Fuel Polish MS 400

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davidla

Veteran Member
Joined
Jul 9, 2023
Messages
55
Vessel Name
Shady Lady
Vessel Make
Main ship Trawler 400
Hi,
One of the recommendations from my recent survey for purchase (signed a contract btw). Was to clean the fuel tanks as boat has been sitting for awhile.
Has anyone set up a fuel polish system between the port and stardboard tanks using the cross over? I will be getting a service with new filters etc but would still like to consider a polish.
If so could you publish the details.
Thanks and regards,

David
 
If the tanks are really dirty you would be better served by hiring a service to come clean the tanks and fuel. Most onboard polishing systems do not develop enough volume and flow to clean a dirty tank. They can help keep it clean once it has been cleaned.
 
Thanks, not sure if such a service exists here but will find out.
 
They would likely put inspection ports into the tanks and pump the fuel out, filter it and return it to the tank with enough force to dislodge any debris in the tank and then suck the debris up and filter it out. No onboard polishing system has enough flow and force to do that.
 
I suspect this is a boilerplate recommendation.

Fuel gets polished as soon as you start operating. Your regular filters and separators *should* be able to deal with it, but extra vigilance is called for.

I'd be particularly alert for water early on, and crud the first time you're out in rough conditions.

The last boat I bought had been very lightly used and then ashore for several years when I bought it. I went through two fuel filters running the old fuel down, then cleaned the bowls and assemblies, and it's been clean since.

It makes more sense to me to spend your time and money on making sure the primary filtering system is in top shape rather than installing a separate polishing system. There are lots of threads here on that. Vacuum gauges and switchable filters allow you to recognize and deal with a clogged filter. It shouldn't be a show stopper.

And congrats!
 
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Here`s one:https://www.mobilemarineservice.com.au/about-us. I know nothing about them, it looks expensive. Maybe the surveyor knows someone.
The muck is likely on the bottom of the tank so has to get stirred up, a filtration system won`t do that. When my boat was delivered Melbourne>Sydney the guys took extra filters, changed once en route, it arrived with flat pieces of black crud sitting in the glass bowls of the filters. Did an oil change, no recurrence.
 
For what it's worth, another MS owner made the point that the fuel feed connection is at the bottom on the tank, aft end, and not a dip tube like other boats. His theory is that the fuel is constantly being polished by running the engines because it is picking up fuel and anything else on the bottom of the tank and constantly running it through the filters. Thus the fuel stays pretty clean as long as you change the filters.

When I bought my 400 I looked into having the fuel polished but there are no inspection hatches and access to the tank is limited to the top where the float gauges are bolted on. There isn't much room there, so the company I talked to wanted to cut hatches to do the job. I don't know how they would have room on my boat as I have twins and the tanks are blocked by the engines. With a single it may be easier.

In the end, I opted to just go ahead without polishing and after almost 5 years have had no issues. The fuel seems to stay clean with the existing setup.
 
We have a on board fuel polishing system, but if the boat had been setting for two or three years I would definitely suggest a fuel polishing service the volume of fuel they run can not be compared to what you can get with your standard onboard system. You need the high volume to clean the tank.

Do an internet search for "Marine Diesel Fuel Polishing near me".
 
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Thanks all. Will have a look at the setup on board when I take ownership and see what can be done. I like the fact you could polish from one tank to the other...
 
The photo shows what the first filter looked like during the tank/fuel cleaning before changing to another filters to finish the process. Our Racors stay far cleaner now than before plus no frequent filter changes. Money ($450) well spent
 

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There is an unused dip tube on the port tank near the center that can be removed for access to suck the fuel out of the tank. On the Stb side near the aft end there is an unused pick up that is marked something like "Gen Pick Up" that can serve the same purpose.



Obviously, neither of these is big enough to provide enough access to clean the inside of the tank. They would need to cut access plates to do that.
 
