# Stihl FS81 brush cutter



## woodbutcher (Apr 25, 2005)

I took the engine apart and removed the cylinder from the crankcase. I found flakes of steel in the crankcase that would lock up the crankshaft as it turned. They seem to be coming from the bearing that is on top when assembled. I am trying to fish out all the flakes, but a couple of them are too big to slide out in the space allowed. What is the proper procedure for splitting the crankcase to free the crankshaft?
Butch


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## rotti1968 (Apr 26, 2009)

stihl has a special tool to seperate the crank case and the same tool is used to draw the crankcase back together.You may be able with a propane torch to heat around the bearing areas to expand the housing and with a press seperate them also and put them back together the same way. You need to make sure when putting back together that crank moves freely,it may need a light tap with a plastic tip hammer on the crank end to move it one way or the other to get it to move freely. I may be able to get you a pic of the stihl tool ill have to check.

The flakes of metel your refering to may also be the lining of the cylinder walls take a very close look at that area.Flakeing of the chrome is normally caused by water ingestion.


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## woodbutcher (Apr 25, 2005)

Thanks for the info. It sounds like it might be more work than I'll want to invest. I looked at the cylinder and the flakes don't seem to be from the cylinder wall. Is there a steel bearing or seal housing inside the crankcase on the end of the crankshaft that could be the source of the flakes?
Butch


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## woodbutcher (Apr 25, 2005)

Okay, I think I found the source of the flakes. The bearing on top of the crank has 8 or 10 ball bearings, and there was a retainer to keep them in place. For some reason, that retainer came off the bearing and got shredded between the crank and the side of the crankcase.
Butch


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## rotti1968 (Apr 26, 2009)

I have to look tomorrow,Im not sure if Stihl still has a short block for that unit . I would not if it was me put a lot of time,effort or money into an engine that has damage like you have found. you more then likely would need to replace the damaged side of the crank case,the crank shaft,bearings,seals etc.. Ill try to post a rough list cost tomorrow . I have the parts breakdowns here at home but no prices ....


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## woodbutcher (Apr 25, 2005)

I sure appreciate all you're doing. As you said, it's probably not going to be practical to spend a lot on getting this machine back in shape. It would be interesting to see what a short block would cost.
Thanks.
Butch


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## rotti1968 (Apr 26, 2009)

No short block offered that I can see.... Just the crank case,crank shaft,seals,wrist pin bearing,crank bearsings list for 305.40. We sell the fs 90 r (loop handle) for $290.95. so you can see its not worth putting any time or money into the one you have .


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## woodbutcher (Apr 25, 2005)

Yep. You're right. Thanks again for your help with this.
Butch


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