# Cleaning Out a Diesel Tank



## Allanbc (Apr 19, 2007)

What is the best way of cleaning out a diesel tank on a used boat?


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## RichH (Jul 10, 2000)

*If you have proper 'access' ports on the tank ....*

Drain tank and take old oil home to burn in your oil heater.

Long handled scrub brush to knock the agglomerated particulate from the tank walls ..... sop up residue from tank bottom with paper towels, then burn !!!!!! 
Then pressure washer, and pump the water/oil waste to a 55 gallon drum and let it gravimetrically stratify .... soak-up the oil that eventually floats on top of the oil/water mix with paper towel s (let the towels 'dry' then burn the towels) or use 'bilge boom' absorbant pillows (polypropylene fibers/matting rolled up into 'log) & discard at a recycle center (or burn). 
Then ..... when the tank is visually clean, add a few gallons of NEW fuel and recirculate through a polishing filter @ 1uM rating (many times through the SAME filter).

If you dont mechanically remove the 'crud' from the tank walls first, all the subequent filtering/polishing will be very inefficient. You have to get the 'crud' off the tank walls FIRST.

Hope this helps.


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## hellosailor (Apr 11, 2006)

Allan, because of access problems it often is easier & more effective to remove the tank from the boat. Then it can be cleaned out more thoroughly.

There's at least one long discussion about this either on this forum, or on Cruisers & Sailing Forums.


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## Gene T (May 23, 2006)

The method stated is indeed the best method, if the tank is removable. Often it is not. Then one looks for alternatives. 

Check if your area has a fuel polishing service. They drive over in a boat equipped with pumps and filters. Cost varies depending on access or what they have to do to get their wand into the tank. There is a crud that builds up on the bottom of the tank from dead algae that needs to be broken loose, pumped out and filtered. The clean fuel is then pumped back into your tank. Once it is scraped clean they will keep recycling the fuel until it is clean. Process works good if the person knows what they are doing. 

I did this myself rather than paying someone else to do it. My problem started when the pick up tube in the tank was plugged by some loose crud. I removed the fuel gage sender which happened to be over the lowest part in the tank, good thing because this is where the crud is. I scraped the bottom with a copper tube as I pumped the fuel through it and into a makeshift filter made out of old t-shirts and gallon plastic jugs. Once filtered I poured the clean fuel back into the tank. I used an outboard bulb pump which worked fine, just tiresome and slow. This is somewhat dangerous, very messy, smelly and pretty unpleasant. It was however dirt cheap. 

My engine was set up with 2 in-line filters, a Racor and the one that is mounted on the engine. I used a 30micron for the Racor primary. After this process I had no problems more problems, 5 years then sold the boat. 

Now that I have had the experience I would hire it done.


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## mpraca (May 12, 2001)

One alternative that will give you long term reliability is to install a bypass valve and a pump that will recirculate your fuel through the filter while the motor is not in use. Just leave it running for a few hours and check the filter if it needs replacement. That's cheaper than removing a tank and will get you out of trouble if you ever get contaminated fuel.


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## RichH (Jul 10, 2000)

Sorry to disagree but a recirculation polishing system will not remove tank wall accumulated debris. It will only remove debris that is in 'suspension' in the fluid/oil. 
A recirculation system will tend to keep the particles from adhering to walls as it removes them quickly upon their formation (as agglomerates of hard had 'soft' particles). 

Dont waste time and money with a recirculation polishing system without FIRST mechanically cleaning the tank.


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## sailingdog (Mar 19, 2006)

Biodiesel is said to have an effect of dissolving much of the crud in a diesel tank, so loading up with a batch of biodiesel or biodiesel/diesel mix and letting it circulate, via fuel polisher might do the trick.


