Diesel Fuel Polishing - Catalina 270

[PaulDaniel]

I know much has been written on this topic. It seems everyone approaches this slightly differently. My fuel tank does not have an inspection port, so it is impossible to completely clean out the tank.

Here are some strategies that I have read about or thought of:

1) Don’t polish it. Just keep a lot of extra filters available and be prepared to use them.
2) create portable standalone fuel polishing system with fuel pump, filter, and wand, so that you can polish the fuel tank whenever you feel the need.
3) create onboard fuel polishing system that you can run whenever you want at the press of a button. (This is mostly just appropriate for cruisers who have to routinely get diesel from questionable sources)
4) instead of creating a separate fuel polishing system, just pump out the diesel from the outlet of the racor filter that is already on your boat. (You could use a drill pump for this). If concerned, you could cycle it several times.
5) instead of filtering the diesel, just syphon or pump it out and dispose of it, and put in fresh diesel.
6) instead of trying to clean out a moldy rusty tank with no inspection port, just buy a new fuel tank (cost about $1k not including labor)

I just bought the boat. I haven’t had any fuel filters clog up but I haven’t had it very long. The previous owner had fuel sitting in the tank for 7 years so I assume there is growth in it. I am inclined to use method 1, 4, or 5. I bought Biobor JF and Startron to use as fuel additives. But I’m concerned that adding them will dissolve a LOT of stuff that is going to clog my filters. Perhaps instead of polishing the tank, I can just start using additives and keep a lot of filters on hand?

 

[Ralph Johnstone]

Maybe back up to a little before you first paragraph. If you don't have an inspection port, you could install one of the add on devices on the top of the tank. That wouldn't be my first choice however as diesel has a terrible history of leaking on gasketed surfaces. What I did install was a small SS disk with a 3/8" NPT plug and the usual telon tape and thin layer of Permatex #2 sealant on the plug which I've never seen leak yet:

The stuff oozing out of the underside of the SS disk is a good dose of Permatex #2.

Every couple of years I'll pull the 3/8" plug and run a small tube from my Pelor vacuum oil pump down into the bottom of the diesel tank and pull a long continuous sample. The small vacuum tube comes up through a short length of clear 1/2" vinyl tube and I check for crud in the fuel as it slowly goes through the larger dia. vinyl tube. I keep dragging the tip of the tube along the bottom of the tank checking for algae. The small Pelor tube has a thin piece of spring wire in it to guide it to where you want it to go. I have not seen a sign of algae in 27 years nor a trace of dirt in my primary filter after a change.

Maybe the lack of dirt is from clean living, or the BioborJF that goes in after every fuel fill up ? ? ?

 

[kappykaplan]

Maybe the lack of dirt is from clean living, or the BioborJF that goes in after every fuel fill up ? ? ?

My vote is for the latter, Ralph!

 

[Ralph Johnstone]

My vote is for the latter, Ralph!

Hmmmm. Guess you've seen me on Saturday nights then ?

 

[kappykaplan]

Hmmmm. Guess you've seen me on Saturday nights then ?

Maybe . . . Can't be 100% sure.

 

[Davidasailor26]

If the old fuel has been sitting for 7 years I’d consider pumping it out and starting fresh. Doing that with the amount of fuel a 27’ boat can hold probably won’t be prohibitively expensive. Having said that, it might not prevent all problems if there is growth stuck to the tank itself. Maybe replace the fuel then keep an eye on the filters for the first few hours of runtime after that. If they start clogging you know there’s a problem inside the tank and you can get it professionally cleaned. If you plan on taking a trip where engine loss would be catastrophic before you get a chance to watch the filters then maybe be more proactive.

 

[PaulDaniel]

Right on.

There was maybe a 1/4 tank of old fuel, and the he topped it off with another half tank before I bought the boat.

I don’t think there are any professional services around me that will polish the fuel. I’m on a small lake with no big marinas or boat yards.

I think a reasonably approach that is proactive without going over the top or creating extra work for myself would be:

1) add Biobor and Startron to existing fuel (maybe let it sit for a day to bust up some grime)
2) empty tank by pumping fuel from the outlet on the existing racor 10 micron filter
3) perhaps cycle the fuel like this a handful of times, while changing filters as necessary
4) when satisfied with fuel cleanliness, call it a day.
5) continue using fuel additives and keep a handful of extra fuel filters on hand

Y’all tell me if this seems like a bad idea. I like this plan because I don’t have to build any fuel polishing system. It may not completely clean all of the (assumed) gunk in the fuel tank, but it seems like it would get most of the bad stuff out and give me a good start.

 

[PaulDaniel]

Ralph,

I would love to have an inspection port in my fuel tank. This might be a dumb question, but how do you cut an inspection hole or pipe fitting without getting metal in the tank. I assume this would be unavoidable and you would have to filter the fuel and clean tank after installing an inspection port.

Thanks y’all.

 

[jssailem]

I don’t think there are any professional services around me that will polish the fuel.

You might croak at the cost they would quote. I have two 85-gallon tanks. They wanted $2500 per tank in 2016. I took a pass.

 

[Ralph Johnstone]

but how do you cut an inspection hole or pipe fitting without getting metal in the tank.

The metal cuttings are pretty hefty compared to the microscopic garbage that normally floats around in your tank. You've got two filters to deal with this IF the particles ever get lifted into the fuel through wave action so ignore them. They're big and they don't plug filters.

The rest of your ideas for n the fuel seem like a good idea but maybe take a good book with you to pass the time.

Having hypothesized all that, maybe put some time in to getting a peek into the tank to determine what IS in the tank. Every so often one gets lucky .

 

[jssailem]

What type of metal was used for the tank?
You can use a hole saw to cut the hole. You can use a vacuum to suck up the metal while cutting the hole.
Not perfect, but doable. If the metal is magnetic, a magnet can be dropped through the hole to pull up any shavings. The fuel filter will capture any big pieces that find their way into the fuel lines.

Your approach is reasonable. You might go out for a sail to stir the tank while the additives do their thing.