Gunge in fuel question

[webcraft]

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If I run the engine coming to anchor in shelter immediately after a washing machine episode there is whitish gunge in the filter bowl after only a few minutes. In calm conditions though I can run the engine for hours and it stays clear.

Is it most likely to be:

a) Diesel/water emulsion
b) Bug
c) Non-specific crud
d) A mixture of two or more of the above
e) None of the above?

I think it is a), but how can I tell for sure?

(I intend to drain the tank, take off the inspection plate and clean it out anyway when the opportunity presents, just wondering if I should treat for bug)

- W

 

[Yngmar]

If it's a), it should separate back into fuel and water after a night of rest.

If you have an aluminium tank, it could also be e) Tank corrosion

Or you got some dodgy fuel complete with someone else's white gunge pumped into your tank.

Fuel bug treatment would not help. Fuel bug isn't white gunge, it's black. Some of the treatments work by removing the water in the tank through blending it with the fuel, but then in case of a) you already have that happening

 

[[70521]]

What does the filter look like?

This is mine with the bug

https://flic.kr/p/XWKjmd

 

[jdc]

I suspect it isn't emulsion because even in rough conditions I doubt that the water and diesel will mix to an emulsion so fine you couldn't see droplets. But this is only a 'probably'.

I have seen pale grey (the colour of dry cement or a bit paler) crud in my separator which turned out to be silt, presumably wind-blown, which I think we picked up when refuelling in Norway.

The v useful pic above shows microbial growth, which is red or brown. Black gunge is usually from asphaltanes due to fuel decomposition, not from microbial growth imho.

To be sure I think you have to drain it off and see how it separates out, or filer it and rub the deposit in your fingers.

 

[lw395]

If this is in the bowl of a CAV filter unit, it has been through the filter element.
I would suspect it's water with some byproduct of a fuel treatment in it.