Tractor Repair: ford 4000 leak, coolant temperature, cold weather

Question
I have a ford 4000 70's that just started leaking a sticky black fluid from exhaust and running down the motor.It is never been a problem until all of a sudden.It smells like there may be diesel mixed in. Any suggestions on how to troubleshoot problem? Thank you in advance.

Answer
  Hello,

  Sticky black stuff running down from the exhaust is unburned fuel because the engine is not running efficiently enough to completely burn all the fuel. Some people think it's oil, but it's not. This can be caused by the engine running too cold and not getting to operating temperature, from excessive idling in cold weather, thermostat stuck open, thermostat removed, low compression from worn rings, cylinders, valves, bad injectors, etc.  Check the coolant temperature, if it's running up to operating temperature, do a compression test to see if the engine needs internal repairs.  If the compression is good, have the injectors tested or replace them.

                   Arnie