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## Boasun (Feb 10, 2007)

After you pumped the tank empty. Pressure wash with a solvent to clean the tank and then strip the residue into 55 gl drums and have an eviomental company cart it away.
Here in the southland, I had to have it done to a vessel I was working aboard. Pumped off 12,000 gl to a tank truck. Pressured washed the tanks then filtered the fuel as we brought it back aboard. The reason why? We went through a case of Racor filters in about 9 days, and as we was going back off shore the engines started losing power. Turned the boat around and refused to take it out until they clean the fuel tanks. After that was done, we changed racors about every two months or so. 
Lesson? Pays to clean your tanks, especially if they had set for awhile.
You should have seen the crap we got out of the those fuel tanks and fuel lines. Don't forget to clean the fuel lines also.


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## Giulietta (Nov 14, 2006)

OK...simple way...

Open fuel cap, its dark inside, so light up a match to see better inside and approach it......


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## Allanbc (Apr 19, 2007)

Giulietta said:


> OK...simple way...
> 
> Open fuel cap, its dark inside, so light up a match to see better inside and approach it......


I hear that works better if you have gasoline rather than diesel.  Would you care to come and demonstrate that method? 

Thanks to all the rest of you for the tips!


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## TSOJOURNER (Dec 16, 1999)

Giulietta said:


> OK...simple way...
> 
> Open fuel cap, its dark inside, so light up a match to see better inside and approach it......


Better way, you could use fertilizer to soak up the diesel. Insert a fuse. It would probably clean out half your marina.


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## SimonV (Jul 6, 2006)

CapnHand said:


> Better way, you could use *fertilizer* to soak up the *diesel*. Insert a *fuse*. It would probably clean out half your marina.


Oh O, I think sailnet has just been flagged on the FBI computers them words in the same sentence.


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## sailingdog (Mar 19, 2006)

That would mean that CapnHand has been flagged as a person of interest..


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## hellosailor (Apr 11, 2006)

What, you didn't hear the rumour that DHS was spnsoring this whole web site, so they could keep an ear on boating traffic? < WEG >

Seriously, now they're trying to float a plan that would have all small craft equipped with transponders, to make sure we're not sneaking terrorists around the harbors. I wonder if anyone ever told the Secretary of Homeland Insecurity that anything electrical just isn't all that reliable on small craft...


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## Boasun (Feb 10, 2007)

Transponders on boats??? Oh Me! Oh My!
Its happening. AIS, Automated Identifying System. Now being put on all commerical vessels. And some yachts are putting it on board also. Great when tied into your radar along with your GPS. You can now see where the other vessels are at night or in restricted visibility.
Yes the USCG knows where you are, but you know where everyone who has transponding AIS is at also. This should really help in reducing collisions at sea, the rivers and in the harbors. But you still don't know where the vessels that don't have AIS are at??
This is one of those tools that can help you be safe out there. But then makes it harder for you to hide from the authorities, unless you turn it off. But it does have a "Pirate Panic Button" on some models. And in some areas of this world you still need it.


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## hellosailor (Apr 11, 2006)

Well, ignoring the fact that the USCG in the Port of Miami has been doing heavy testing with AIS and tracking...and publicly stated that basically they are overwhelmed almost all the time and find it nearly useless?

Yeah, right, you try telling every kid with a SkiDoo to install AIS on it, and then figure out a way to maintain it in operation.

It makes me think we'll all need to buy surplus weather balloons (aka The Prisoner) stick transponder in 'em, and them have a protest "float".

Or better yet, fly to the nearest jihadi and stick an AIS in HIM. this business of flagging all the sheep in order to watch the wolves, gets old fast.


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## sailhog (Dec 11, 2006)

Why don't sailboat fuel tanks have sump drains a la aircraft fuel tanks? It wouldn't solve the algae and water problem, but it would go a long way in doing so.


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## hellosailor (Apr 11, 2006)

"Why don't sailboat fuel tanks have sump drains "
Depending on who you ask, it is a USCG regulation, or an ABYC regulation, or an insurance thing. Someone doesn't want to take any chance on your dumping 50 gallons of explosive fuel into the bilge, no matter how well you think the tank drain is secured.


