034 av leaking

[Maxd]

Here I have a 034av that seems to be leaking somewhat does any body have any ideas on why it may be leaking so much?

[pleasant]

Chain oil or fuel leak- can't tell as it's soaked into the cardboard. I would guess chain oil leak given the pic locations, but you never know.

[Maxd]

Yes this is a oil leak but any ideas on where it is coming from why and how🤔 

[pleasant]

Crack in the mangesium casing, failed o-ring on the filler cap, gasket failure between casing halves, tank vent valve failure, oil hose perished or chafed

 

 

Edited December 23, 2022 by pleasant

[Maxd]

The oil hose is probs perished as it it vv hard feels like plastic...

Any ideas on how to check for the other issues 

[pleasant]

Personally I would start with the easiest and most likely cause which you have already alluded to, and fit a new hose, then check everything else after.

Edited December 23, 2022 by pleasant

[spudulike]

Those push in breathers can go open and start leaking. Just take the filler cap off when the tank is empty, push a bit of petrol pipe against the breather hole and suck and blow and if it flows both ways, punch it in to the tank, shake it out and push in another one.

If the oil tank only leaks when full then it may be the breather. If it leaks right down to the bottom then a leaking oil pump, crack, oil pump seal etc can be suspected.

[pleasant]

...agree those breathers had a it of a reputation back in the day. Certainly worth checking whilst changing that hardened pipe he says it has.

[Still Stihl]

I had the same recently on two of my saws. Replaced the rubber teat type breather on small saw and knocked out the metal one on 390 blew it out with compressor and replaced it shortly afterwards. Leaks sorted.