Is this diesel bug

[Shrimper Bob]

Have just changed my primary (diesel) fuel filter. The old one had a thick layer of black and grey sludgy stuff on top (see photo). Is this the dreaded diesel bug? Filter last changed about 4 years ago. Engine has done approx 100 hours since.

 

[Refueler]

You will now be drowned in advice !!!!

Me ? Thats after 4 years ? Risking being bombed ... not so bad ....

It could be Ashphaltenes ... Wax ..... or dead bug ... unless I could actually have in hand - cannot be 100% positive.

What would I do ? Assuming engine was running fine before ?

Syphon out bottom of tank ... add a good dose of Enzyme Based Bug killer ... let it do its work .... pull fuel through to engine through new filter ... let it stand for a while ... day if you can ... then run engine to test.

If the engine was not running normally and had prompted you to change filter .... then more action may be required than that before running engine.

 

[Shrimper Bob]

Thanks Mudisox - engine has been running perfectly. I only changed filter because I spotted some black stuff on the inside of my tank last time I topped up. Fortunately the tank is fairly easy to get at, and remove if necessary, on my Shrimper.

 

[Obi]

I had it, this is how I dealt with it: I used a pressure pump, hose with in line filters, and oil drums, emptied fuel with the pump into the drums, then reversed the direction and used it to blast out the tank getting right into all corners of the tank with the fuel from the drums and pump acting as a pressure cleaner. I repeated several times until the fuel was clean. Then put the fuel back in, added treatment, changed filters in fuel lines, added another inline filter and never had another problem over 3 years and lots of trips up and down the coasts of W. Europe.

The above solution was proposed to me by a nice S. African live-aboard and he provided the gear to do it. Thankfully the inspection hatches on the tank made this all easy and it was all done in a few hours on a sunny afternoon.

Edit, the repetitions were to ensure the tank was clean just using one drum of fuel for the purpose. The other fuel in the other drums was clean enough having been filtered twice, once on the way out and once on the way back in. Hope that makes sense.

 

[Shrimper Bob]

Thanks Obi. Its only a tiny 18l tank so I don't mind throwing the existing fuel but then I suppose that I do need some medium to circulate the biocide. I do have a small 12v engine oil pump that might work as a pressure washer.

 

[Refueler]

Thanks Mudisox - engine has been running perfectly. I only changed filter because I spotted some black stuff on the inside of my tank last time I topped up. Fortunately the tank is fairly easy to get at, and remove if necessary, on my Shrimper.

Didn't know my name had changed to Mudisox ???

 

[Shrimper Bob]

Didn't know my name had changed to Mudisox ???

Ooops. Soz

 

[Refueler]

Ooops. Soz

No worries ...

Just syphon out the tank ..... if you syphon out all fuel as well ... dose it well ... let it settle ... syphon of clear fuel and discard the mess left in the container.
Put it back in tank ...

I do not advocate filtering instead of settling of fuel out of tank ... for good reason. Filtering does not remove live bug. I don't care what so-called experts claim - I'm in the Fuel Business and it is virtually impossible to filter out live Bug. Only way is to KILL IT and let it settle out.
So you filter after dosing ... you only remove the dead which has joined into a mess .... the individual live are still there being killed off by additive ... Better to let additive do its work ... then just syphon off carefully .... instead of having it all collect in your tank again.

If you decide to dose in tank - then of course letting additive do its work ... I like to leave for couple of days ... then stirring up tank - with a pump then filter and return back to tank - using the return flow to stir up the tank bottom.