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## sailingdog (Mar 19, 2006)

Some custom-built tanks do have a sump area and a sump pickup tube, but that's fairly rare in production boats.


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## TSOJOURNER (Dec 16, 1999)

The drains you see on the lower surfaces of aircraft wing/fuselage fuel tanks and lower parts of the engines are primarily to remove water prior to starting and take off. Water is heavier than fuel and could ice the system causing a shutdown. Depending on the size of the aircraft, large "defuel valves" are installed you use to connect drain hoses and defuel the aircraft using the onboard pumps. 

Jet fuel is a little better grade than diesel and suffers the same biological growth problems. An additive called "Prist" is added to jet fuel either in the ground tank or by spray bottle and introduced while fueling to prevent the biological contamination that occurs in untreated jet fuel and to prevent icing at altitude. 

I have to clean my diesel tank and am following this thread to learn the best way to do it. I will be using Prist or a similar additive with every fueling there after.

Wish I had a defuel valve and an access panel!


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## bwindrope (Feb 25, 2007)

*My system on Aeolus*

On Aeolus I do a few things to reduce fuel problems. For one, I run a biodiesel blend of about 50% for purely mechanical as well as environmental reasons. No doubt about it, biodiesel does act as a detergent and cleans things out. My diesel Mercedes is the same deal. Had to replace a few filters after the first few tank fulls, and now no problems.

Anyway, Aeolus has a Racor primary and standard engine mounted secondary. I run a 2 micron primary filter because the filtration capacity is something like 30gph and my Universal M40 only uses 1 gph. I want that Racor to keep anything from even making it to my secondary.

My "polishing" system is to get back from a nice bouncy sail, tie to the dock, go below, disconnect my fuel return from the engine and connect it to my electric fuel pump "out". This way, the fuel pump is pulling fuel through the Racor, and pushing it right back into the tank through the return line. I do this once or twice a season and just leave the ignition key on and let the pump do its thing for 20 minutes or so. I measured once and found this amount of time would circulate more than double the tank capacity.

I know this is less thorough than removing the tank and so forth, but Gulf 32's have 70 gallon diesel tanks that are integral to the hull. They do not come out without major surgery.

I have never once had a fuel related engine problem. She runs smooth like silk and I think my filtration and "polishing" are a big help.

Good luck and best wishes,


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## JiffyLube (Jan 25, 2008)

The easiest way I think is to hire a company that cleans tanks out with a wand (if you have an access port), and polishes the fuel. I had that done on the boat we own after we first bought it, and it cost about $200.00.


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## MedSailor (Mar 30, 2008)

*Bilge Yoga....*

I timely topic for me. Today I was pumping nasty fuel out of my tank and hauling it up to the marina oil recycling barrel. My fuel is about 3 years old, there is known to be a gallon or so of water in the 90 gal fuel tank and there is DEFINATELY algae.

I have great tank access so it limits the necessity of bilge yoga, but I have no access ports. My plan for the tank is to pump out all the fuel. Add 10-20 gals of water, pump it out. Then add 10 more gallons of water (to further reduce the chance of fire) and cut some inspection ports into the top of the tank using a stainless cutting bit on a dremmel tool. Once I have inspection ports I'll scrub it out as best I can, dry it well, add some new clean #2/bio mix and biocide and watch my filters. I also installed a vacuum guage on the racor so maybe I'll have a little warning before she shuts down.

I'm half way through emptying the tank and even though I wasn't at the lowest spot on the tank I got a couple softball sized balls of creepy crud from the bottom along with 2 liters of water.

Owning boats is fun...... 

MedSailor


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## sailingdog (Mar 19, 2006)

Instead of adding water to the tank, IMHO, you'd be better off adding nitrogen or CO2 to the tank. That will force out the oxygen and leave a layer of relatively inert gas over any remaining diesel fumes or fuel. It's also a lot easier to clean up after.


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## MedSailor (Mar 30, 2008)

sailingdog said:


> Instead of adding water to the tank, IMHO, you'd be better off adding nitrogen or CO2 to the tank. That will force out the oxygen and leave a layer of relatively inert gas over any remaining diesel fumes or fuel. It's also a lot easier to clean up after.


