So I've recently purchased a 2003 cummins....had it about 6 or 7 months. I've noticed when I go to start it in the morning for work, MOST of the time, not all the time, it starts right up then either dies or stumbles and catches itself. Been like this for months...had time to finally check it out and there is a very small leak coming from the HEAD. Right next to the injector line number 4. I've changed the tube, o ring, and injector line with cummins parts. Same thing. Small amount of diesel coming from the crack of the head. Then works it's way to the back of the motor and down and will start dripping after about 20 mins of idle. I'm kinda stumped right now....and advice?! Thanks guys....

 

A crack in the head you say?

If you're sure about that... there's really only one fix for it. And it isn't cheap.

 

The seam of the head...it follows it down and then down the side of the motor. Like it's coming from inside somwhere?

 

 

It seems to be weeping right above the black line I drew in the picture

 

If I might suggest, with the engine running slip a piece of paper or something between the injector and the seam, and see where it is coming from. DO NOT USE YOUR FINGERS. You may have a small crack in the injector, or a seal that is no good, even though you say you replaced them.

 

Seems I was way wrong.....seems like the return line goingto the back of the head was loose! Got a 19m wrench and reached back there and sinched it up. Pressure washed engine bay again and everything seems dry!

 

Glad to here that. Something so simple, yet so aggravating. Keep a eye on it.