Stihl 041 FarmBoss leaking bar lube into cylinder

[andy b.]

i went to use my dad's old 041 FarmBoss (i think he bought it in 1975) and the pull start wouldn't pull. i pulled the plug just to see if that may have something to do with it, and the cylinder was full of bar lube. i emptied the cylinder and pulled on the pull start a few times and all was loose. i then filled up the bar lube reservoir, and the lube basically would run right out the spark plug hole.

i am guessing this is not a good sign, since i do not believe there should be any connection between the lube tank and engine cylinder. is there a gasket that may have went, or is it more likely the case halves have cracked? if it's a gasket i'll dig into it and see if the saw can be repaired, if not i guess it is time to list it on ebay as parts. are any gaskets even available for these old saws?

andy b.

[Steve Shearman]

The only way it can get into the cylinder is though the bar lube oil pump you will have to check it out

[andy b.]

Steve,

do you know of any links for exploded diagrams of the 041 or a shop manual? or is it pretty self-explanatory once i get into it? i have never had a chainsaw engine apart, but i have had just about every other type of engine apart.

also, at one point my dad was not really all there mentally. he ran the saw a few times with no bar lube (once i found out i put the saw away so he wouldn't use it any more). could this have ruined the pump, or is it lubed by the engine oil-fuel mixture?

andy b.

[andy b.]

I just wanted to give an update. I have too many projects at present and the local Stihl service guy seems to know what he is doing, and he works cheap.
I dropped the saw off with him a month or so ago and asked him to see what he could do, and if it looked like it was going to turn into a $200 project, to call me. Well he fiddled with it in between doing real work, and it ended up being the o-ring between the lube pump and the rod/cam that operates the pump, and a seal inside the pump itself. Stihl still stocks those parts and he called today and said it is back together and running fine. I'm going to pick it up Monday and put it back to work.

Oh, and the entire bill only came to $38. I can't complain about that.

andy b.

[Andrew Mackey]

Common occurance when the saw is run with the oiler dry. Thank goodness, an easy fix for you. More often than not, the plastic cam gets wiped out too.
Andrew

[andy b.]

Yeah, that is pretty much what happened (oiler ran dry). My dad was using it a few times and I checked it and there was no oil in it. After that I put it away so he couldn't get at it.

I was looking at the saw a week or so ago and it looks like the oil pump is just held in with a circlip. If I had a decent parts diagram I probably would have pulled it out myself. Like I said though, the repair was pretty cheap considering I didn't have to do anything except drive a mile to drop it off and then go back to pick it up.

andy b.

[John Marrais]

That oil-pump leak is a common problem with 041s. Many did it when only a year old. Ten mintue job to fix. The end of the oil pump has a tapped hole that you put put a screw into. That screw acts as a handle, so once the circlip is removed, you just pull the pump out. Stick the new rubber seal on, and slide it back it. That's all there is too it.