Stihl 341 oil pump blocked with horrible gunk.

[Ged]

First post here.

I'm the proud owner of a very used Stihl 341.

Had it for about two years, cut about three or four tonnes of wood with it.  It's a fantastic tool, well on top of everything I think I'll ever need to do.

When I got it, the oil pump didn't work.  I found the description of stripping it down to get at the pump a bit intimidating so I've been using an oil can every minute or two to keep the chain wet.  Yes it was tedious.

Finally with information from this and a couple of other forums - for which I am most grateful - I plucked up the courage to fill the cyinder with oil to lock the crankshaft so I could take off the clutch to get at the oil pump.  It was all surprisingly easier than I expected, and if I'd known then what I know now I'd have done it years ago.

Anyway the oil line was clear enough but when I removed the oil pump itself I found that the oilways in the pump were totally blocked with a grey gunk which had a consistency something like half-set epoxy resin.

What on Earth would cause that?

Is there something I can do to prevent a recurrence?

There's no way that I can see to poke anything right through the oilways to clean them because there are right-angles in them.  So I soaked the whole pump in a jar of Aspen 4 for a few days, and then cleared it out as best I could with bits of bent wire and (because I was desperate) an interdental toothbrush and compressed air from a bicycle pump.  It all worked a lot better than I thought it would and to my great relief, now that it's all back together, the oil pump pumps oil.

[NewYankeeSawmill]

Welcome!
Lots of good info here. Try searching for previous posts - though admittedly I do better turning google loose on the site than I do the internal search feature.

[doc henderson]

If you bought it used, it may have set a while.  Not uncommon when folks sell stuff.  Mine failed with lots of oil and saw dust got in there.  just replaced the oil pump.  there are bits made of nylon so it will crack if in a bind.  glad you got it working.  some people try all kinds of oil in there so who knows.  could of had moisture in there, or vegi oil that went rancid.