Results 1 to 23 of 23

Thread: Diesel fuel sludge questions

  1. #1
    Join Date
    Jun 2016
    Location
    Adelaide, Aust.
    Posts
    88

    Default Diesel fuel sludge questions

    First off I admit I've never inspected or cleaned out a diesel fuel tank, perhaps because my usage has only ever been light (marina access for daysailing mainly).

    But I've recently been sat down and told about the hazards that lay in wait for me unless I open the inspection hatch and clear away the sludge that will sooner or later cause those said hazards to kick in and ruin my day.

    But...there is no inspection hatch on my tank and asking around it seems that most fellow boaties' tanks don't have them either...or at least have not yet been discovered. And it follows that most confess to having never tackled the dreaded sludge hazard either. Yet none have as yet washed up on some remote rocky outcrop.

    So what's the truth here: is it something to lie awake at night fretting over; should I lift finger pronto and just do the job; or will my filters continue to do the job I thought they were designed to do?

  2. #2
    Join Date
    Apr 2005
    Location
    Hills of Vermont, USA
    Posts
    19,017

    Default Re: Diesel fuel sludge questions

    Only an anecdotal bit:

    On a very bumpy trip home I had to use the motor a lot (very long story). In 5 hours I went through 3 Racor filters, so I figured it was time to deal with it. I pulled the aluminum tanks & cut holes for inspection. The tanks were about 10 years old with quite a bit of runtime - as the former owner seemed to have motored a great deal. He also bought the cheapest diesel he could & (probably the worst part) the boat sat for 2 years on the hard before I bought her.

    I cleaned out about 1" of gunk on the bottom.

    I've heard of people having luck steam cleaning, but I wanted a way to see/reach in that I could do on my own if needed. I machined a ring for the inside & a plate for the outside. Attached the inside ring with 3 screws through the tank & then drilled & tapped the tank & ring for a bunch of screw for the covers. Got oil resistant gasket material & cut gaskets to fit. While it won't be fun getting in from the top of the tank (about 18" clearance) - at least I can now do it.
    "If it ain't broke, you're not trying." - Red Green

  3. #3
    Join Date
    Mar 2007
    Location
    East Quogue,NY
    Posts
    12,408

    Default Re: Diesel fuel sludge questions

    I second what Garret relates. My experience with desiel sludge in a tank is that the problem crops up when it's rough and you shake that crap loose.

    I'll suggest this: your tank no doubt has a sending unit installed; the thing that sends a signal to a fuel gauge? If so, drain the tank, and remove the sender.These generally have five screws set through a 1-3/4" inch diameter flange/ plate

    Then have a look around with a dentist's ( mechanic's) mirror. In fact, there are even small cameras ( ' endocscopes") one can buy that you can drop in and that run off of your smartphone. These cost like 30 bucks US dollars.

    Once you've had a peek, perhaps you'll be more confident in the next steps...whatever road you take.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  4. #4
    Join Date
    Apr 2005
    Location
    Hills of Vermont, USA
    Posts
    19,017

    Default Re: Diesel fuel sludge questions

    Great suggestion on using the sender hole to take a look!
    "If it ain't broke, you're not trying." - Red Green

  5. #5
    Join Date
    Jun 2016
    Location
    Adelaide, Aust.
    Posts
    88

    Default Re: Diesel fuel sludge questions

    Thanks for the anecdote...very salutary. And for the sender tip also. It is an aluminium tank, only small at 45 litres, and cutting in a hatch wouldn't be too much trouble. But since diesel isn't unkind to nylon (or so I've been told), would an easier way be to fit one of those $20 nylon screw-cap inspection hatches used in dinghies? If they're air-tight they oughta be fluid tight...or is that just being cheap?

  6. #6
    Join Date
    Apr 2015
    Location
    St. Helens, Oregon
    Posts
    446

    Default Re: Diesel fuel sludge questions

    I'd be reluctant to use a dinghy inspection hatch in because they're really not rated for fuel usage. That's putting a of of trust into the quality control of something that's really only designed to keep water out. They O-Rings could be made of nearly anything and you could pretty easily end up with a very expensive and messy leak. Remember...they're really not all that good at keeping water out of dinghies....how 'bout water intrusion into your fuel?

