Fuel Polisher

[mmarin]

Men,

After a fiasco at sea and not considering the maintenance of my fuel system as a top priority I suffered through an embarrassing and PREVENTABLE mechanical issue.

I had the tank pumped, filled with new diesel and when I reached home, had the tank polished and "cleaned." Given the limited access, I'll assume they did the best they could with the flexible wands, etc., etc.

Anywho, that was then, this is now. I installed a Racor P510MAM fuel polishing system with an automatic timer immediately after the fuel tank cleaning. The P510 is rated at 72 GPH and I have roughly a 237 gallon tank. I run it about 3 days a week for 3 hours at a time.

I recently took a peek at the filtering system and she was spotless and no water. However, after running the boat, my fuel filters had a bit of gunk/slime in them.

I've piped the P510 into the same dip tube that my port engine draws from so I can only assume its near the bottom of the fuel tank. My question is whether the fuel pump on my engine (Volvo Penta D6 IPS) has more "suction" and therefore draws the particles up? Was not a large amount, but my fuel polishing filter was pristine.

Any thoughts.... greatly appreciated!

Best,

Marc

[DeepFrz]

More likely the fuel getting sloshed around loosened up some more gunk. Is your tank baffled and do you have access to each chamber? If not there may be more surprises. I very much doubt that your engine pumps more than 72 gph.

By the way, specs on that system say 60 gph but that is probably at 0 ft. of head.

[mmarin]

DeepFrz,


Good point! I'm going to monitor it and continue to treat with biocides. I've ordered a few diesel fuel test kits to see if the levels of gunk stay static or move.


LESSON LEARNED!

[Lepke]

Are you running bio diesel? Bio diesel acts like a solvent in above 30% mixes. A ferry operator went to 100% bio and made it half way across the sound.
My current boat had sat 6 years when I bought it. I added algae-x and diluted the old fuel about 50% with some new diesel and had no problems. Changed filters before sea trials. No problems. A couple years later I opened the tanks - and went inside. The tanks were clean from the normal circulation. My mains circulate about 70 gallons an hour.
I have been on the water and using diesels for longer than most of you have been alive. I have run military, commercial and large pleasure craft. I usually did the mechanical work so had an interest in not having problems. I have never seen the need for fuel polishing beyond what normal good filtering systems and fuel additives will do.

[SV Allie Rose]

Originally Posted by mmarin

Men,

After a fiasco at sea and not considering the maintenance of my fuel system as a top priority I suffered through an embarrassing and PREVENTABLE mechanical issue.

I had the tank pumped, filled with new diesel and when I reached home, had the tank polished and "cleaned." Given the limited access, I'll assume they did the best they could with the flexible wands, etc., etc.

Anywho, that was then, this is now. I installed a Racor P510MAM fuel polishing system with an automatic timer immediately after the fuel tank cleaning. The P510 is rated at 72 GPH and I have roughly a 237 gallon tank. I run it about 3 days a week for 3 hours at a time.

I recently took a peek at the filtering system and she was spotless and no water. However, after running the boat, my fuel filters had a bit of gunk/slime in them.

I've piped the P510 into the same dip tube that my port engine draws from so I can only assume its near the bottom of the fuel tank. My question is whether the fuel pump on my engine (Volvo Penta D6 IPS) has more "suction" and therefore draws the particles up? Was not a large amount, but my fuel polishing filter was pristine.

Any thoughts.... greatly appreciated!

Best,

Marc

Marc,

How has your P510MAM lasted? I recently picked one up myself for my integrated keel fuel tank, which likewise has very limited access. I was planning on similarly using the same dip tube to draw fuel into the polisher, and from there, either route to a day tank or back into the system somehow (method TBD). Just curious if you have any pictures form your installation or further thoughts?

[Pizzazz]

I do not think there is much point in a fuel polishing system since most big engines draw much more fuel than needed, so it actually gets polished when you run the boat. For example, on my Cummins 450C, the fuel pump delivers approx. 60 gph to the engine and returns 45 gph. With two engines, this is 90 gph fuel polished at cruised speed. With my 450 gallon tanks, assuming half full, the fuel gets polished every 2-3 hours of use. I would be surprised if other engines are much different.

Fuel polishing makes more sense on smaller, trawler type engines that use less fuel and have much bigger tanks. But for most fast cruisers, it is redundant. Just change the filters more often.

[Sailorman97]

I had a fuel polishing system. I don't any more.

Having looked at a few opened old fuel tanks and seen where the suction tubes end up I can state with absolute certainty that an onboard fuel polishing system does not do anything and can not do anything unless fuel suction tubes are extended to the bottom of the tank.