NICE IDEA!!!!! Now, I'll just put my mouth over the fuel vent and continue to breathe until it has a high Co2 concentration. 

MedSailor


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## hellosailor (Apr 11, 2006)

If you have no handy cheap CO2 source, throw in some dry ice and come back after lunch.<G>

In some southern states the supermarkets sell it for fishermen and coolers. Ice cream trucks & suppliers sometimes have it. Or your local yellowpages, somewhere it can be found, fairly cheap. (If all else fails, you order a box of Omaha Steaks and use the dry ice they ship with.<G>)


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## sailingdog (Mar 19, 2006)

Drop a chunk of dry ice into the tank... That's work much better IMHO....

your way introduces too much hot air into the tank. 


MedSailor said:


> NICE IDEA!!!!! Now, I'll just put my mouth over the fuel vent and continue to breathe until it has a high Co2 concentration.
> 
> MedSailor


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## MedSailor (Mar 30, 2008)

*Letters from the bilge....*

I spent the entire day in the bilge. I tell you if I really liked sailing I would belong to that club on the next dock.

Each time I would get disheartened with my project (as a pump died or such) I would suck up another softball sized ball of goop and another liter of water from my half-full 90 gal tank. I swear one of the balls of goop had eyes and even gave me the finger!  Shortly after that I opened more hatches for better ventilation...

The tank is now as empty as I could get it and I can see through the existing 3" hole in the top that all the walls of the tank are lined with algae. I can't wait to get in there and kill them all! Next I must cut inspection port holes into the tank and fashion port covers.

Any suggestions on what will cut through 1/8" stainless? I was planning on using a large dremmel tool with a tungsten carbide bit, but I've never tried this before. I could also use a jigsaw or reciprocating saw with metal cutting blades but I can't imagine this will be pretty.

As for the inspection plate cover my resourceful neighbor suggested using polyethylene as it is much easier to work than stainless. Perhaps a couple dollar store cutting boards cut to size? I would then drill and tap machine screws to hold the plate down.

As for a gasket, I'm not sure here. My fuel gauge (which has a 3" hole) has a rubber looking gasket but I'm not sure what it's made out of. Anyone know what's a good gasket material and is impervious to diesel?

Thanks again for the dry ice suggestion.... Going to hunt some down tomorrow.

MedSailor


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## sailingdog (Mar 19, 2006)

There are quite a few RTV silicone compounds that will work for a fuel tank inspection port gasket. As for the inspection port itself, I would try and find a bronze or stainless steel deck plate and ring and use that. Through bolt it to the tank, using the plate opening to give you access to the underside of the opening. 

BTW, make sure you clean the tank very, very thoroughly when you're done. Metal shavings and bits, such as are left over from drilling and cutting stainless steel are bad for your engine.


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## hellosailor (Apr 11, 2006)

Med, I'd discourage cutting holes because each hole means shavings and metal bits that may work into or past a filter, no matter how careful you are. And someplace to leak when you fill it, no matter how careful you are. I do't think any RTV or silicone compounds are rated for 100% contact with fuels, as they will be in a tank. You're looking at mechanical clamps or welding and rings and hatches to proeprly recover each of the holes you make--more more work.

I'd get hold of a steam genny (generator) even one of the "home" grade ones if that's all you can get. Steam the algae off, or fill the tank with algecide and soapy water, and try to wash out or mechanically remove as much as you can, before you turn to making holes.

If the tank can be removed form the boat--do it that way. If that means lots of work to get it out--that's still going to be a better idea than making lots of holes the hard way.

if the tank is OUT you can do things like wash it, rinse it, pressure hose it, rinse out any shavings from metal work, etc. If the tank is left in place--you just don't have those great options.


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## artbyjody (Jan 4, 2008)

I would offer a different suggestion....

The one issue that gas versus diesel boats has is the issue of varnish / algae.

