What I have observed is when cold there is no leakage of oil. but once it gets into the operating temperature the breather (?) hose from the top of the valve cover will start to drip oil. Before this it seems to have what seems to be exhaust gas blowing through it. I also notice that the oil fill area seems to start leaking also. This is a clamped on hose tubing going up to a cap for oil addition. Upon shut off I can hear what sounds to be oil draining back down into the block. Could the valve cover fill up with undrained oil after running awhile and start coming out the top openings? The engine runs fine without black exhaust and has good power. However the oil leak amounts to enough to drain the engine in just a couple of hours runtime. Any thoughts, suggestions are welcome.
blowby
That does not tell me anything. Talking to a neighbor he suggested that perhaps the return oil holes through the heads are plugged with crap. That may be since the last person to own the dozer did not do routine maintenance like greasing it. Though it had new oil in in when I got it from the dealer who knows if the previous owner ever changed the oil. Might try a engine oil flush before pulling the valve cover. My neighbor said a lot of old engines will be gunked up from oil sludge. I can't imagine since I religiously change oil and filters on all engines.
After pulling the rubber boot on the blowby tube I found a metal cup that had a wire mesh in it. It was totally filled with oil which indicates it was plugged and not allowing the oil to drain back. I rinsed it with gasoline and blowed it down with compressed air. Upon reassembly and test running it took a long time to get to where any oil started dripping, about 15 mins. I tried differing idle speeds and it seemed a constant 1 drop every 2 -3 seconds, much better than previous leakage rate which was almost a constant stream. No doubt there is Blowby but it seems less leakage rate and the engine stayed cooler (outside temp is 95F). I need to refill the oil and run it a long time and watch for leakage. I have some new oil filters coming and I think I will change them out. I also think I will get a better grade of oil for the machine.