Cleaning out diesel tank?

petersea · Apr 20, 2010

The filters did exactly what there were supposed to do.....get out the junk. You may need to have your fuel "polished" and tank clean but with out physically looking you will not know for sure. If you boat is 15 to 20 years old with the original tank good bet you will need to clean it. It is not a cheap job and sometimes it is almost as cost effective to replace the tank if you can do it yourself. I would put new filters on run it 10 hours and replace filters again. Inspect old filter to see what if there are clogging up also. You should run a bio-cide type fuel treatment in your tank year round. If you need the tank cleaned there are service that specialize it just that thing as well as polishing the fuel. It is also a do it yourself job for anyone who is mechanical inclined and willing..........

s sauer · Apr 20, 2010

Access Port

A more effective option is to remove the fuel line from the tank at the Raycor filter and use a hand pump to remove all fuel to fuel can(s). Then cut open a 4" or 6" hole in the top center of the tank and install a Seabuilt access panel (about $145). Mop out the remaing gunk and poly or metal shavings from cutting the hole, and swab the inside of the tank with alcohol and clean rags; wipe or spray down the fuel gauge components and clear the end of the fuel intake line. Again final clean / wipe down with alcohol and clean rags before refilling with new clean diesel. Replace the fuel line from the tank to the Raycor if it is OEM, replace all filters and bleed the lines before starting the engine.
In my opinion, this is the only real way to know what's clean and to check again every so often for peace of mind. Fuel polishing leraves you not knowing if anything is still sticking to the walls or top of the inside of the tank.

sailaway78 · Apr 21, 2010

Firstthings first

The first question to ask is how long has the filter been in there. If it was changed a few days ago, you have a problem. If the filter has been in there ten years, change it and forget about it. Sooner or later, every filter is going to get clogged with trash, if left in long enough, thats what it is suppoed to do, collect all the trash in the fuel.

larryw · Apr 21, 2010

All good advice; For a quick-and-dirty, you could also remove the pick-up tube from the tank, cut off the bottom 1 in. and re-install. This raises the pick-up point further from the bottom of the tank, but remember, you will effectively have a little less fuel capacity, so keep the tank somewhat more full.

Bob S · Apr 21, 2010

I am planning on cleaning my tank before launching this year.

If you cut a 4-6" access hole can you use a piece of Lexan polycarbonate to make a cover? Will it stand up to diesel fuel? I was going to cut a piece of neoprene rubber as a gasket.

Comments would be helpful.

catsailor · Apr 21, 2010

petersea said:
The filters did exactly what there were supposed to do.....get out the junk. You may need to have your fuel "polished" and tank clean but with out physically looking you will not know for sure. If you boat is 15 to 20 years old with the original tank good bet you will need to clean it. It is not a cheap job and sometimes it is almost as cost effective to replace the tank if you can do it yourself. I would put new filters on run it 10 hours and replace filters again. Inspect old filter to see what if there are clogging up also. You should run a bio-cide type fuel treatment in your tank year round. If you need the tank cleaned there are service that specialize it just that thing as well as polishing the fuel. It is also a do it yourself job for anyone who is mechanical inclined and willing..........

Perhaps more than you want to know about biocides, but here...
http://sail-delmarva.blogspot.com/p/diesel-biocides.html

It is important to note whether the solids looked like snot (bugs) or tar (fuel oxidation).

Stu Jackson · Apr 21, 2010

s sauer said:
A more effective option is to remove the fuel line from the tank at the Raycor filter and use a hand pump to remove all fuel to fuel can(s).

Hand pump? Why not use the electric fuel pump?

There was a parallel discussion of just these issues on the C36 Message Board just this week. The concept was about removing water from a tank, but getting the old fuel out ideas could apply here, too.

http://www.c36ia.com/forums/showthread.php?t=699

========================================

Whoa...wait a minute. No need to call a pro.

Water in the fuel is not a difficult fix, so you can save a lot of bucks by doing this one yourself. First, the good news...you spotted the problem before you started the engine. Therefore, the water is only in the fuel tank and lines, and probably the Racor filter. The Racor has certainly stopped it at that point.

Here's the fix...

1. Go to Lowes/Home Depot and purchase about 25 feet of translucent plastic refrigerator water line. The stuff that's about 1/4 inch O.D. Get a coat hanger. Straighten the coat hanger and tape one end of the plastic hose along its length, so that you can use it as a probe into the corners of the fuel tank. Coil almost all of the refrigerator hose into a 1 to 1 1/2 ft circle and tape it so, leaving the top end free. It looks like a French horn, sort of. Put on appropriate background music if you think it helps.

2. Drain the sump on the Racor until all visible water has been drawn. Deposit into a container nearby.

3. Open the fuel tank access port, and probe into the corners of the tank, sucking on the other end of your 20 to 25 feet of refrigerator line. You can watch the fuel/water progress up into the hose, and it will visibly circle round and round. You can easily see when it gets near the top end of the hose. Needless to say, stop sucking before you get a mouthful of diesel. Blow the fuel into a container at hand.

4. Repeat 3 as needed, until all water is out of the recesses of the tank.

5. Repeat 2.

6. Replace the Racor.

7. Put everything back together - REMEMBERING to close the fuel tank access port WITH THE GASKET IN PLACE.

8. Start the engine and run it for an hour to convince yourself that what you've done is a proper fix. (It is. And probably your pro won't have done the fix as completely as you will.)

9. Last thing, use the refrig hose to draw off the water from the bottom of your container, and then dump the diesel into a friend's diesel truck or car. Properly dispose of the remaining 1/2 cup of contaminated fuel.

Not mentioned in this list is the obvious sequence of when the fuel shutoff will have to be closed, and opened, etc. Just work it through logically. Going slowly, taking your time, I'd guess about two hours total, not counting the trip to Lowes. It's not sweaty hard labor...just careful, methodical, and a little bit messy. If you're careful, the mess can be readily managed. Remember, you're dealing with flammables, so no smoke break until after you shower.

(Sorry, but was away at the boat, in Canada, for the weekend and couldn't stay up with the posts.)
__________________
Larry Brandt - Mk II Tech Editor
S/V High Flight #2109
Pacific Northwest, PDX-based
2002 C-36 mkII SR/FK M35B

I think I would modify Capt Brandt's suggestion a bit. Borrow enough 5 gal fuel containers from friends in the marina to hold the contents of your fuel tank. Put a piece of hose on your racor output barb and pump the contents of the tank into the borrowed jugs. Either have a helper turn the key off and on as the jugs get full or simply turn off the battery switch. When the pump looses prime, put the loose end of the clear coil on the pump input and finish draining the tank into a throw away container.

Change your racor. You should probably have at least one spare racor on hand before you start just in case you foul one part way through the draining.

Reattach the removed fuel lines. Refill the fuel tank from the jugs. If you are concerned there may still be water in the fuel, use a baha filter or similiar. I think I would also add a diesel additive that absorbs water just in case you missed some.

C34 #1090
Past C34IA Commodore
Chesapeake Bay

Stu Jackson · Apr 21, 2010

Sometimes there are screens on the pickup tubes. The screen should be removed.

sailingdog · Apr 21, 2010

That should work fairly well. Both polycarbonate and neoprene are fairly compatible with diesel fuel.

Bob S said:
I am planning on cleaning my tank before launching this year.

If you cut a 4-6" access hole can you use a piece of Lexan polycarbonate to make a cover? Will it stand up to diesel fuel? I was going to cut a piece of neoprene rubber as a gasket.

Comments would be helpful.

Bob S · Apr 21, 2010

Thanks Dan

Dan Johnson · Apr 21, 2010

Bob S...

Take a good look at the SeaBilt product before you proceed with the Lexan solution. If you set it up in the same manner, you might have success in keeping the fuel in the tank and not leaking out. They are made for commercial installations.

Here's a picture of mine installed in my H34's tank top. Others on these forums have turned to them after less success with alternative solutions (I don't work for them and they're a privately held company).

Richard Bryer · Apr 21, 2010

This is a job I did about 4 years ago. I did it while on the hard - makes life easier. I siphoned the fuel out of the tank into a clean new large garbage can ( I had a full tank). I used a piece of garden hose- other wise you could be at it for a long time. I then cut a hole in the Poly tank- easy to do with a utility knife. You will be amazed at how much gunk is in there ( only siphon down to the last gallon or two) I took a gallon and a half of muck that looked more like it came out of an eaves trough than a diesel tank. Wipe the tank down thoroughly with lots of paper towel or clean rags.

I sealed the hole with a piece of 1/8 lexan sealed with Peramtex - used the blue tube that says impervious to kerosene.The thinness helps the cover conform to the curvature of the tank- they all seem to develop a concaveness. I screwed it down with self tapping screws- drilled and ran the screws in first then wiped the inside again to get the shavings out.

Here is a picture

Bob S · Apr 21, 2010

Richard,

Nice job. Have you ever had a problem with a leak or smell permeating from it? Since you did it have you had to remove it? Seems like it would be tough to clean the Permatex. I like the size of the opening. I have an aluminum tank. I'd use a hole saw and fabricate something similar to the SeaBilt version but using a Lexan cover for visual access. My boat sat for 4 years on the hard before I bought her. I have no idea if she had a full tank or not. I haven't had a problem yet but do see a few black granular specs in the bottom of my Racor filter.

Dan,

The SeaBilt product is top notch and you're installation looks real clean. What holds the bolts from falling into the tank when you remove the nuts? I do like the idea of being able to see into the tank without having to remove the cover.

Bob S · Apr 21, 2010

Mike,
I didn't mean to hijack your thread. Seems like a daunting task that I'm not looking forward to but I'm afraid of what might happen if I neglect to.

RichH · Apr 21, 2010

Here are some postings from the past on the exact same subject:
http://forums.sbo.sailboatowners.com/search.php?searchid=1158444
http://forums.sbo.sailboatowners.com/showthread.php?p=563074

Your technical bottom line is that you ***have to clean the tank***. One method if you dont have access ports is to 'cut' such into the tank. A second method is to put steam or power washing hosing down into the tank's inlet nozzle (but such wont clean anything behind baffles, etc.). The reason for the 'bottom line' of a totally clean tank is that most of the tank 'debris' is most probably a fungus infection (C. Resinae - a very common organism that uses kerosene and diesel fuel for its nutrient source and can be with or without water contamination to the fuel) and if you dont get almost ***ALL*** the still viable organisms (sticking to the tank walls) out of the tank .... then it only re-infects at an exponential rate.

There are some new chemical 'tank cleaners' entering the market, such as Star brite "Fuel Tank Cleaner" .... but you have to use a LOT of it and your ARE going to possibly use a LOT of filters until the tank returns to 'respectable particle levels'.

The very best is start fresh with a hand-scrubbed CLEAN tank, keep the minimum amount of fuel in the tank, drain the fuel for long term storage, .... and to prevent further contamination, consider to apply a simple 'on-board' recirculation polishing system. An onboard recirc polisher will keep the 'seed particles' (which continually 'grow' or agglomerate into progressively larger and larger particles - for less 'particle challenge' to your Racors.

Forget about 'fuel polishing', forget about 'pumping' the fuel out - as most tank 'diptube' dont reach the bottom of the tank. Remove ALL the fuel (& burn it in you home oil burner), scrub the tank walls, and START with a CLEAN tank.

BTW - most marine diesels require only a 15µM (@ 100% removal efficiency) filtration. If you have 2µM Racors installed, they will most likely fail/clog ~7-10 times FASTER than a 10µM Racor in 'normal' marine service. Worse, a 2µM will develop a LOT of differential pressure across it ... and those particles which many are deformable will extrude right through the 2µM; since they dont 'burn' very well, then expect them to form a lot of 'coke' and eventually start to block the exhaust system

If you have visible water in the fuel ... the fuel is either been in the tank for so long that its now totally saturated with water from the atmosphere entering through the VENT (....read: VERY VERY 'old' fuel); OR, you have a leaking deck fill.

Moral: Routine tank clean outs on a periodic basis, dont keep the tank 'topped off', totally remove the fuel when long term storing the boat, buy your fuel only from 'high turnover' sources such as truckstops or marinas that cater to 'commercial watermen', etc.

If you dont have access ports and intend to install some, then remove the fuel as best you can ... and FILL THE TANK WITH WATER before you start cutting it ..... so it doesnt "go boom" while you are cutting into it.

Richard Bryer · Apr 22, 2010

No problems with leaks or smell. I talked to a surveyor first and the ABYC spec for pressurizing the tank is only something like 3-4psi. I have not removed the cover since I put it on, I do anticipate having to carefully remove the Permatex, probably with something like a razor blade paint scraper. The hole is 7"X7", cover 1 inch bigger

BTW- this is a diesel tank- I have never considered there to be a big danger from explosions due to sparks. Anyone ever see or know first hand of an explosion with diesel in like circumstances?

Dan Johnson · Apr 23, 2010

Bob S...

the SeaBilt port's bolts are mounted on two half rings so you can insert them through the access hole into the tank then feed the bolt threads through the provided ring gasket then up through the holes you've drilled using the lid as a guide.

I drilled the first hole, put a bolt through the lid and into the hole, then drilled the second hole on the opposite side and did the same thing. Then, using the lid as a template so as not to misalign the holes for the bolts to come up through cleanly, I drilled the remaining holes.

If your tank has the concaveness in the top as Richard pointed out, you will need something stout in thickness to clamp up solid to the tank top to have the concaveness taken out so you don't get any leaks.

Your other post mentions plexi or Lexan but MaineSail points out the issue if there's a fire aboard in that area. I'd go with an aluminum set-up for the strength if you DIY. You can't see into the tank without a strong light source anyway.

Ron McCoy · Apr 24, 2010

Some good ideas and some not. I'd prefer an tank port that can be accessed occasionally. Vacuum the bottom of the tank every other year, keep the tank full during the off season, refill used fuel on a regular basis and keep your filters changed. That's all that's needed. BTW: Diesel has a very high flash point - it doesn't go "boom". It's difficult to burn even when a flame is applied to it.

Cleaning out diesel tank?

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