Diesel Polishing

[Simi 60]

Originally Posted by slug

Nothing went wrong

To avoid clogged filters clean your tanks

Read my post again.

We have NEVER cleaned our tanks
We have NEVER found any hint of contaminates in the crud sump when drained
We have NEVER used biocide
We have NEVER had a clogged filter or any hint of clogging

[Simi 60]

Originally Posted by Poche

I added biocide to 15 gal. in my diesel tank in the new to me sailboat.
The lines and filter immediately clogged. The engine stopped like you turned off a key.

So are you saying if we tip in enough biocide to treat several thousand litres of diesel we will instantly get clogged filters?

[Bundyon]

I am about to cut a 12 inch square to my built in metal tank of 1000litres (270 US gallons)
This fuel tank has never been cleaned since the boat was built (1991) I purchased the boat last year and carried out a major refit prior to sailing the 600odd nm back to my home port. During the refit I had installed a Racor 500 as my primary filter and a single CAV 796 was already fitted to the engine, this became the secondary filter. The tank had approximately 900 litres of diesel in it at the time of purchase, I topped it up prior to departure and also poured some top quality biocide in for good measure. New filters were fitted (10micron in the Racor).
Due to sail & rigging problems that we wanted to sort out back in my home port, it was decided to run on the engine back to our home base. Engine is a 4-236 Perkins 80h.p.
At the end of every day, whilst on anchor, I would drain the water from both filters with the electric fuel pump running to flush the filter bowls. No blockages at this point. Coming out of the Southport Bar at 0730 straight into 5 metre seas pounding us on our Port beam as we ran down the coast making for an uncomfortable run, heading for Iluka, we arrived off Iluka/Yamba Bar at midnight and decided to racetrack 5nm off the coast until slack on the high tide at 0700 before tackling the notorious bar. The Perkins was blowing a fair bit of black smoke which indicated to me that the fuel filters were blocking up, not surprising, considering the almost 24hour severe shake up the fuel tank had just had.
We made it into Iluka Lagoon and anchored up. With only another day run to get home, I decided to replace the filters. The fact that the Perkins could still run on the state of these blocked filters and the state of the water diluted diesel is testament to old school engineering. I have no doubt if this was a modern electronic diesel with Common Rail , we would have been doing a filter change every day and would definitely have had an engine failure at sea. I have enclosed several photo's of the Racor and the CAV upon removal at Iluka. Once I have cut the tank open, I will post up more pic's of what I find!
I was quoted between 3-5K to polish the fuel in my tank. Being on a Military pension & a mechanic, I am happy to do it myself. Expensive multi banks of filters aren't needed imho, on sailing boats. Start with a clean fuel tank, maybe a sediment bowl then a quality Primary filter followed by a quality secondary filter & regular maintenance/ checks. A visual Check on the sediment bowl will tell you the state of your fuel. 250ml of quality biocide per 1000litres will keep the bugs in check.

[Poche]

Originally Posted by Simi 60

So are you saying if we tip in enough biocide to treat several thousand litres of diesel we will instantly get clogged filters?

Nope. I put in maybe half a thimble full.

[Lepke]

As a former yard worker and later yard owner, I've seen a lot of dirty fuel tanks. Our main clientele were commercial boats, tugs and small ships. Some sat months and others years between jobs. And some had tanks only used when they needed to carry maximum fuel. The ones with poor engineers usually had no lay-up procedure. I could fix 99% of them with a 3x dose of a good fuel conditioner and some circulation. Most bigger boats already have a plumbing system that allows pumping to and from the same tank and a pass thru filters. It was a lot cheaper for our clients to treat the tank than to pay someone to go inside and muck it out. We used a finer filter, about 1-2 micron. And it was rare for one to plug.


All the dead organisms and sludge doesn't immediately become loose and mix with the fuel. It takes weeks. And a black filter media doesn't mean it's plugged, watch the vacuum gauge. Carry spare filters.


If you use a lot of fuel on a consistent basis, then you're fine. The additives coming from the refiner last several months. But new fuel is only good for about a year without treatment. Put some in a jar out of the sun, and watch it change. A good conditioner kills organism growth, help a good primary filter (like a Racor turbine) remove water, adds a lubricant, improves combustion and reduces soot. I use a conditioner every fueling and in about 60 years never had a bad fuel problem in my own boats and boats I ran for other people. The only fuel problem I had in all that time was running out of fuel under a lift bridge when I was a kid. I use a 2 micron in my Racors.

[Simi 60]

Originally Posted by Lepke

. But new fuel is only good for about a year without treatment. Put some in a jar out of the sun, and watch it change.

Does the inside of a diesel tank ever see the sun?

[RaymondR]

And many diesels will run on home made diesel made out of waste cooking oil and fats which do not have any additives.

[slug]

Originally Posted by Simi 60

Does the inside of a diesel tank ever see the sun?

No sun , but diesel fuel in the tank does get hot

Heat seems to promote growth inside the tank

[slug]

Originally Posted by Simi 60

Read my post again.

We have NEVER cleaned our tanks
We have NEVER found any hint of contaminates in the crud sump when drained
We have NEVER used biocide
We have NEVER had a clogged filter or any hint of clogging

Gee, rather than wasting words simply open your tank and show me a picture

[s/v Jedi]

If your tank is 10+ years old and you don’t have a sump with drain or a polishing system that draws from the tank bottom then I agree with Slug that crud will accumulate on the tank bottom. Using enzymes may keep tank walls clean (not when starting with a foul tank) the sludge is another matter that needs to be polished out for one part and mixed through the fuel again for the part that passes 30 micron filters. It requires circulation of the fuel incl. from the tank bottom where pickup tubes don’t reach.

[a64pilot]

If you ever, ever get even a drop of water in your filters, thats a your problem that needs to be fixed, the water intrusion. If you regularly have to drain water from your filters and don’t use a biocide regularly, you will have problems, maybe not today, but it’s coming. In a case like that biocide is a band aid, it will stop bio growth before it occurs, but you need to get rid of the water, not band aid it with biocide.
Only time I have ever gotten water in a filter, we got a lot in my Brothers boat, we finally traced it to the O-ring in the fuel cap, thought it was the vent, but it was the cap.
Yes fuel will have dissolved water in it, that’s unavoidable, but it shouldn’t ever really drop out of suspension. If you have water in your fuel you need to fix that, a reputable supplier will filter the fuel as it’s dispensed and their filters have water blocking media too.
If your buying fuel from someone that doesn’t, then don’t or if you have to have the fuel, put it in jugs so you can inspect it before it goes into the tank.
Try not to buy fuel from Jim Bobs fish camp, but buy it from a place that pumps a lot of fuel.
I have no experience with a Baja filter myself, but they reportedly work.

[noelex 77]

Originally Posted by slug

To clean the tank open it up , pump out fuel , scrub with a long handle scrub brush , pump out bulk sludge , high pressure diesel fuel wash the tank , pump out , high pressure diesel wash again , pump out

If you are finding the tank needs cleaning out and scrubbing every two years that is a pretty strong argument for fitting a polishing system.

[a64pilot]

Originally Posted by noelex 77

If you are finding the tank needs cleaning out and scrubbing every two years that is a pretty strong argument for fitting a polishing system.

I’d say it’s a pretty strong argument for buying clean fuel, my backhoe and tractors were all over 30 years old and the tanks had never been cleaned, know any one who polishes a farm tractor, construction equipment, trucks?They also would sit for long periods between use sometimes even more than a year.
So what is the source of this “Junk” maybe that need investigation, or just keep cleaning it out?
My boat is 33 years old and has never had its tank cleaned, I know as there is no way to get into the tank, and I don’t clog filters and don’t ever get any water in them. It’s been two years I think since my filters were changed, I’ll likely change them this year cause two years is enough don’t you think?
I guess I could flip to the other filter and go for four years?

[Bill O]

Originally Posted by a64pilot

If your buying fuel from someone that doesn’t, then don’t or if you have to have the fuel, put it in jugs so you can inspect it before it goes into the tank.
Try not to buy fuel from Jim Bobs fish camp, but buy it from a place that pumps a lot of fuel.
I have no experience with a Baja filter myself, but they reportedly work.

The deck fill filters do work. Here's an old PS review of them.
They don't make the Baja filters any more (can find used), but we use the WM one (not sure if that's available any more either) and works great. There brands out there (Mr. Funnel) that can do up to 12 gal/min.

You should get into the habit of looking at the fuel in a jar before you purchase the fuel. You'll be surprised sometimes at the junk in some of them from more reputable marinas. Have had several friends fill up on ICW marinas only to have their motors shut down due to hefty amounts of water taken on w/the new fuel (pumped gallons of water out of the tanks).

[a64pilot]

Usually, but not always if you go to a fuel dock that the Sportfisherman use, they are a high volume seller and most often seem to maintain their equipment, selling fuel is a large part of their business.
Try not to buy fuel when they are having fuel delivered, reason is the delivery can stir up the tanks and you may get some dirt that way.
Joes fishing shack may sell fuel, but usually not very much as he sells it to get people into his bait store or whatever and due to his low volume his fuel may be old and possibly contaminated.
Then I’ll go out of my way to buy a Valvtec fuel when available, cause I’m pretty sure they are a chain sort of and the tanks / dispensing equipment if not installed by them has to meet their standards, but I am not certain there. I try to avoid unbranded fuel when possible, it may be great, and it may not. I ask to see the final filter if it’s not mounted to the side of the dispensing station too. Almost all have water bloc or water absorbing media meaning dump water into filter and it clogs and won’t pass it on.
Funny thing but all the fuel I have bought in the Bahamas has been clean and water free, at least up to US standards, I hear horror stories but haven’t experienced it.