  7. #7
    Join Date
    Oct 2006
    Location
    Livin' in Oz
    Posts
    51,443

    Default Re: Diesel fuel sludge questions

    I struck a problem with it on Grantala during the Sydney Olympics. Imagine the worst marine traffic possible in the channel in Sydney Harbour... and one engine died.

    In dealing with it, I replaced the tanks... which at that stage were over 60 years old. There was over a gallon of sludge in the bottom of each 100+ gallon tank. I cut the built-in tanks out and replaced them. The sludge was like a fine brown mud.
    "Travel is fatal to prejudice, bigotry and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome and charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime" Mark Twain... so... Carpe the living sh!t out of the Diem

    I'd rather look back at my life and say "I can't believe I did that" instead of being there saying "I wish I'd done that"

  8. #8
    Join Date
    Jun 2003
    Location
    Central Coast, Ca
    Posts
    16,050

    Default Re: Diesel fuel sludge questions

    45 liters is like 10-12 gallons...
    Take the tank out drain it, clean it with some solvent shake ot up and drain it again. I wouldn't think you need to cut any holes in it.

  9. #9
    Join Date
    Jun 2016
    Location
    Adelaide, Aust.
    Posts
    88

    Default Re: Diesel fuel sludge questions

    Thanks to all. I'm probably keenest on the 'take it out and shake it' idea - (which, conveniently, would be the easiest) - and reckon should dislodge the gunk since it is the shaking at sea that is said to cause the problem.

    But a solvent for diesel sludgy tarry deposits...what might at be? I guess I could google but since you fellas are on a roll...:-)
    Last edited by Asap; 03-14-2017 at 01:53 AM.

  10. #10
    Join Date
    Oct 2006
    Location
    Livin' in Oz
    Posts
    51,443

    Default Re: Diesel fuel sludge questions

    Use the universal solvent. You are not dealing with tar, you are dealing with the bodies of dead beasties that lived in the boundaries of the fuel and water in the tank. It's mud.
    "Travel is fatal to prejudice, bigotry and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome and charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime" Mark Twain... so... Carpe the living sh!t out of the Diem

    I'd rather look back at my life and say "I can't believe I did that" instead of being there saying "I wish I'd done that"

  11. #11
    Join Date
    Jun 2003
    Location
    Central Coast, Ca
    Posts
    16,050

    Default Re: Diesel fuel sludge questions

    You may be able to sieze a rag to a dowel and "scrub" it a bit through the fill port. Look in there with a little flashlight, you might be pleasantly surprised. A few cups of mineral sprits/paint thinner as a flush after the scrub should do it. New fuel with a bit of biocide added and you should be good for years.

  12. #12
    Join Date
    Sep 2004
    Location
    Munich, Germany
    Posts
    136

    Default Re: Diesel fuel sludge questions

    I had my lesson last year. I left the dock when the engine died 100m from shore. Could't get it running again, so I driftted back and started looking for the cause. Turned out, that the fuel lines where clogged. Turned our also, that I didn't have nor a tank inspection hatch nor a fuel pre filter before the pre injection pump filter. What resulted from this was a nearly 2 day cleaning action that included the disassembly of the fuel pump as well as changing over the fuel lines, cutting a hole into the wood/epoxy fuel tank and lots of cleaning of a deep, dark tank with long sticks with rags attached to the ends and many liters of solvents.

    My lesson is:
    1. Use sluge preventigin additive regularily
    2. Have a fuel prefilter and check regularily from brown stuff and pieces
    3. Have an inspection opening in the tank, than can be used when the time comes.
    Thomas
    -----------------------------------
    panta rei

  13. #13
    Join Date
    Jun 2016
    Location
    Adelaide, Aust.
    Posts
    88

    Default Re: Diesel fuel sludge questions

    Thanks to all for your advice. Since it's a small tank I'll choose to remove it, add solvent and shake it clean. Bigger or more inaccessible tanks I can understand would need a good sized access port but I'm expecting I'll be able to get away without one. Cheers

  14. #14
    Join Date
    Oct 2006
    Location
    Livin' in Oz
    Posts
    51,443

    Default Re: Diesel fuel sludge questions

    Just stick a Karcher nozzle in it.
    "Travel is fatal to prejudice, bigotry and narrow-mindedness, and many of our people need it sorely on these accounts. Broad, wholesome and charitable views of men and things cannot be acquired by vegetating in one little corner of the earth all one's lifetime" Mark Twain... so... Carpe the living sh!t out of the Diem

    I'd rather look back at my life and say "I can't believe I did that" instead of being there saying "I wish I'd done that"

  15. #15
    Join Date
    Feb 2011
    Location
    U.K
    Posts
    567

    Default Re: Diesel fuel sludge questions

    Being as you don't even know if you have a problem yet, i would suggest polishing your fuel, either get someone to do it for you or make up a pump and filter rig and do it yourself.
    i would also have twin pre-filters, with a change over valve. i have never understood the mentality of a single pre-filter on a single engine boat. if one filter clogs up simply flip the valve and change the it at your leisure.
    Quote Originally Posted by Asap View Post
    First off I admit I've never inspected or cleaned out a diesel fuel tank, perhaps because my usage has only ever been light (marina access for daysailing mainly).

    But I've recently been sat down and told about the hazards that lay in wait for me unless I open the inspection hatch and clear away the sludge that will sooner or later cause those said hazards to kick in and ruin my day.

    But...there is no inspection hatch on my tank and asking around it seems that most fellow boaties' tanks don't have them either...or at least have not yet been discovered. And it follows that most confess to having never tackled the dreaded sludge hazard either. Yet none have as yet washed up on some remote rocky outcrop.

    So what's the truth here: is it something to lie awake at night fretting over; should I lift finger pronto and just do the job; or will my filters continue to do the job I thought they were designed to do?

  16. #16
    Join Date
    Nov 2006
    Posts
    338

    Default Re: Diesel fuel sludge questions

    If you can remove the sender, take a small engine oil pump and run a hose down into the deepest part. My huge tank has no easy access and I got curious after 15 seasons of no filter problems beyond normal changing. Plenty of violent shaking along the way.

    The samples I pulled from the deepest corners, showed clean fuel with a tiny bit of sediment. I used plastic bottles for easy viewing. I only use a Cetane booster type additive. Tanks are left over winter, full or half full. Beats me why some have problems with fuel tanks, and some don't.

  17. #17
    Join Date
    Dec 2015
    Location
    Dorset, UK
    Posts
    470

    Default Re: Diesel fuel sludge questions

    Clean fuel and maintaining a fully charged starter battery should be your obsession with a diesel engine.

    The fuel tank is likely to have sludge produced by micro organisms and potentially water from condensation forming on the walls of a half empty tank, as it will have a vent somewhere.

    If I buy a big boat, I always replace the starter battery and clean out the tank, then refit with new hoses and stainless hose clips, preferably two at 180 degrees to each other. Check the seal on the filler cap isn't letting water past. Check the welds on a stainless tank for any sign of corrosion. Check any plastic fuel lines aren't abraiding due to vibration. Check copper fuel lines are secure.

    At the same time replace the filters on the prefilter and the engine. The diesel bug will be sent back into the tank, as there is a return pipe taking unused diesel back to the tank.

    I'd only fill up from sources that use alot of fuel, or even from a jerry can from a car forecourt if I didn't use much diesel so it was clean.

    Ideally you have a main tank and a seperate day tank that is transparent and you can fill and inspect the fuel visually before the filters. Ideally you have two Racor water fuel filters in parrallel so that when one full of water or material you can switch to the other. And keep the tanks full, well secured, baffled, with low sumps, close to the center of the boat, and add diesel additive to reduce sludge build up.

    Replace the starter battery every 3-4 years, and have a solar trickle charger charging it between uses. Fully charge it with an automotive intelligent charger when you can off the boat. Don't run the battery anywhere near flat ever.

  18. #18
    Join Date
    Dec 2016
    Location
    Berlin, Germany
    Posts
    97

    Default Re: Diesel fuel sludge questions

    Remove it and pressure wash it inside. Use engine washing detergent to get it really clean. That will work better than any solvent. Rinse with gasoline to get the water out. Then fill from 20L jerrycans from your favorite gas station to always ensure clean fresh diesel. You fill the tank at the end of the day after sailing so that you always leave the boat with a full tank. That way water can not condensate inside the tank (not much that is). If you leave the boat sitting for longer or use very litlle diesel per sailing day, use biocide.

    After a while you develop a rutine. On the way to the boat stop and fill the jerrycan. Take it to the boat and leave it in the dock box. Come back from sailing, fill tank to the brim, take the jerrycan to the car. Any leftover diesel goes into the car tank. If you don't have a diesel car or friends that have one approximate the diesel needed for a typical daysail and use a smaller jerrycan (5L).
    Good luck amd keep us posted.

  19. #19
    Join Date
    Nov 2009
    Location
    Searsport, Maine
    Posts
    116

    Default Re: Diesel fuel sludge questions

    We used to have a good bit of gunk in our tank that would clog the filters after being in a lively seaway. We stopped at a yard where they could run the fuel through a couple of large filters for a few hours. We hooked up their intake to an outlet on our tank bottom for just that purpose (the engine supply line is a bit higher,) and had the inlet on a wand that could be used to spray around anywhere a baffle wasn't blocking. Got rid of our troubles. Since then, I always add the recommended amount of BioBor JF when refilling the tank at the end of the season to cut down on condensation. We also try and use a full tank each year which generally involves more motoring then we might like, but the engine needs to get its workout too. Haven't had any problems since and have been through quite a few lively seaways.

  20. #20
    Join Date
    Apr 1999
    Location
    West Boothbay Harbor, Maine
    Posts
    22,533

    Default Re: Diesel fuel sludge questions

    We have fuel tank filtering/polishing businesses that make the rounds of boatyards and civil aviation airports pretty regularly with mobile equipment. I'd be surprised if there aren't any such businesses in AU. They can filter and polish the fuel through the sender fitting.

    You can also test for water and perhaps sludge in the tanks with a paste: https://www.youtube.com/watch?v=WsdIrpyMUcA

    If you need to install an inspection hole (or new tanks) these are new to the market and can be combined with sending units, vents and fill tubes: http://www.vetus.com/news/inspection-port-ilt.html
    "It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so."

    -Mark Twain

  21. #21
    Join Date
    Apr 2000
    Location
    Barrie, Ontario, Canada
    Posts
    3,583

    Default Re: Diesel fuel sludge questions

    I don't do this often enough and got caught by it last year. Had to scrub our Northern cruise.

    http://forum.woodenboat.com/showthre...ed-ketch/page8

  22. #22
    Join Date
    Nov 2010
    Location
    Wellington, NZ
    Posts
    419

    Default Re: Diesel fuel sludge questions

    My engine stopped in the middle of "The Rip" off the south coast of Wellington last month.
    I continued travelling out of the rip with sails and the 5 knots of current going in the right direction.
    I have a 20 micron plastic prefilter fitted to the tank outlet hose.
    This was changed in 5 minutes, and the electric lift pump cleared the fuel lines of air after being left running for a minute before I restarted the engine no problem.
    As we continued home, I cracked each injector supply line just to check.
    I'm sure glad I carry 2-3 of these $5 filters.
    I need to get some treatment snake oil for the tank, some of which profess to clearing the sludge as well.

  23. #23
    Join Date
    Sep 2002
    Location
    Penngrove, CA
    Posts
    1,151

    Default Re: Diesel fuel sludge questions

    I cut a hole and built an inspection hatch into my tank.

    One lesson learned.. it must be EASY to access this hatch, or you'll never use it.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •