D2350 problems

[wayne2342]

My neighbor has a D2350 that seems to produce black smoak too much. Also it appears to be running off 3 of the 4 cylinders plus when the tractor idles for very long the oil level appears to rise slightly. When the tractor has run for some time, the motor will surge which may be the 4th cylinder firing for a minute. All of these issues may be related, eg smoking due to unburned fuel, fuel leaking into the crankcase through dead cylinder. The injector for the dead cylinder was pulled, cleaned and tested at a local shop and is has a good spray pattern. Anybody have any advice on what could be causing these problems?

[lens12]

Broken or stock rings.