There are plenty of diesel gasket materials (as for gas) that you can get at NAPA - to do such larger inspection / washout ports... Unless you are a constant motor-sailor this is a real issue. 

Having known my Atomic 4 damage was a result of varnish... and now going to own a diesel with even less run times.. it is more prudent to do what you can to clear the problem on a visual inspection versus wondering what to do and $$ after it occurs... inspection windows that couple as access ports - priceless...


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## sailingdog (Mar 19, 2006)

Jody-

Diesel doesn't form varnishes or gum up AFAIK. The biggest problem with diesel is bacterial slime growth at the water/diesel interface.


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## artbyjody (Jan 4, 2008)

sailingdog said:


> Jody-
> 
> Diesel doesn't form varnishes or gum up AFAIK. The biggest problem with diesel is bacterial slime growth at the water/diesel interface.


Duh I stated that SD... that is what varnish / algae denotes (the slash)...my english is bad tho I forgive.. been getting lessons from a Portuguese...


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## hellosailor (Apr 11, 2006)

Gasoline is a witches brew of often up to SIXTY fractions and components, including things like heptane and butane which literally boil out of it within days or weeks. So varnish doesn't form, so much as it simply "Drops out of suspension" as the lower fractions gel out while the higher ones evaporate. It may or may not all be the same (I won't argue that one[g]) but it certainly isn't all made the same.

"Pump" fuel, diesel or gasoline, is typically designed to be fairly stable for 60-90 days from the date of manufacture, and whether you use gas or diesel you will have problems with "stale" fuel. Depending on the storage, the oxidation, the condensation, the temperature...you will have problems, usually around the six month point. For many of us, who think the "iron genny" is a god best worshipped infrequently, that can mean a good part of the fuel in this year's tank is last year's fuel, and tossing in a couple of bucks worth of biocide/stabilant is a terribly inexpensive precaution to take if you're not "driving the bus" and burning that old fuel out on a regular basis.


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## SimonV (Jul 6, 2006)

hellosailor said:


> Gasoline is a witches brew of often up to SIXTY fractions and components, including things like heptane and butane which literally boil out of it within days or weeks. So varnish doesn't form, so much as it simply "Drops out of suspension" as the lower fractions gel out while the higher ones evaporate. It may or may not all be the same (I won't argue that one[g]) but it certainly isn't all made the same.
> 
> "Pump" fuel, diesel or gasoline, is typically designed to be fairly stable for 60-90 days from the date of manufacture, and whether you use gas or diesel you will have problems with "stale" fuel. Depending on the storage, the oxidation, the condensation, the temperature...you will have problems, usually around the six month point. For many of us, who think the "iron genny" is a god best worshipped infrequently, that can mean a good part of the fuel in this year's tank is last year's fuel, and tossing in a couple of bucks worth of biocide/stabilant is a terribly inexpensive precaution to take if you're not "driving the bus" and burning that old fuel out on a regular basis.


Please explain? I have about 40gal of Diesel in the tank and will be adding 40gal more; I have no access ports into the tank. I have 8 new fuel filters on standby; I leave for a long trip off shore what should I add to the fuel????


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## sailingdog (Mar 19, 2006)

HS--

The more recent ethanol blends of gasoline have noticeably shorter shelf-life than the older MTBE-based gasolines. This is because the ethanol will come out of solution with the gasoline once the water content of the mixture reaches 1.5% or so. This will leave you with a layer of contaminated "alcohol" and a layer of gasoline that is roughy 82 octane or so.


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## TSOJOURNER (Dec 16, 1999)

On my old Catalina 30, I was able to remove the tank and I went to a self car wash and blasted that puppy clean. 
If you cant remove, then RichH is right. If you cant scrub the tank of all crud, then its useless to just clean and change fuel.


