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Contamination in diesel tank

On dipping my tank, I'm picking up some mid-brown stuff on the end of the dipstick. There's probably no more than 1 or 2 mm of it. Should I do anything about it? Our engineer thinks it could be due to overdosing Fuelset - I don't particularly think I have overdosed but I may have erred on the generous side rather than on the mean one as it is not always easy to be sure how much the tank will take. He think it wouldn't be picked up by the intake and, if it was, the filter would deal with it. He suggests if I want to be ultra cautious I could get the fuel polished.
What would you do in our circumstances?

Asked by: Clive Dutson  | 5.22pm, Monday 8 September

WW says:

Fuel set could be an issue- it tries to emulsify any water into the fuel so that it can be Burnt- however it had a habit of settling out when the fuel is not disturbed- ideally it likes the tanks being agitated- great on a yacht or seagoing boat, less practical on a narrowboat.
The "muck" that you have picked up could also be the start- or potential breeding ground- for diesel "bug"; a mixture of organisms that love in water and use the fuel as a carbon source. Removing it would be ideal- hopefully you have a pre filter fitted before the filter on the engine. This, as your engineer points out, should remove contamination- but if the contents are agitated such as on a river, then the pickup might take contaminated fuel which can overwhelm the filter and cause fuel starvation.
You might consider draining fuel from the base ofthe tank- if you have a drain point fitted- as this will enable you to remove any water and gunk, until you get to clean fuel.
Polishing would work- though, depending on his you use your boat, fitting your own system may be more pragmatic in the longer term than having a yard do it. We will be covering the installation of such a system in WW soon.
You might also consider using a fuel treatment which promotes water to seperate out (where it can be filtered out or drained off) rather than emulsifying it- which can lead to sludging. river canal rescue RCR recommended Marine 16 as it works well at precipitating water and it is very effective against microorganism contamination as well.
Let us know if we can be of any further help.

Mark Langley  | 10.54PM, Monday 8 September

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