HELP.....STIHL 028av chain sprocket

[ZeroJunk]

They made a million of these. I don't think there is any difference between the supers except the have a 2MM larger piston and cylinder. They will work fine with the stock clutch. I have one torn down on the bench now that needs a piston and I think I will just put it back stock. I have bought the oil pump drive gears on eBay. If it's like most Stihl parts you can probably buy a whole junk saw for what they would want for the clutch cover.

 

[crankster69]

Nothing like posting on an old thread, eh? Recently picked up an 028 Wood Boss. Starts and runs just fine. But when I tried cutting wood the chain went TIGHT and stopped turning. I pulled off the cover and looked at the sprocket. How would you grade this sucker?

And what to make of the black burned appearance on the sprocket?

 

[Clyde85]

Friction.

 

[ZeroJunk]

That sprocket is about as worn out as I have ever seen. It is possible that the chain is binding in it.
Replace the sprocket and clean the junk out from under it. See what happens.

 

[HarleyT]

Throw out the chain that was on it as well!!
Very important!!

 

[crankster69]

Friction.

Hello! Can you explain "friction"? Do you mean the sprocket is so worn that the chain tightens?

Thanks

 

[HarleyT]

As a sprocket is worn that badly, the chain/sprocket geometry is way off, and it causes bad damage to the bottom end of the chain, and it peens out the metal, making it wider. Put up a pic of your chain.

 

[HarleyT]

Here is a new chain and sprocket. Now, do the same thing with yours, but your chain will ride in the notch/slot, and you will see what is going on.

 

[crankster69]

Here is a new chain and sprocket. Now, do the same thing with yours, but your chain will ride in the notch/slot, and you will see what is going on.
View attachment 922002

I would share a pic but I'm at a remote lake location (top secret) in the wilderness. I'll share later! Thank you.

 

[crankster69]

Finally got back from vacay and pulled the old sprocket off. I could not find a part number on the sprocket anywhere. I even washed it hoping to find something. No luck.

 

[crankster69]

How do I know for certain what sprocket to buy? I cannot find the chainsaw serial number either.

 

[crankster69]

Check out this little fella. Looks like he's had a hard life. Suppose I should replace it while I have things pulled apart.

 

[crankster69]

Just some pics as I pulled it apart. Anything look noteworthy?The plastic plate/cover is a little beat up. Maybe should be replaced? Would you?

 

[Maintenance supervisor]

View attachment 923152
View attachment 923153
How do I know for certain what sprocket to buy? I cannot find the chainsaw serial number either.

You can go to "Oregon product finder" and it'll give you the correct part number.

 

[HarleyT]

 

[crankster69]

View attachment 923168

Excellent. Thank you.

 

[crankster69]

View attachment 923168

the washer part #37 was not on my sprocket. Only the part #31. Thoughts why that would be missing?

 

[atpchas]

the washer part #37 was not on my sprocket. Only the part #31. Thoughts why that would be missing?

#37 is an e-clip, not a washer. In your picture in post #30, part #30 should be resting against the nylon oil pump gear and part #37 should hold it in place, riding in the narrow groove on the sprocket gear. The washer (#32) goes on next and is held in place by e-clip #37.

BTW, your plastic cover looks to be in very good shape for a saw this old, at least from the angles visible in your pictures. In particular, I see no sign of heat damage from the clutch drum getting too hot.

 

[Woodslasher]

Check out this little fella. Looks like he's had a hard life. Suppose I should replace it while I have things pulled apart.

That looks fine, on most of the saws I've gotten those will be chewed off flush with the case.

 

[Wood Doctor]

That looks fine, on most of the saws I've gotten those will be chewed off flush with the case.

I've actually seen a case where the chain cut right through the sprocket and the bearing and was working on the crank shaft. Customer said, "Shucks, it just won't turn or tighten anymore. We had a big job to finish."

To which I replied, "You almost finished off the saw instead."