Yanmar 4JH2...80 HP

[straitscrew]

Further to earlier post.....the rebuilt engine suffered exactly the same problem as original, namely loss of oil.
It seems early version circa 1997-1999 were fitted with an injector pump that was lubricated with engine lube oil.
This oil feed line, if fitted can be seen running from engine block behind and slightly above oil filter to the injector pump.
The seal that separates the lubricating oil from the low pressure fuel within the injector pump can and did fail and all engine lube oil is then transferred to fuel system and typically returned to fuel tank.
My engine had about 14,000 hrs. Once this seal goes it only takes 1- 2 hrs for all engine lube oil to vanish and unless you are monitoring oil pressure or have LOUD alarms there is little warning. Red warning lights in daylight are useless.
Yanmar were obviously aware as later models have injector pumps lubricated by the fuel passing through them .....as I now have.
If you have this older model i suggest you check what type of injector pump and if lots of hrs get the seal replaced