While I've seen this many times, I've often not been unable to capture it, since the moment I take out the camera the smoking stops. This time I got lucky however. I was shooting brand new ES44AC, CP 8761 who is right in front of him, when all of a sudden he starts smoking. If you look really carefully you can see an employee running inside the nose, probably to shut her off. The real sad thing is that this engine is only 3 years old. Yet its smoking like crazy, this is relatively new stuff, even if it is from the pre-GEVO era.
You're probably wondering what that weird thing at the bottom is, the truth is I don't know. Since depo acces is quite difficult, this photo was shot standing on a mud-pile in front of some contractor's parked car, through a hole in the fence and just above an empty IMS.
Note that he is covered in his own shadow created by the smoke.