Cloudy diesel

Poey50

Poey50

Well-Known Member
Joined
26 Apr 2016
Messages
2,319
Location
Chichester
Visit site
I made a fuel polishing system around a Racor 500FG 10 micron filter and polished the fuel about six weeks ago. The intake tube went right to the bottom of the tank and took out quite a lot of slime and water. The filter was so clogged I changed it and then polished the fuel for 2 hours. It then looked clear on sampling.

Over the weekend I was surprised to see the fuel looked cloudy in the glass bowl beneath the primary filter. There was no obvious effect on the engine but it's not something I'd like to continue with.

My questions are ...

1. Although I can see that the Racor is good at removing free water, how good is it at removing emulsified water?

2. Would a 2 micron filter in the polisher be better at removing cloudiness?

3. Is there a treatment (that doesn't' have harmful side-effects) that turns emulsified water into free water?

4. Does temperature effect cloudiness or must more water have got in over the last month to account for the cloudiness after polishing?

5. Is there anything else I can do?

Thanks in anticipation ... :)
 
If you have "free" water in the Racor, you have free water in the tank.

A better filter will only reduce cloudiness if it is due to particulates in the fuel (including bug crap).

There are additives to encourage emulsification, to enable the emulsified water to pass through the combustion chamber into the exhaust. I know of none designed to do the reverse.

Water may get in via the filler if it's not tight. Mine has an O ring seal beneath the cap. It shouldn't get in by the breather, but I'm assured that it can so check where it is and if the outlet is liable to be covered by water on a particular tack.

You must ensure that the tank is clean. The best results are from removal, emptying, stem cleaning, drying and replacement. I have friends who have washed the tanks with washing up liquid and dried them with a paint stripper gun. They have reported this method as successful. See also the comments regarding the filler and breather. Even when the tank has been cleaned and refilled with fresh fuel, it is advisable to dose the fuel with a biocide as the bugs will lurk in the pipework and filter system. Replace the fine filter as well as the Racor filter (there will be one).
 
As I said elsewhere on here if I were you dump the old fuel.As for drying I am about to finish mine off in situ with a squeegee mop and squeezer and then let the summer(ashore) finish the task.
A good quality concentrated commercial detergent works wonders as does a dish wash brush on a length of dowel!
I also made up a water jet with straight and angle adapters from 10 mm copper pipe and fittings to pressure wash the tank.
A litre of domestos is also good in a tank filled with water-the bugs dont like it!
 
Superheat6k (whose business is fuel related) recommends that in a filtering /polishing rig, the pump must be downstream of the filter, so that it sucks fuel into the filter. If you have the pump upstream of the filter, the vanes/pistons can break up the water particles so that they pass through the filter.
 
Thanks for the replies so far. For information ...

- there is no free water in the glass base to the filter just cloudy looking fuel. No free water appeared in the glass bowl despite a couple of hours of motoring,

- the fuel polishing of a few weeks ago removed all free water and slime (I can move the inlet hose around the base of the tank and no more came out after 30 minutes of hunting it down),

I'm surprised if extra water got in. The sealing ring is good and I buried the filler cap threads in grease. Water can't pool around the cap.

- the tank would be a nightmare to remove - it would be easier to buy a new boat (which is not going to happen).

- the pump of the fuel polishing rig is downstream of the filter as recommended.

- I'm not going to be heating up the fuel but I do wonder if the cloudiness might clear as the air temperature heats up.

Current plan is to decant all the fuel (77 litres) into cans via the fuel polisher and bring it home to polish again perhaps with a 2 micron filter. Then start afresh.
 
Last edited:
savageseadog said:
Best way of separating water from fuel is to heat it up.
Click to expand...

I think the solubility of water in diesel increases with temperature, so heating it would encourage the water to dissolve.
This will make the diesel clear, but the water won't have gone away.
Cooling it will encourage water to form cloudy micro-droplets.
 
Poey50 said:
Thanks for the replies so far. For information ...

Current plan is to decant all the fuel (77 litres) into cans via the fuel polisher and bring it home to polish again perhaps with a 2 micron filter. Then start afresh.
Click to expand...

