John deere 2020 hydraulic fluid into oil

[frankfia1775]

My dad has a jd 2020 we used it for a few years but never used the pto last year after brushhogging we realized it was low on hydraulic fluid and smoking out the blowby tube so we parked it went to eat checked oil and it was obvious that the hydraulic was in the crankcase. We rebuild the hydraulic pump ran it and did the same thing. So he bought a kit to bypass the hydraulic pump on the crankcase. He used it this spring for his garden no issues but this past weekend he was brush hogging again and when he was done it had the same issue hydraulic fluid into the crankcase from my understanding unless it's the Transmission the kit should have kept hydraulic fluid away from the crankcase and no possible way for them to mix what am I missing

 

[Tx Jim]

Welcome to this forum
If power steering pump mounted on RH front of engine is disconnected from hyd system I can visualize no way for hyd oil to access engine crankcase. Are you sure diesel fuel in engine crankcase isn't the problem?