Monday, April 12, 2010

Unscheduled Stoppages

"Unscheduled stoppages": That's what the Previous Owner termed them... When the engine stops, not because you command it to do so, but of its own volition (or perhaps lack of volition).

Diesel engines are remarkably reliable. Because there is no electrical system involved in the operation of the engine, it is purely a machine. It will run until:
  • Something breaks
  • It runs out of fuel
In fact, that's how you stop a diesel engine - you cut off its fuel. Therefore, if your engine stops on its own, unless broken greasy parts have suddenly appeared on the cabin sole, you should start your search for the problem with the fuel supply.

Eolian's original fuel system looked something like this (starting at the tanks):
  1. Two steel canister filters, either one of which (or both) could be valved in line
  2. A large Racor filter
  3. The lift pump (on the engine)
  4. The final polishing filter (on the engine)
  5. The injection pump (on the engine)
  6. Enough (unlabeled) valves to fit out a nuclear reactor

Not surprisingly, our very first unscheduled stoppage happened on our very first voyage. It was caused by operator error - I had some of the valves incorrectly set up, directing the fuel thru an auxiliary electric fuel pump (not mentioned above, since it wasn't supposed to be in the flow path), whose small internal passages blocked off with gunk in the unfiltered fuel.

We were to suffer many more, some in pretty precarious situations. Like the time we were just making the turn into the marina after a day of sailing. We were in the entrance to the Ship Canal. The locks had just opened and there was a host of boats heading out, bearing down on us. And we were drifting toward the rock-studded shoal on the south side of the Ship Canal entrance. We were fortunate in that we had just furled the sails - we just unfurled them, and Jane began tacking us back and forth across Puget Sound, while my son Adam and I chased bubbles thru the fuel system.

Eventually we resolved the problem, by taking these actions:
  • Remove the steel canister filters. As it turned out, they were completely empty - there were no filter elements in them at all
  • Install a second Racor 90 gallon/hr filter in parallel with the first. This is way more filter than our flow rate requires, but it's large size provides a large filtration area.
  • Redo the fuel plumbing, eliminating a pile of valves
  • Create a plumbing/valving diagram, and post it on the bottom of the floorboard, where it will be at eye level when operating any of the fuel valving
  • Label the valves
  • Repair the fuel gauge sending units in the fuel tanks
  • Install a second Racor vacuum gauge in the panel adjacent to the companionway, where it is easily viewable.
We haven't had an unscheduled stoppage since these have been completed.

That loud pounding you are hearing is me, knocking on every piece of wood I can find...

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