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## hellosailor (Apr 11, 2006)

Simon-
Any chandlery or auto supply store will have a rack of "fuel treatment" bottles from different makers. And any brand name product should work reasonably well. They contain additives designed to make the fuel (gas or diesel, whichever they are for) more stable for long-term storage. For diesel they will include a biocide to keep critters from growing, and probably a cetane booster because diesel loses power as it ages, and I'm not sure what else. For gasoline, the additives are designed to keep things in suspension, and prevent/compensate for the evaporation of high end fractions. Exactly what each one is and what it claims to do, is not my department.[g] But for fuel that will be STORED unused for long periods (i.e. 6-12 months or longer) they all seem to make a big difference in how well that fuel burns and how it causes fewer problems.

If you are going offshore with the intent that your fuel may be stored and unused for over 3 months, pick a brand name that you recognize (one of the petroluem companies or chemical makers as you please) and use the product according to the directions. With no access ports you are limited as to being able to inspect or clean, all you can do is hope you've got enough filters and the tank itself is clean to start with.

Personally I think anyone who builds a marine tank without inspection access ports should be keel-hauled, the old fashioned way without antibiotics on a fouled bottom. And having heard a "reliable" diesel sputter and die once too often, I no longer trust the fuel from ANY pump, I want to see it pumped through a "baja filter" or other filter strainer which absorbs moisture and dirt, and lets me watch what is coming in with the fuel.

But that's just me--I hate bleeding diesel fuel lines, I hate the smell of diesel, I have zero tolerance for anything "diesel" that is less than 110% reliable. I'd rather wait for the seasons to change and a breeze to come up.[vbg]

SD-
Ethanol. Gasahol. I can't wait for the history books to finally write about the greatest agrobusiness boondoggle of the 21st century! Good point, the ethanol can be problematic, as much as the changeover to lead-free fuel was. I want gasoline in my gasoline, not vodka! Aside from the damage it can do, I can't think of any reason for it unless you own Archer-Daniels-Midland stock, because whatever it gains, it immediately loses since you need to burn 10% more of it to make up for the lower energy content. And for this I pay taxes?!


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## MedSailor (Mar 30, 2008)

hellosailor said:


> Personally I think anyone who builds a marine tank without inspection access ports should be keel-hauled, the old fashioned way without antibiotics on a fouled bottom. And having heard a "reliable" diesel sputter and die once too often, I no longer trust the fuel from ANY pump, I want to see it pumped through a "baja filter" or other filter strainer which absorbs moisture and dirt, and lets me watch what is coming in with the fuel.
> 
> But that's just me--I hate bleeding diesel fuel lines, I hate the smell of diesel, I have zero tolerance for anything "diesel" that is less than 110% reliable. I'd rather wait for the seasons to change and a breeze to come up.[vbg]


AMEN BROTHER!!!! This all started because I was having a *%&^!! of a time bleeding my engine and I decided that I plan to own this boat for a long time and I want to do it right and do it as few times as possible.

I appreciate the suggestion not to cut holes, but I really do want inspection ports. If I start consuming filters years from now after taking on dodgy fuel in Tarawaga-nonga I want to be able to see what's living in my tank. I'm not really worried about metal shavings as I'm sure I can remove most all of them and the ones I can't are likely to be spun out by the Racor and if not they should be larger than 10microns and caught by the filter paper. Besides with a shiny clean tank I have to have SOMETHING for my Racor to do.

I made a pilgrimage to one of the only good hardware stores left in the Seattle area. They talked me into a high-carbon 5" hole saw. An expensive tool but any engine work is expensive.... I'll report tomorrow on how it goes.

SimonV. Please DO NOT PUT BIOCIDE IN YOUR TANK! I wouldn't put any additives in your tank if your engine is running well. If your fuel is really old you can add "cetane" (diesel's equivalent of octane) which degrades with time.

If you've never added biocide before you "may" have algae in your fuel and it "may" increase the rate of filter usage but I guarantee you that if you do have algae and you put biocide in there you will suddenly have a HUGE clump of algae that will cause big problems.

To give you an example when I bought my first boat I had a 7 gal tank for the heater and a 55gal tank for the engine. I heard about algae and decided to try the additive in the 7gal tank first. The next day I had about 1.5 cups full of coffee ground like dead algae in the bottom of the tank. Clogged up the 1/4 inch fuel line and was a huge headache. I decided not to add any to the large tank. I motored that boat quite a bit over the next 6 years and only changed the filters once (preventative). Yes there was some visible growth in the bowl and I'm sure there was some in the tank but it was doing me less harm clinging to to sides of the tank than all dying and clogging up my lines and filters at once. Tank access in the old boat would involve cutting the boat in half.

MedSailor


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## SimonV (Jul 6, 2006)

Medsailor
Thanks for the reply, but your advice on the algaecide flies in the face of the majority consensus. Now I am more confused, as your advice seems to have merit.


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## MedSailor (Mar 30, 2008)

SimonV said:


> Medsailor
> Thanks for the reply, but your advice on the algaecide flies in the face of the majority consensus. Now I am more confused, as your advice seems to have merit.


I can appreciate that my advice may seem to fly into the face of conventional wisdom, and it might. I've been wrong before.... once, in China.  My experience is based on advice given to me by experienced boaters and only one experiment so YMMV. I'd just hate to have you make a big mistake though.

I'd hope that you would think seriously about these two things, which I try and make as a cornerstone of all my medical decision making: 1. If it ain't broke, don't fix it. 2. Do the likely benefits of the intervention more than slightly outweigh the possible consequences of the intervention?

So now that I've hopefully seeded appropriate conservatism I'll play the other side. The critters which might inhabit your tank live in two places in my limited experience. They live in the interface between the water and the diesel and they live clinging to the walls of the tank. Most folks smarter than myself don't keep water in their diesel tank so they're on the walls. They tend to stay there for the most part in cold climates, hence my ability to use my last boat for years and years without issue.

The problem crops up if you go offshore or get in a really stinky choppy sea. Significant boat and or wave action, especially in a partially full tank can cause the critters to get all stirred up and float free where they can get sucked up in your intake and clog your filters. Though not in any really dramatic way and if you have spare filters, and the ability to change them you should be fine.

Now I'm not trying to confuse you, just give you as much information as possible so that you can make your own choice. If you're about to go offshore tomorrow and have no known fuel contamination or water in the fuel than why mess with a good thing? On the other hand if you have handy inspection ports (in case things go badly) and are going to be dockside for a while why not try adding the poison and see what happens.

One option that may help you is to enter the tank through the pickup, vent, fill, inspection port or wherever you can and pump out a gallon or so from the bottom of the tank. Put the fuel into a clear plastic container and allow it to settle. Is there water on the bottom? Are there coffee grounds in it? Can you easially see light through it or does it hinder light like a good hefeweizen? This won't tell you what's clinging to your walls but it will give you an idea of how clean your fuel is.

Hope I helped and didn't confuse you too much.

MedSailor


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## sailingdog (Mar 19, 2006)

Simon-

Just keep the water out of the tank, and the biocide won't be necessary. The algae/slime can't grow without the water.


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## camaraderie (May 22, 2002)

Simon...I have a bit different take on all this for YOUR situation. You have bought an older boat with fuel that has been in the tanks for quite a while. One may assume that there is both a significant amount of water AND algae growth in that tank. You also have no access to that tank...and when you go offshore and get in heavy weather with the engine all that crap will get stirred up and stop you cold...again and again after filter changes...to say nothing of the danger a failed engine might put you in, in some places. 

There are only two solutions to your probelm. One is to cut access ports and clean out the tanks yourself. The other is to call in a good fuel polishing service that has the ability and competence not to just suck fuel out of your tank but also to keep moving the lines around to stir things up and remove the settled debris. In my opinion...one of these options is a MUST before embarking on a journey like yours. 

I agree with MedSailor on the use of biocides in a dirty tank...they will just compound the problem. Biocides should be used to PREVENT algae growth rather than CURE it. That perhaps is where the conflict between advice exists. Biocide is GOOD...and some fuel brands add it at the pump in the USA...but because it kills algae, you can wind up with a mess in your tanks if the algae is already there as MedS says. 

