Ask SAIL: Fuel Vent Spill Prevention
Q: Filling my diesel tank is a pain, since fuel coming out the vent is the only signal that it’s full. This is because my tank vent is several inches lower than the fill opening. Is there a reason for this seemingly poor
arrangement? Is there a preferred vent line remedy?
Dean Matcheck, Key West, FL
DON CASEY REPLIES
A vent fitting lower than the fill fitting is a common annoyance with, as you note, environmental implications. You have at least three options. The first is to abandon your current vent fitting and change your deck fitting to one that also attaches to the vent hose. This puts the vent at the same level as the fill, with any fuel burp hopefully going back into the tank. Another option is to relocate the vent fitting to some position above the deck, perhaps the outside of a coaming. Yet another option, and perhaps the easiest, is to purchase a fuel whistle that installs in the vent line. This simple device gives you an audible indication of the status of your fill, changing from whistle to warble as the tank nears capacity, then going silent when the tank is full. A fuel whistle will cost you $30 or less, and most marine stores sell them. The only special requirement is that the whistle must be mounted in a near vertical attitude.
Don Casey has written many books and articles on marine maintenance and repairs
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