Engine slobbering, oil and residue coming out of stack

A dark and heavy residue emitted around exhaust manifold gaskets on diesel engines. The operator can help eliminate the residue by avoiding unnecessary engine idling. "Diesel slobber" or "slobber" consists of diesel fuel and/or crankcase oil which has passed through the combustion chamber and did not burn. These are the "heavies" that did not burn because cylinders temperature are too low to promote complete burning.
The lower temperature occurs at:

• Start up while engine temperature increases.
• Engine is idled for a prolonged period.

Small amounts of crankcase oil can find their way past the piston rings and valve guides in a new engine or in a "cold" engine while idling. The unburned crankcase oil mixes with the unburned fuel to create the "slobber". In addition to the "slobber" you can see, there is an unseen amount of unburned fuel washing down the cylinder walls. This unburned fuel:

• Forms gummy deposits on valves, pistons and piston rings.
• Dilutes crankcase oil.
• Accumulates sludge throughout exhaust system.

664J Loader with a 6068 Hard to Start and then Dies!

What could be happening is your charge pump is losing prime. The way you test this if you don't have a laptop that talks to John Deere Equipment have someone crack one of the fuel lines leaving the injection pump. Have them watch it to see when it stops pumping. Next crack the line going into the injection pump if it stops pumping then it is your charge pump. If it didn't stop pumping then it is your Injection pump.