First off unless your suction tubes go to the very bottom you can not polish all the fuel because you can not even get to the stuff on the bottom. Second the fuel pump you are using is not going to really stir anything up with the small amount of return fuel. This is maybe different if your in a power yacht with a pair of 400 hp cats or similar but no sailboat engine is going to move enough fuel to stir up anything. It certainly is not going to break up an algae mat. The simple fact that your engine is able to run means your not sucking up water from the bottom of the tank so if there is water and algae there you are not sucking it up.

Every older diesel tank I have opened has had water in it from just below the fuel suction tube including mine. My fuel tanks purported to hold 500 liters. I decided to inspect them and after the electric fuel pump ran dry and had done all it could I opened the tank to see what was there and there was a lot of fuel there below the level of the suction tube. The suction tube was 2 inches off the bottom of the tank.

With an oil change vacuum I sucked up 25-30 liters of fuel out of the bottom of that tank. When I ran this through a water separator low and behold it was all water and algae out of the bottom of that tank. Almost no fuel at all.

I have come to the conclusion that the only way to avoid the bugs is to use a biocide and as much as possible keep water out of your tanks and the only way to do that is to configure your fuel system so that it takes fuel off the very bottom of the tank. This means that if there is any moister there it gets sucked up and separated in your water separator . You need to watch this fuel separator all the time, preferably with a fuel filter water sensor that Racor sells. If you do that there is no need for a polishing system.

Then there is the bugaboo about making sure the fuel tanks are full for the winter so they don't condensate. Well many of us did not use the fuel we had 3 yrs ago. I know I did not. So if you top it up every year you never ever use up the old fuel and have fresh fuel. You just keep topping up the stale fuel with fuel that will soon be going stale.

When you read the next part you will see this is not required or even helpful.

I have a marina buddy who is a diesel engineer and he used to run service on 400-500hp ( i need to confirm size) diesel generators in out of the way places in the world. By a simple calculation we can assume they are using say 30 US gallons per hour or 700 gallons a day.

By my recollection of what he said, they would fill a clean day tank with clean (dry no water) fuel and run that machine on that tank for 24 hrs and at the beginning of the next day would switch to another day tank and would then drain 2 or 3 gallons of water out of the previous day's tank before they refilled that in preparation for the next day.

Where did all that water come from? Condensation from hot fuel. Cold fuel going through a hot engine comes out hot on the return and goes back into the tank and condensation forms.

I never thought of that till he told me. Our boats have the same problem to a much lesser degree. Impossible to keep water out of the fuel. He confirmed this to me.

Once you think about this for a bit you can see the futility of leaving your diesel tanks full every winter when you do not even burn off the fuel you had on board 3 yrs ago. All your doing is ensuring that you will always be using stale diesel fuel. (yes that is a thing)

In my mind, what is required is 2 good Raycor FG 500 turbine fuel water separators with bowl probes to sense if there is water in the bowl. You set the probes up on an alarm system. You set these filters up in parallel so that only one is being used at a time but so that you can switch over from one to the other in a flash. As soon as you have a fuel problem or a water alarm you look at the filters and swap if required by the simple expedient of 4 valves. Open 2 to bring the new filter on line and close 2 to isolate the old filter. Now you can do what is required to fix the problem filter

If you have any fuel pump between the tank and the filters relocate them to after the FG500s. Raycor says the pumps have a tendency to emulsify the water in the fuel and it can't be separated out.

With that in mind I also took out the 2-30 micron pre-filters I had before the FG 500s. If going through a pump is going to emulsify the water into the fuel then going through a filter is going to do it too.

As I said, I was sold on my fuel polishing system until I could see that it did nothing.


PS: If you put the suction tubes to the bottom you need a coarse screen on the tube to make sure nothing too big gets sucked in. Some of the sealant I used to seal the inspection ports fell into the fuel, hardened and then got sucked up and clogged the suction tube. That was rather hairy.

[Pizzazz]

On my boat, the fuel pick up line goes to the near bottom. Next to the fuel pick up tube there is another tube with a manual push pump that goes all the way to the bottom. Riva recommends that you use the manual pump to drain the water that accumulates at the bottom. I think this is a good setup that can be added inexpensively to many existing tanks. It is so much easier to pump a couple of times than to clean the tank.

[noelex 77]

Originally Posted by Sailorman97

and can not do anything unless fuel suction tubes are extended to the bottom of the tank.

The polishing pickup should be located at the very bottom of the tank, below the pickup for the main engine.

Originally Posted by Sailorman97

Second the fuel pump you are using is not going to really stir anything up with the small amount of return fuel.

Agreed. The polishing pump will not stir up the tank. This is why polishing should be done while sailing or in a rolly anchorage. The boat motion will stir up the tank. This is why people invariably first notice a fuel problem on a rough passage.

If you have a day tank it is even possible to have the ideal situation which is collecting the engine fuel in calm conditions and polishing the fuel while the tank is agitated.

