Hey everyone. I don't post much or read much here on the cummins side, I stay on the 2nd gen threads because that's the truck of mine that needs the most attention. But I have a 05 Cummins 3500. It has been showing signs of oil spots under it in the garage. I climbed under there to have a look and found that the tube that comes from the valve cover and hangs just behind the front axle is very cruddy and is definitely my source of oil spots. This is the crank case breather/valve? Why would that being leaking oil? the spots are probably 4 inches in diameter or so. I didn't take the cover off the valve cover to inspect the upper end of it, I didn't have time. Thanks guys.

 

IIRC you have an empty plastic box that is supposed to separate the oil and dump it into the valve cover, at the top end of that hose. Sounds like you're getting a bit of blow by.

 

Thanks horatio for stepping up and offering some knowledge. Is this anything I need to be alarmed about and addressed right away?

 

I wouldn't be too concerned with it, unless it gets bad. Doing a bit of research on it shows that there are a few causes, worn/scored cylinders causing cylinder pressure to enter the crankcase being the expensive one to fix. Apparently the vacuum pump exhausts into the crankcase and if you've got a leak, it can cause blow-by too.

Some is relatively normal.