The D1402 in my Mustang seems to like to puke oil out the breather hose after things warm up (20-30 min) and the oil level goes down quite a bit (1-2 quarts??) in maybe 3-4 hours of operation. A bit (not much) oil vapor or "smoke" also comes out the end of the hose. The engine seems to be in fair to good shape, matter of fact, it was 14 Deg. F here today and it started up fairly well with no block heater. Makes me think it can't be TOO wore out?? I'm using synthetic Rotella 10-30 oil. It's not like it's really blowing a lot of air out the end of the hose. And it won't do it cold. Anybody else seen this problem with a Kubota 4 cylinder? Almost seems to me like the oil separator/baffle in the valve cover is a poor design, maybe OK for a new engine, but then when even slight blow-by begins, it can't deal with oil carry over. I'm thinking I need to take off the valve cover and make sure everything's intact that's suppose to be in there (no idea what) and if thats all OK, I think my next step is to modify the design a bit. Maybe a larger hose, or a catch can with some sort of drain back hose so the oil can return to the engine?? Maybe a baffle plate under the valve cover? Thanks for any info or ideas....
When it's blowing out of the vent hose take the oil filler cap off, if it's blowing out there with enough force to lift the filler cap off of the opening in the valve cover you need an engine. If it has ever been started with ether the damage has already been done.
I checked the oil fill cap as you wrote... There is ZERO pressure when the cap is just set on the cover, no lifting at low or high engine speeds. No vapor or 'air' coming out the fill hole either...