[noelex 77]

Originally Posted by Pizzazz

With my 450 gallon tanks, assuming half full, the fuel gets polished every 2-3 hours of use.

This does not apply to yachts. A polishing system will process much more fuel than the engine.

The photos below visually show the difference. These two filters are the same age and the same micron rating (I normally use a finer polishing filter).

Both filters are fine. The fuel is very clean, but you can see the engine filter (on the right) is looks absolutely brand new. The polishing filter (on the left) has obviously processed far more fuel. It has filtered around 400,000 litres at this stage.

[Sailorman97]

Originally Posted by noelex 77

The polishing pickup should be located at the very bottom of the tank, below the pickup for the main engine.



Agreed. The polishing pump will not stir up the tank. This is why polishing should be done while sailing or in a rolly anchorage. The boat motion will stir up the tank. This is why people invariably first notice a fuel problem on a rough passage.

If you have a day tank it is even possible to have the ideal situation which is collecting the engine fuel in calm conditions and polishing the fuel while the tank is agitated.

A rolly anchorage will do nothing to cause mixing of the fuel, algae and water. Even a rough passage will not to much unless it is really bad. If you have ever seen this algae and water it is pretty stable. It would have to be a really rough passage and for a long enough duration to cycle through all of the fuel for quite a while.

Seems impractical.

The day tank idea is a good one except most sailboats would not room for one.

[Sailorman97]

Originally Posted by Pizzazz

On my boat, the fuel pick up line goes to the near bottom. Next to the fuel pick up tube there is another tube with a manual push pump that goes all the way to the bottom. Riva recommends that you use the manual pump to drain the water that accumulates at the bottom. I think this is a good setup that can be added inexpensively to many existing tanks. It is so much easier to pump a couple of times than to clean the tank.

Someone was thinking there. Good idea. Makes the whole process very simple. Suck the stuff off the bottom and you get the any water. I could see ending sucking diesel fuel as well as your trying to get the sludge. Just need to be prepared for what to do with it.

Anyone ever notice that big construction equipment does not seem to have these issues?

[noelex 77]

Originally Posted by Sailorman97

A rolly anchorage will do nothing to cause mixing of the fuel, algae and water. Even a rough passage will not to much unless it is really bad.

Using this logic, the engine that has higher pickup than polishing would never have any water or algae problems.

This would be nice if true, but unfortunately these issues are not uncommon.

[Sailorman97]

Originally Posted by noelex 77

Using this logic, the engine that has higher pickup than polishing would never have any water or algae problems.

This would be nice if true, but unfortunately these issues are not uncommon.

Rolly anchorages will not mix fuel. Very rough passages will. The amount of mixing that goes on depends on the level fuel in the tank. If it is almost full I bet it is next to none will occur but if it has lots of space in an almost empty tank the you can bet there will be lots of sloshing.


If you actually think about the number of boats out there and the very low levels of maintenance they get it is actually not very common to have the problem to the degree that it affects anything.

We came up the Atlantic coast in terrible weather and had no problems but a year later I opened the tank and found 25-30 litres of water in the tank.

My buddy did the same trip in a sister ship and his ride was brutal and he had no problems until he was on Lake Ontario for 2 yrs. When he open the tanks and clean them his results were similar to mine. He started having problems while in the 1000 Islands which is not noted for its tough conditions and big wave

That says to me that you don't see the problem till the water gets to the level of the pick up or really close.

[noelex 77]

Originally Posted by Sailorman97

If you actually think about the number of boats out there and the very low levels of maintenance they get it is actually not very common to have the problem to the degree that it affects anything.

Acording to Nigel Calder:
"90% of diesel engine problems result from contaminated fuel.”

For long distance cruising boats that often have to fill up from questionable sources, diesel bug problems are common in my experience. With the advent of common rail engines and the push to incorporate biofuel into diesel these issues are only going to become worse.

Originally Posted by Sailorman97

We came up the Atlantic coast in terrible weather and had no problems but a year later I opened the tank and found 25-30 litres of water in the tank.

Wouldn’t it have been better to be running a polishing system with a pickup at the bottom of the tank to remove the water before it reached this level? On an Atlantic crossing some of this will be emulsified in the fuel and risks damaging the injectors.

However, this shows that that there are many steps needed to deliver clean (and water free ) fuel to the engine. This large amount of water suggests the seal on the diesel filler cap was leaking (although this not the only possibility). On many boat the diesel fill is located on deck, in one of the wettest parts of the boat. It relies on single ”O" ring to keep water out. This is a crazy design in my view.

Polishing is not the only step that helps provide clean fuel, or even the most important. It does not mean other steps such as picking the best quality fuel available, sampling and filtering it before it enters the tank, using a biocyde etc can be neglected.