I am curious about this thread, so a serious question, can someone explain to me what problem is going to occur if the OP just uses his filtered cloudy diesel?
 
Once polished, add a biocide and/or something like Soltron to the "old fuel". If it were my boat, and 77 litres was involved, I'd add the polished fuel back in with fresh at around 15l/tankful, but my family would be the first to acknowledge the fact that I'm parsimonious to an extent that would make an Aberdonian Blush and even a Yorkshireman suck his teeth.

When I last had a bio contamination issue, the tank came out and was steam cleaned. This produced pinhole leaks which had to be welded up (it's SS) then replaced. I was daunted by the task but actually the person who fitted it originally (not me) did a proper job and it was a lot easier than I thought.

Good luck!
 
Quandary said:
I am curious about this thread, so a serious question, can someone explain to me what problem is going to occur if the OP just uses his filtered cloudy diesel?
Click to expand...

As the OP has already done a couple of hours motoring using the cloudy fuel, I think the answer to that is "none".

I would just use try a water-remover additive like Wynns or Valvoline or one of the biocide-type additives which do the same kind of thing.

https://www.amazon.co.uk/Wynns-71867-325ml-Dry-Fuel-x/dp/B006I4AHNC

Richard
 
Last edited:
Thanks RichardS ... I've ordered some of that.

Your comment also raised another thought. I used Marine 16 Diesel Fuel Complete for the first time after the last fuel polishing. Could that result in the cloudiness which, as you say, does not appear at the moment to be adversely affecting the engine?
 
As above ... has anyone found that Marine 16 Diesel Fuel Complete creates some haziness / cloudiness when fuel is first treated?
 
Poey50 said:
As above ... has anyone found that Marine 16 Diesel Fuel Complete creates some haziness / cloudiness when fuel is first treated?
Click to expand...

I haven't found that with the Marine 16 Fuel Treatment (the clear stuff). I have a bottle of the brown Fuel Complete but haven't used it yet. However, I haven't heard that it creates cloudiness and, if it did, I'm sure that it would mention it in the instructions.

Richard
 
RichardS said:
I haven't found that with the Marine 16 Fuel Treatment (the clear stuff). I have a bottle of the brown Fuel Complete but haven't used it yet. However, I haven't heard that it creates cloudiness and, if it did, I'm sure that it would mention it in the instructions.

Richard
Click to expand...

OK thanks Richard.
 
Poey50 said:
Thanks RichardS ... I've ordered some of that.

Your comment also raised another thought. I used Marine 16 Diesel Fuel Complete for the first time after the last fuel polishing. Could that result in the cloudiness which, as you say, does not appear at the moment to be adversely affecting the engine?
Click to expand...

You should have said so before!
Seems possible there was more water than the additive could cope with?
 
I would leave the polishing rig running for several hours circulating the tank, then I would use a chemical like fuel set as this dissolves / breaks down the water into the diesel so it then burns through the engine. I do not routinely use additives, but would use this for the situation you describe.

The Racor filters are excellent but do require a reasonable flow rate to have the centrifugal separation affect work. I think the simpler Baldwin PF10 element fully immersed provides a better coalescing surface to collect the water into droplets large / heavy enough to drop down into the separator bowl, whereas the Racor is primarily filtering our crud particles above the element micron rating, and relies to some extent on the centrifugal action spinning the heavier water out. Water as a liquid can reduce in size below the micron rating without emulsifying, I suspect you are simply obtaining clean, but cloudy fuel as a result.

I would echo what Sarabande has said that drawing the fuel through the filter rather than pushing it through is essential, but sucking does reduce the flow rate achievable substantially if using a small pump.

Then the obvious, but often overlooked - is your deck filler seal working ? A decent O ring and plenty of grease.
 
Quandary said:
I am curious about this thread, so a serious question, can someone explain to me what problem is going to occur if the OP just uses his filtered cloudy diesel?
Click to expand...
I for one would not be happy at all with cloudy fuel going through my injection pumps, especially as the OP has good reason to suspect this is water as he has after all found free water already. Water in fuel injection pumps in any quantity is very bad news IMHO.
 
You must log in or register to reply here.

Share this page

Top