New Cummins owner here 2000 miles so far, I returned from a camping trip this afternoon and noticed a drop of oil on the street, so I slid under the truck and found looked to be oil that had dripped out of a black tube that appears to connect with the engine block, but can't see it real well.

The black metal tube comes down just above the front diff on the drivers side. There was some oil that had dripped down along the diff, and a little bit behind the oil pan, a real small amount. I know it's not the drain for the fuel filter.

Does anyone know what this tube is and do I have a potential problem?

Thanks

 

Sounds like you are looking at the oil breather tube and a drip or two would be normal on an engine that hasn't broken in yet as there is slightly more blowby past piston rings than on an engine that is broken in causing some oil to be displaced out the breather tube as the excess vapour build-up exits from the tube. Wouldn't worry at this time.

 

Make sure your oil level is good (most likely did that by now). A bad injector can fill the crankcase w/fuel & overflow out the breather tube.