Sprayer pump problem

[JPB]

Hi,
I have an eastern European sprayer, recently it has started leaking oil out of the filler cap on the pump. What would make it do this? It's obviously under some pressure. It's been like it a while to be fair and it's seems to have been working ok so I've not touched it. About 100 acres ago the pump was running noisy and i checked oil and there was little in so I filled it up. And ever since then it's never needed any more and still looks fairly clean, slightly grey but I've never drained it out completely so I'm guessing there's a bit of gunge in there! Any advice on why it's blowing oil out would be gratefully received.

 

[milkloss]

Likely a diaphragm gone I suspect. @SimpersTradeCounter be your man in the know on here.

 

[snipe]

Same as what milkloss has said above.

 

[SimpersTradeCounter]

Thanks you two
@Joshie what state is the oil in? is it milky?
Could it have been overfilled with oil?
It could be that a diaphragm has spilt and allowed water/chem the oil side of the diaphragm and caused the crnk case pressure to rise and therefore spit oil out of the cap.
All guesstimates but give you somewhere to start looking