


> I like working on 031s with points ignitions. I always type that they are old skool. Another member gave it to me to use.


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## Fish (Jun 19, 2009)

Rookie1 said:


> Why?




Actually, you hit it right on the head there Rookie.

Why indeed????

If I had not brought this thread back up, another question of the same/type
would pop up again, and the cycle would start again, and some member would
convince the poster that his crank was bent.

I just injected a bit of humor, to get everyone to read it again, and not repost the same question, which I have responded to dozens of times here.

Or I just injected some humor, just because I like to, either way, same
results.....


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## Rookie1 (Jun 19, 2009)

Your the bomb Fishie.


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