Should I be worried?

[down...2 greens]

....about diesel bug?

I did a routine change of the fuel filters on my boat yesterday. I usually do it annually, although this time it's been just over 18 months. I use Fuel Set additive at every fill and engine operation has been normal, with no water or sediment visible in the glass bowl of the CAV filter at any stage. Still, out of curiosity I decided to have a look inside the old filters.

I was a bit shocked to find the primary (water separator) filter looking black inside, although with no signs of sludge. It's the first time I've cut a filter open so not sure what to make of it, but it wasn't what I expected to see. The secondary filter (on the engine) looks clean (last picture).

Pics attached below - I'd be grateful for thoughts from the panel!

 

[PaulRainbow]

Hard to be sure from a couple of pics, but that looks more like Asphaltenes than bug. Pump a litre out into a clear container and let it settle, see what it looks like then. Asphaltenes will settle to the bottom and look a bit like creosote.

 

[V1701]

Well it certainly looks like they're doing their job! Out of curiosity approx how many hours run during that time?

 

[down...2 greens]

Thanks Paul, I’ll give that a go when I’m back at the boat. There’s a drain point at the bottom of the tank so that should give a good idea (although I only recently refilled the tank from almost empty).

Hours-wise I‘d find it difficult even to guess. It’s an ancient VP2001 with no hours counter and I’m not quite disciplined enough to keep track!

 

[down...2 greens]

Well I got to the boat this morning and drained off a litre or so from the bottom of the tank into an old cafetière. Still no evidence of any water but some small bits of brown/black sediment settled to the bottom. I'm not sure how much use the pictures below are, but I'm hoping for some suggestions about what to do next. (The second picture is looking at the bottom of the container from underneath.)

 

[garymalmgren]

The filter stopped that stuff from getting to the pump and injectors.
That is a win!!

gary

 

[peter gibbs]

Well I got to the boat this morning and drained off a litre or so from the bottom of the tank into an old cafetière. Still no evidence of any water but some small bits of brown/black sediment settled to the bottom. I'm not sure how much use the pictures below are, but I'm hoping for some suggestions about what to do next. (The second picture is looking at the bottom of the container from underneath.)

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View attachment 129973

Most of us have some flakes af the bottom of the tank but not a cause for concern - the filters will deal with them if changed every layup. Engineers say fuel filter changes are the best use of your last boat buck!! How true. Even over oil filters.

But residues that look and feel organic are something else and must be eliminated. Your dismantled filter doesn't look threatening - organic is not likely to be that evenly spread so could be just surace treatment. Clean second filter almost certainly proves you're good to go.

 

[[70521]]

This is my experience of the dreaded diesel bug.

 

[down...2 greens]

Thanks everyone - the sediment in the tank didn't look especially serious to me but I'm still a bit concerned by the black coating on the filter. Then again I've never cut one open before, so maybe it's always like that!

I didn't see anything like in your picture Sandy - out of interest, was there anything visible in the fuel in the tanker was it all trapped in the filter? And how did you manage to get it sorted?

 

[[70521]]

I didn't see anything like in your picture Sandy - out of interest, was there anything visible in the fuel in the tanker was it all trapped in the filter? And how did you manage to get it sorted?

Good to hear that you did not have that horrid brown gunk.

The fix was as:

Remove the tank and steam clean, remove all of the pipework and replace as it had been in situ for 35 years and had seen better days, I actually replaced the CAV filter unit with a top loaded as changing the filter at sea was a vomit inducing job. Changed to white diesel as am convinced this was picked up at a supplier with very low turn over of red.

 

[Porthandbuoy]

Do you have a priming bulb in the line?
I had similar black fine stuff captured in my CAV primary filter after the bulb had been installed a couple of years. Like yours, the secondary filter was clean.

 

[down...2 greens]

Nope, no bulb - it's a direct (and short) connection from the tank to the CAV.

So the general feeling seems to be to leave it alone for now and see what happens?