I am in total agreement with HS on the need for access ports on tanks. I think a balanced view of the danger posted by ports for diesel tanks vs. the danger posed by engine failure would argue that ports are a good thing.


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## TSOJOURNER (Dec 16, 1999)

I hired a man last year that pumped everything out, pressure washed the inside walls, pumped some more, pressure washed and pumped again....
he had HUGE Racor type filters and then pumped clean fuel back in..... you sould actually see the dirty fuel pumped out and the clean fuel being pumped in..... haven't had a problem since and will probably do it again this year......

let's face it, fuel is probably the #1 problem on boats.....
well, maybe running out of RUM is right up there, too!


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## hellosailor (Apr 11, 2006)

Med-
IIRC I've been told to use heavy grease on the saw blades to trap any shavings or dust, so it can be wiped off later rather than just blowing it around.

Simon-
The duality of algecide seems to be that if you use it, it will killl algae which will drop out on the tank, creating sludge in the tank. But if you don't use it--they'll grow anyway, eventually die and turn to sludge (ust not all at once), and wind up in your filter instead of your tank.

Seems that the only question is where you want their little bodies, and how many the shock of the algecide is likely to cause. If your tank is clean before you start, of course there won't be many bodies to form sludge in the first place.

But if you put some snails or small catfish in the tank, to eat the algae...[g]


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## JiffyLube (Jan 25, 2008)

bfdtpkt said:


> I hired a man last year that pumped everything out, pressure washed the inside walls, pumped some more, pressure washed and pumped again....
> he had HUGE Racor type filters and then pumped clean fuel back in..... you sould actually see the dirty fuel pumped out and the clean fuel being pumped in..... haven't had a problem since and will probably do it again this year......
> 
> let's face it, fuel is probably the #1 problem on boats.....
> well, maybe running out of RUM is right up there, too!


I agree with you, that's the easiest way to solve this problem.


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## SimonV (Jul 6, 2006)

I will look into having the fuel polished, the only access I have is through the pick up, fill pipe or the fuel gauge opening. Holding just under 40gal of 80.
Can anyone recommend an operator in the San Francisco area.


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## JiffyLube (Jan 25, 2008)

SimonV said:


> I will look into having the fuel polished, the only access I have is through the pick up, fill pipe or the fuel gauge opening. Holding just under 40gal of 80.
> Can anyone recommend an operator in the San Francisco area.


I used a company called Marine Lube while our boat was at Marina Village, and it costs $250.00 (found the receipt) to wand and polish. They were recommended to me by Don Wilson (boat broker), at Tartan C&C in Alameda. All the recommedations I got from Don turned out good, as they all do work for Tartan C&C. Don Wilson is well known in your area, and was a great help to me.


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## bzalto (Sep 15, 2008)

That bit of humor made the day!


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## MobiusALilBitTwisted (Jun 25, 2007)

4 years dead, Now Look at it.


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## UncleJim (Jul 27, 2009)

MobiusALilBitTwisted said:


> 4 years dead, Now Look at it.


Good threads never die, they just leave you hanging. 
...did Medsailor get his inspection hole cut?
...did SimonV get offshore without dead critters in his tank?
...and what about taking two very large dogs cruising on a sailboat? oh wrong thread my bad


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## MedSailor (Mar 30, 2008)

UncleJim said:


> Good threads never die, they just leave you hanging.
> ...did Medsailor get his inspection hole cut?
> ...did SimonV get offshore without dead critters in his tank?
> ...and what about taking two very large dogs cruising on a sailboat? oh wrong thread my bad


YES! Inspection holes cut! Tank is spiffy clean! Nobody was immolated and S/V (or is it M/V?) Fairhaven has put a couple hundred hours on the same Racor filter now. Life is good with a clean diesel tank. You should have seen the fistfuls of crud I pulled out.

MedSailor


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