Sullivan Diesel Air Compressor Not Making Air

Questions & AnswersCategory: Air Compresser TroubleshootingSullivan Diesel Air Compressor Not Making Air
James asked 5 months ago

I have a Sullivan Palatek D185Q11JD that is not making any air. The throttle actuator has no air moving it so the throttle shoots up to max I have pulled the hose off of the inlet valve and the valve sits at closed at full throttle. I am thinking the coupler between the engine and air end is broken.

Is there anything that would stop the air end from producing air at full speed?

1 Answers
Cas Staff answered 5 months ago

Hi James,

Thanks for the question.

Normal startup cycle for a diesel compressor like this is like this:

  1. engine stopped – no air pressure. Speed actuator is at full speed. Inlet valve is fully open.
  2. Engine starting up
  3. Engine running – goes to full speed (speed actuator was at full speed to start with). Since inlet valve is open, pressure starts to built.
  4. Presure builts up – at this ‘start up’ stage, usually the outlet pressure is directly connected to the control pressure (until you press that ‘load’ button).
  5. When (control) pressure builts up more, the engine speed actuator will reduce engine speed, and inlet valve will start to close.
  6. Pressure reaches normal working (setpoint) pressure – engine speed is now idle and inlet valve fully closed
  7. Compressor runs in unload mode.

All those takes just a few seconds maximum.

So normally, you would hear the engine start, rev up, pressure will built up quickly and the engine will go to idle.

Now back to your compressor…

The one thing that is not right is that your inlet valve is closed, while the engine runs at full throttle. With a closed inlet valve, the compressor won’t produce any air.

*most* of the time, inlet valves on these portable diesel machines are ‘normally open’ – that is, they are open when no control pressure is applied to them.

Not sure about this particular machine.. but I believe it’s ‘normally open’.

So please investigate that.

About the coupler.. yes of course that could be the problem as well and it would result in the same problem.

Hope this helps 🙂

Good luck!




Your Answer