The dreaded diesel bug!

[stevie69p]

So...apart from giving me an opportunity to get this off my chest, how does it help the OP?

Probably not so much. Other than to say that a cheap little endoscope off ebay is probably worth getting. And even regular doses of Marine16 aren't a guarantee of keeping the dreaded bug at bay.

Oh, yes - and it took me at least 2 pints of London Pride to get the taste of diesel out of my mouth, so plan your post-maintenance regime accordingly.

That's actually all very helpful information, in as much as what I need to be looking out for. Especially the inlet pick up pipe blocking at the tank side of things, as I noticed that when I loosened the water trap drain on the CAV glass bowl, the dark stuff in the bottom was too gloopy to run out, so if similar nastiness exists in the tank, then it needs to be dealt with pronto!

Another problem is the approx 100 litres of fuel in the tank.

 

[thinwater]

... I like the top-loading Racor, but with a little engine (VP2003) I'm worried about the earlier comment that the Racor really needs a stronger flow than the meager 2l per hour we consume....

Raycor works fine at low flow, and the filters last a LONG time.

Bugs can become antibiotic resistant, so if Marine 16 isn't working, switch to Biobor JF (a different biocide).

 

[Dave_Seager]

If the CAV filter is correctly plumbed, the fuel in the bowl has already passed through the filter, which should remove bits of bug residue.

Surely the fuel should go through the bowl to separate any water and sediment before it goes through the filter.

 

[lampshuk]

I'm wondering if some soapy continental lager would be more effective at removing diesel taste?

Yes, but then I would have needed a real beer to take away the taste of the lager ...

...
Pleased to hear you 'got away with it'!

Thanks! I think the poor old engine must have been inhaling through the return pipe. I have in the past got half way down Southampton water with the fuel cock switched off before I suspected anything was wrong.

It did occur to me that the "right" thing to do would be to grab a mooring buoy, or even anchor out of the channel while I sorted the problem, but I was cold and wet and conditions were really unpleasant, and since the engine was restarting so long as I kept the revs up I decided to push my luck. I was nearly at Hythe and if I could make it to the lock I would then be able to rely on my friends at MDL to get me back on the berth.

Cheers!

 

[lampshuk]

Raycor works fine at low flow, and the filters last a LONG time.

Bugs can become antibiotic resistant, so if Marine 16 isn't working, switch to Biobor JF (a different biocide).

Thanks, Thinwater. Useful to know. I've nearly finished the M16 so will try something else.

 

[pvb]

Surely the fuel should go through the bowl to separate any water and sediment before it goes through the filter.

No, if the CAV filter is plumbed following the arrows moulded into the connections, the fuel passes through the filter first. The purpose of this is that the filter medium helps to coalesce minute particles of water into droplets big enough to drop to the bottom of the bowl. Sediment is retained in the filter, which after all is the purpose of the filter.

 

[LittleSister]

In case it's of help to anyone who finds themselves in a similar pickle -

A few years ago my engine started speeding up and slowing down while I was motoring in very lumpy conditions into the wind, then the engine slowed and stopped. I managed to restart it, several times, but each time I tried to rev up to motor forward to ut out. Eventually I deduced the engine would continue to run if I kept the revs very low. (Presumably the blockage was allowing some fuel through, but if the engine tried to pull too much through it just ran short.)

I was able to turn away from the wind, and successfully motored gently back to the marina I'd set out from, negotiate the lock, and berth almost as normal.

So, if you do get your engine stopped by bug (which is what it seemed to be), do check out whether it will run at low revs rather than having no engine at all.

In that case subsequent inspection of the filter showed an amount of black, slimy yuck. I drained the tank (a near bottom outlet, not often seen these days, and a tank that could just be unbolted from the bulkhead, made that unusually easy) but strangely there was next to nothing visible in the tank (good visibility though only for part of bottom of flat bottomed stainless tank). The drained fuel had very little muck in it. I let that settle, refilled the tank and never had the problem again.

(The tank had been drained and cleaned a year or two previously, as some fool (no names, no pack drill) had left the filler cap off and then sailed with the lee rail under, topping the tank up with seawater and washing the side decks with diesel!

 

[lampshuk]

...

So, if you do get your engine stopped by bug (which is what it seemed to be), do check out whether it will run at low revs rather than having no engine at all.

...

Good point. My experience was the opposite: at anything below half speed the engine just died, which made manouvering in the marina a little interesting.

I can see that the behaviour might depend on the exact mechanics of the blockage. A higher flow rate could pull a flap across the inlet pipe blocking it completely, or it might be able to drag fuel past a partial blockage.

The study of Gunge Dynamics. What a glamorous hobby we have chosen.

(and kudos for the water in the tank. My first postings on this forum some years ago related to an embarrassing saga along similar lines)

 

[LittleSister]

The study of Gunge Dynamics. What a glamorous hobby we have chosen.