My 81 TD is having trouble shutting off. Yesterday I got involved with the vacuum system, replacing the vacuum switch on the ignition barrel, as well as replacing come of the connections that seemed not to seal as well as they aught. A red light went off in my mind when I found that there is oil in the vacuum line coming from the shut-off actuator. I tested the actuator on its own by connecting it directly to the main vacuum line (as described in the manual), and found that it still seems to work fine. I figure that the oil in the line is causing resistance that is not allowing it to shut off easily. My questions to the forum are:
1. How can there be oil coming from the actuator? (It is definitely coming from the actuator.)
2. Can this be fixed be replacing the actuator, or is this indicative of other/bigger problems? All other vacuum related systems seem to be in good working order.

 

You have a hole in the Diaphragm of your Vacuum Shutoff Valve on the upper rear of your Fuel Injection Pump. The Vacuum is sucking some Oil from out of the Fuel Injection Pump through the hole in the Diaphragm.
If you change the Vacuum Shutoff Valve yourself pay close attention to how it comes off and be sure the L-shaped tab goes back where it is supposed to go.
If you do not get it in correctly your Engine can run away. Before starting the Engine after the job be sure you have some way of blocking of the Air Inlet (the faste way to shut it off) or some way to cut off the Fuel incase it does try to runaway.
Someone on another forum just did this job and has some handy tips.
Install Vacuum Shutoff Valve

 

Thanks for the advice. I figured a hole in the diaphragm was the likely culprit, but I didn't know if oil leaking into the lines was a sign of something more serious in the IP. Based on your advise I looked up a tutorial on diesel giant, which was very helpful. I now see what you mean about the engine being forced to full throttle, and how to prevent that. I ordered the parts, and can't wait to get dirty on it. Thanks again for the tip.