Re: Paranoia about the D3-110 Volvo Penta - diesel bug
There are only two ways to keep your fuel tank, when you store a boat:toggle quoted messageShow quoted text
1) completely full, to the top
2) bone dry, empty.
The reason is that during the course of the day, air expands and contracts. If there is an air space in your fuel tank, air is constantly flowing into and out of the tank through the vent line, due to the normal expansion and contraction of air as the temperature rises and falls during the course of the day. The problem is that the fuel, a liquid, with a much higher specific heat (capacity to hold heat)remains at a more constant temperature. This heat sink of the fuel in the tank causes much of the water vapor in the air, to condense to liquid water in the tank. Only a little bit every day. A few months of this activity in a relatively humid (sea air) environment can produce a significant amount of liquid water, that settles to the bottom of your tank.
Diesel bug is an algae that has developed the ability to survive by eating diesel fuel, and using the water at the fuel water interface to get oxygen. So the bug lives, reproduces and dies in that fuel/water interface, producing the black gooey sludge.
Having a partially empty tank exacerbates this problem.
Storing your boat with completely full tanks eliminates the air space, so moist air does not get in and can’t condense its moisture in the fuel. An empty tank (difficult to do) doesn’t provide the heat sink to cause the water to condense so fast. It will to some extent, but not so rapidly.
We’ve experienced this first hand. After cleaning our tank we were bug free for about 5 years, traveling through The Caribbean, storing the boat every hurricane season in the tropics. One season, we forgot to fill the tank, and had diesel bug the next cruising season.
I also think using Biobor or equivalent, is a good thing.
On Feb 9, 2020, at 9:28 AM, Scott SV Tengah <Scott.nguyen@...> wrote: