• From: Fredericton
  • Registered: 2010-09-06
  • Posts: 11

Topic: How do you clean the diesel-fuel tank? Help!

Hi
The co 26 I just purchased has been sitting on hard for 4 years. The fuel (diesel) tank was about 1/8 full. I decided to siphon out the fuel to replace with fresh diesel. As I siphon the fuel through transparent tubing found out that there was some dark crap sitting at the bottom of the tank and now running down the tubing along with the fuel. What is it? Algae? What else could it develop there? (It looks more like a gelatinous soft thingy.)
Now I would like to clean the tank and if the thing gets worse may be even clean/replace the hoses.
So, now, what is the best/common way to clean all that stuff from that metal tank? Can I clean it with the tank in place? Do I have to take it out? And if I do how do I proceed? How do I clean it with?
Your help would be most appreciated. Thanks.

  • Registered: 2005-03-10
  • Posts: 143

Re: How do you clean the diesel-fuel tank? Help!

The only thing I am ware of is, is that your best bet would be to take it out, and let the sludge drip out and then try to slosh around some diesel fuel to break it up - not very scientific  - I am not aware of any products out there but there might be.  I think the sludge is actual residue from the tank over time and from the fuel as it sits for a long period of time

Ivan Ross "Morava" #266
  • cPaul
  • Veteran Member
  • Offline
  • From: Montreal, QC Canada
  • Registered: 2008-08-18
  • Posts: 72

Re: How do you clean the diesel-fuel tank? Help!

Hi Picard,
I had the same issue with my Contessa -- boat and 30 year old Farymann 7.5 hp had been poorly stored, and left to stand in a farm field for 5 years.   I siphoned crankcase, gearbox, 1/4 tank of old diesel -- replaced lube and fuel... engine started up first time when I hooked up new battery and hit the switch!   Second season, I removed the fuel tank, cleaned with diesel (you can also have this professionally done), and changed the Rancor fuel filter (messy job).  Next season will be my 3rd with the boat -- will change all fuel lines, due to their age.  The mess on your lines is probably dirt/oil, and softened tubing material... mine are the same way.  If I were you, I would remove the tank and have it cleaned professionally.  Next season, I'll be replacing my big old steel tank with a Vetus 5 gallon tank.  As it is, I barely go through a 1/4 tank per season.  Frankly, I could use the stowage space...!

"Lolly Jo" #230
C. Paul Carter
Montreal, QC

cPaul's Website

4 Reply by Viragodeb (edited by Viragodeb 2010-10-06 12:30:17)

  • Registered: 2010-09-30
  • Posts: 18

Re: How do you clean the diesel-fuel tank? Help!

What about using suction?  I use a vaccum oil extractor to change my engine oil - a plastic cannister that in which you create a vaccum and it sucks out the warm engine oil.  I'd certainly use that to suck up sludge  - maybe a repeated cycle of add a bit of fuel, stir, suck.   You could use a shop-vac.  We use a slimy old one at work for sucking up oily bilge water, small diesel spills etc. (diesel  **NOT GAS**).  Removing the tank would be the surest way, but if your boat's like my boat you may not get the tank out through the cockpit hatch - the tank may have been installed before the deck was put on so you may need a plan B.  Suggest putting a fuel shut-off valve on the top of the tank where the fuel line attatches if there isn't one there already (wasn't on mine) as it makes working on the fuel system tidier and the whole system safer.  A petcock can be purchased for about twenty bucks and it's a snap to install.

  • Registered: 2010-04-03
  • Posts: 22

Re: How do you clean the diesel-fuel tank? Help!

Hi that sludge is the awful algea that gets in the bottom of the tank with all the corn oil they add to diesel it attracts moisture so a steam clean of the tank change the hoses and clean fuel and a good dose of stabilizer will do the job  the fuel mixed with moisture turns into that sludge......  just replaced the head gasket on my Faryman   gasket cost $50 and a couple of hours work cleaned all the carbon off the head and piston   running like a top now !  Phil

  • cPaul
  • Veteran Member
  • Offline
  • From: Montreal, QC Canada
  • Registered: 2008-08-18
  • Posts: 72

Re: How do you clean the diesel-fuel tank? Help!

Phil -- What maximum knots do you get out of your Farymann? 

Mine seems to run well, but can only manage 2.5 kts at best.   Desperate situation against 15kt headwinds with no sails up!!

"Lolly Jo" #230
C. Paul Carter
Montreal, QC

cPaul's Website

  • Adrian
  • Adrian
  • Administrator
  • Offline
  • From: Toronto, Ontario, Canada
  • Registered: 2005-04-18
  • Posts: 542

Re: How do you clean the diesel-fuel tank? Help!

Paul, that sounds like a prop size mismatch, on first blush. Might be worth talking to someone about the best prop for your engine.

Adrian's Website

  • From: Mississauga, Ont. CA
  • Registered: 2008-03-16
  • Posts: 20

Re: How do you clean the diesel-fuel tank? Help!

Just my 2 cents worth, but my 8 hp Bukh gives me roughly 4 knots when the throttle is about 1/2 to 3/4.
Does sound like your prop/ engine needs some adjustment.

cheers, kevin

  • Registered: 2010-04-03
  • Posts: 22

Re: How do you clean the diesel-fuel tank? Help!

Hi Paul  just today installed the new voltage regulator  and fired up for a run out  blowing hard 35klms right on the nose  threequarters throttle into the wind and a pretty good  chop  so lots of spray 4.5-5knots on the log did`nt use the gps  --- could well be your prop or even bad compression  how easy does she fire up   might be worth while doing a compression test  I do have a copy of both the handbook and workshop manual if you need it  let me know  Phil

  • Registered: 2009-07-25
  • Posts: 112

Re: How do you clean the diesel-fuel tank? Help!

  • Registered: 2010-04-03
  • Posts: 22

Re: How do you clean the diesel-fuel tank? Help!

Hi John its a phocopy a bit dark but happy to share it let me know  Phil

12 Reply by stefan_d (edited by stefan_d 2010-10-08 08:55:52)

  • From: Ottawa, On
  • Registered: 2005-03-10
  • Posts: 353

Re: How do you clean the diesel-fuel tank? Help!

Yanmar 1GM10, 2.62 reduction ratio, 12X10 pitch 2 bladed campbell sailor and I can cruise along in flat water at 5 kts.  (~2750-3000 revs)  Trying to punch thru any kind of decent headwind is really not worthwhile, and I usually fly a working jib and tick tack, the ride is a lot more comfortable.  In tight spots, one can motorsail too.......

stefan_d's Website

  • cPaul
  • Veteran Member
  • Offline
  • From: Montreal, QC Canada
  • Registered: 2008-08-18
  • Posts: 72

Re: How do you clean the diesel-fuel tank? Help!

4.5kts would be luxury!   Engine fires up fine... will be time to call a diesel mechanic in for a look-see next Spring. 

I smell "expensive".

"Lolly Jo" #230
C. Paul Carter
Montreal, QC

cPaul's Website

  • From: Ottawa, On
  • Registered: 2005-03-10
  • Posts: 353

Re: How do you clean the diesel-fuel tank? Help!

what are you running for prop / reduction ratio?

stefan_d's Website

  • Registered: 2009-07-25
  • Posts: 112

Re: How do you clean the diesel-fuel tank? Help!

  • Registered: 2010-04-03
  • Posts: 22

Re: How do you clean the diesel-fuel tank? Help!

John did you get my email ?  where are you located ?  Phil

  • Registered: 2009-07-25
  • Posts: 112

Re: How do you clean the diesel-fuel tank? Help!

  • From: Victoria B.C. Canada
  • Registered: 2010-09-14
  • Posts: 5

Re: How do you clean the diesel-fuel tank? Help!

You really have to remove the tank to scrub the sludge off the insides unless there is a large inspection hatch on the tank top. Emptying it will not eliminate future problems.