And it also depends on your engine fuel return rate. The Lehmans return almost nothing and Detroits return a lot. But usually fuel return won’t clean a very dirty tank but maybe it will keep it clean once it has been cleaned. Really the only good way to clean a tank is to open ports up and use the fuel as a wash down. The problem is when you don’t have inspection ports. But fuel polishing services deal with that all the time. Just find a good polishing service.
 
I have opened up a stainless tank and a black iron tank on a 1974 Willard. Both were coated with a black substance that required swabbing with a cloth to remove. Polishing would not have removed this contaminant. It did clog the filters every 20 hours or so until it was physically removed and the tanks scrubbed and cleaned thru large inspection holes (6" dia.). I had an issue with a leaky Stbd tank in my MS350. I had to cut an inspection hole to gain access to repair and found similar black residue in that tank but not as bad as the Willard. My experience is the only way to really clean a dirty tank is physically. I don't believe polishing will do the job. Polishing will take out the contaminants that are currently in solution, but the "slime" on the walls will continue to be there and contaminate the fuel but at a slower rate maybe. Having a "quick swap" set of good filters have served me well for decades. A filter change every 40-50 hours is a lot cheaper and probably as good as polishing. Just my experience, yours might be different for sure.
 
We bought a 1974 Cheoy Lee Pilothouse Trawler three years ago with between 600-650 gallons of the dirtiest, most contaminated diesel I have ever seen. Before taking it up the Pacific Coast to the Straits of Juan de Fuca and then Puget Sound we had the fuel polished and tanks inspected. Because the two main saddle tanks and a low, long center tank were integrated into the hull from the factory, there were none of the rust or seem issues that plague many older vessels. The 30" round inspection ports made it where one could actually climb in to get a good look at the baffles and interior walls. The center tank only had a 12" round inspection port. Using filtration down to 0.2 microns with a large high volume 220 volt ac pump we could spray ultra clean diesel into tanks like a pressure washer shooting clean diesel to clean in inner parts. Then cycling all this through a second and third time. We went from two Racor filters every 20 minutes to using the same filters for almost 800 nautical miles. Vacuum gauges still never registered a need for changing them, it just came with annual oil, impeller, transmission fluid, pencil zinc change(s).
I have been very happy with the cost to benefit ratio of this service in the PNW.

Do you think having had this service done and kept video proof of the great condition of the tanks will add to resale value as well as the savings on filters and peace of mind?
 
We bought a 1974 Cheoy Lee Pilothouse Trawler three years ago with between 600-650 gallons of the dirtiest, most contaminated diesel I have ever seen. Before taking it up the Pacific Coast to the Straits of Juan de Fuca and then Puget Sound we had the fuel polished and tanks inspected. Because the two main saddle tanks and a low, long center tank were integrated into the hull from the factory, there were none of the rust or seem issues that plague many older vessels. The 30" round inspection ports made it where one could actually climb in to get a good look at the baffles and interior walls. The center tank only had a 12" round inspection port. Using filtration down to 0.2 microns with a large high volume 220 volt ac pump we could spray ultra clean diesel into tanks like a pressure washer shooting clean diesel to clean in inner parts. Then cycling all this through a second and third time. We went from two Racor filters every 20 minutes to using the same filters for almost 800 nautical miles. Vacuum gauges still never registered a need for changing them, it just came with annual oil, impeller, transmission fluid, pencil zinc change(s).
I have been very happy with the cost to benefit ratio of this service in the PNW.

Do you think having had this service done and kept video proof of the great condition of the tanks will add to resale value as well as the savings on filters and peace of mind?

That is a great way to do it. If only all boats came with fuel tanks like that…
 
If the tanks are contaminated, i.e. the tank and not just the fuel, a polishing system probably isn't the solution, although it won't hurt. The sure-fire solution is to access each baffled chamber of the tank, using inspection ports, adding them if necessary, and carry out cleaning using these, more on how to do that here https://stevedmarineconsulting.com/cleaning-diesel-tanks/

If there is accumulated debris on the tank bottom, the only way to remove it, in my experience, it by getting to it, and scraping, scooping and washing it out. Dockside tank cleaning services that don't enter all baffled chambers are of limited value for the money.
 
I have often thought of buying one (or two) of these.
https://www.go2marine.com/Racor-Multipass-Pump-and-Filter-Fuel-Polishing-System?

But, the reality is we are 100% liveaboards and it is rare for the boat to sit idle for more than a week or two. Because we are frequently taking on fuel and using it, we don't seem to have this problem.

Three years ago when this 2000 MS 390 was new to us, we took it across Block Island Sound to Long Island then to the South Shore of Long Island. Within a month, the classic signs of needing to change fuel filters popped up.

CAT 3126 has a 2 micron fuel filter on the engine's port side, and the Racor before that had a 10 micron element. Mechanic #1 said use a 30 micron instead of the 10. Mechanic # 2 said keep using the 10. So, it'll be "fun" to hear everyone weigh in on that! LOL

We added the differential pressure gauge that goes atop the Racor, and I find that to be worth taking a picture of when I check the oil.
https://shellerina.com/2022/10/22/a-productive-saturday/

IF we had "ongoing problems" with this, which we have not, adding a second Racor 30 micron to then feed the Racor 10 micron, to then feed the CAT 2 micron would be worthy of consideration. But we've put on nearly 10,000 miles in 3 years and [knock-on-wood] have been fortunate. No signs of bad fuel or crap in the tank. I just change the filter elements when the differential pressure appears to be telling me "It is soon going to be time."

I did add a new Racor filter housing to the Generator, as the mechanic indicated the OEM one "looked bad" last time it was changed. Gotta take care of that baby too!

I did try to find a SERVICE on Long Island who would come to the boat and do fuel polishing with a mobile unit. Google and dockmasters failed me. Could not find one!

There are some interesting Youtube videos if you search on fuel polishing at that site.

Good luck.
 
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Polishing will not make 3 year old diesel new. The diesel of today is a complex bit of chemistry and modern engines are picky about fuel - such as cetane level. It would be best to start with fresh fuel. You can probably sell the old to a fishermen who’s low tech engine will burn anything.
 
Take a look at this site for great info on making a polishing system.

You do want to pull from the crossover because it is at the bottom of the tank.

Also, we have done a loop and a half and got some bad fuel in Maryland somewhere. Here is a pic of what came out of my pick up when I pulled the hose.
IMG_2525.jpg

A Seatow captain told me about AJX and I ordered two bottles because I could not find a company to polish the tanks for 2 weeks.
You wait 72 hours after putting it in your tank and it kills and then dissolves any bacteria in the fuel or on the sides. It worked for me and I did not have to polish the fuel. No more soot either. I do not have any affiliation with the product.
 
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Much of what the Diesel Dipper director says is accurate, however, I'd question aspects of the data he shares. Some of it sounds a bit scare mongerish.

The "Diesel Dipper's" clear plastic bowl lacks ABYC compliance if it is installed in an engine room, it has no heat shield for flame resistance.

In my experience, no additive can clean a fouled fuel tank, so please don't fall for advertising hype regarding tank cleaning in a can, it's simply not possible (he didn't say it could, but others often do).

50% is not a universal fuel return number, it varies from engine to engine. Also, the notion that primary and secondary filters are actually polishers is simply not true. Many recreational marine engines sit idle for weeks or months, during which time they aren't "polishing". Also, the volume at which an engine pumps and filters fuel is a fraction of what a true polishing system will, polishing system pumps can be 100 GPH or more, for as long as you run them, and they can be run dockside, or while underway. A polishing system's high volume pump will create a current across the bottom of a tank, which will entrain contaminants, and trap them in the filter, provided it is plumbed with pick up and returns to the bottom of each end of the tank. Alternatively, picking up from a well in the tank bottom is also effective, but return fuel should not splash from the top of the tank, returns should have drop tubes. Splashing fuel aerates it, which hastens its degradation.

A polishing system, any polishing system, that includes a bottom of tank pick up, will remove water.

Crude oil has come from all over the world, not just Brent, for ever. He is right, sweet crude contains less sulfur.

The biodiesel that is added to diesel is not "MacDonalds" deep fryer oil, and rarely animal fat based, it is almost all FAME, or plant-based. Biodiesel has a higher lubricity than distillate-diesel (mineral based diesel fuel) and higher cetane, it's often added in small amounts, 1-2%, to diesel after removal of sulfur, to replace the lost lubricity. In that small amount, it has no meaningful effect on diesel's longevity. In higher percentages, 5% and above, it can and does affect diesel's tank life. More on bio-diesel here https://stevedmarineconsulting.com/wp-content/uploads/2014/03/BiodieselProBoat116.pdf

Asphaltene is not a 'modern diesel problem', it's been an issue for decades, certainly as long as I've been in the business, 35 years.

You only can have "diesel bugs", bacteria, if water is present. Without water, no bugs and no need for a biocide.

Condensation inside tanks is mostly myth, I've looked inside scores of diesel tanks all over the world, in all weather conditions, and have never seen visible condensation other than in a tank whose inspection ports were removed, allowing warm humid air to enter a cold tank.

If you fill a tank to the top, it's likely to overflow on the first warm day, BTW. So, 9/10 is better if you are going to "fill" it for storage.

"Rubish diesel"? The primary and secondary filter should prevent this from making its way to the engine. They may get clogged, but they should not allow dirty fuel to pass.

The dip tube is a great idea, makes great sense, it's been called a stripper tube for a very long time, detailed here https://stevedmarineconsulting.com/cleaning-diesel-tanks/ This tube is really what's different, any filter/pump picking up from the bottom of the tank will remove water, without this device.

How does one drill holes for the tapping screws flange without filings going into the tank? I would not rely on tapping screws for a tank fitting in any event, they should be threaded machine screws.

Diesel fuel sold in the US, for on road, off road and marine applications, must meet ASTM D-975-21 (and EN-590 in the EU). You often hear additive manufacturers warn users about low quality or otherwise flawed diesel that needs an additive in order to run safely in your engine. While off spec diesel does exist, most of it is on spec and compliant with D975. Tens of thousands of over the road trucks run tens of millions of miles with straight ASTM spec diesel. To say it has changed dramatically in recent years simply isn't true. Yes, sulfur content has been substantially lowered over the past 20 years and that has had some side effects, however, it is being implied in this video that it lasts no longer than gasoline (6 months, that may be what fuel refiners say, but they have a vested interest in you using fuel, or disposing of it because it is "old"), and that's simply not true, diesel is far more stable.

More on additives https://stevedmarineconsulting.com/diesel-fuel-additives-part-i/

I primarily use two additives, Stanadyne Performance Formula to improve cetane and lubricity, and Gold Eagle StaBil when storing diesel and gasoline.
 
I've been buying diesel for my own boat since 1963 and using diesel on other boats before that. The diesel has changed for the worse. It was once formulated for stability and good combustion efficiency, but no longer. It's now formulated to suit political views. Among other things, new fuel doesn't have the same cetane rating, lubricity, or stabilizing additives. When I was young, before the EPA, I never used additives. I didn't need to.

I've run many engines of the same brand and compare their power and efficiency over 60 years of running. And the fuel doesn't give the same results unless I use an additive.
The black slime on tanks is organics and their waste. If you use a good biocide you kill the slime and it eventually falls to the tank bottom to be caught in the filters. I've done that many times on many boats and ships. I use to work bringing mothballed ships back to life. Some sitting more that 20 years. Growing bugs all the time. Using a strong biocide, usually 3x or more, kills the bugs and then it's just a filtering job. I never saw a need for someone to enter a tank to clean bug residue.
 
Nothing to do with polishing, but expanding on Lepke'sRV quality of diesel. My cuz is annal about monitoring his engine in a 40' diesel pusher RV. Since Calif implemented their "15% cleaner" diesel he has found he gets 15% worse fuel mileage than when he goes to Az and uses the old formula. So the 15% cleaner Calif diesel requires you use 15% more diesel to get to the same place, therefore absolutely no improvement but of course, extra costs.
 
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