diesel microbes doing their thing
Wednesday, January 18, 2012 at 21:40
Eric in diesel, maintenance

Gross. Click to enlarge.Water ends up in a diesel tank, and up to 27 different types of bacteria can live in the barrier between the two fluids, essentially "eating" the diesel. As much as that grosses me out, I have to admit that's some pretty hardcore bacteria. I mean really, could you eat diesel?

Last year I cleaned out the tank (act one, act two) and although there are lapses in maintenance overall I'd say I keep the fuel system pretty clean.

On my twin Racor setup one of the filters was getting a lot of use and the other essentially sat idle for a year with a bit of water at the bottom. I'm not sure how many of the 27 strains of bacteria grew in that bowl, but you can see for yourself in the picture below that the gunk was pretty foul. 

Beyond cleaning your tank, there's a lot of debate about how much the "keep your tank full" wisdom really matters. Having less fuel doesn't allow more water to condense; the water is in there or it isn't. Regardless, a good biocide is in the cards. 

The only biocide that Yanmar recommends is Killem FPPF, I'm assuming because it acts in the water area and not the fuel. So if you have a water separating filter (like Racors), the biocide itself should never get into the engine. 

While I'm on my soap box, let me bash "fuel polishing". I aimed a garden hose full blast at the crud in the bowl there (which is very similar to what's on the bottom of most diesel tanks), and maybe 90% of it came off. And that's full blast with a garden hose. Fuel polishing achieves nothing like that type of pressure or agitation, and as such will even get worse results.

It's simple: if you have crap in your tanks you need to clean them out. If you clean them, you don't need to polish your fuel. And polishing your fuel won't clean your tanks. The logic is unfailing no matter how much anyone out there wants to convince themselves why they don't need to potentially cut access ports in their tanks and clean them out. 

Article originally appeared on Rebel Heart (http://www.therebelheart.com/).
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