Diesel Tank Cleaning

[MarkRyan1981]

Has anyone gained access to their tank to give it a good scrub? I'm contemplating doing mine...

[prjacobs]

Hi Mark,
During #1085's reincarnation, after the boat had sat for 7 years, I pulled the tank out and took it to a radiator repair shop where they boiled it out for several days in a hot tank full of lovely chemicals. Even then there were still black globs of goo stuck to the bottom that only came loose with persuasion from a pressure washer. It's squeaky clean now, and I've lowered the fuel intake pipe almost to the very bottom to keep it that way.
I followed the suggestion from a forum post that in part says:

I have read that the fuel micro-organisms need water in order to live. If this is true, then if you keep water out of your fuel tanks, you will not have a micro-organism problem. The key to keeping water out of your fuel tanks is to draw the fuel from the very bottom of the tank. I have wells about the size of a cup in the bottom of my tanks and my suction pipes go the bottom of the wells. By doing this I automatically remove any and all water every time I withdraw fuel from the tank.

Putting the ends of the suction tubes an inch or two above the bottom is a technique left over from the days of professional engineers and day tanks on yachts where the engineer would drain the day tank from a valve on its very bottom to be sure there was no water in it every time he filled it up. Unless you have such a drain valve on your fuel tank, or use the well or similar technique as I do, you *will* accumulate water and associated micro-organism glop in your tanks.

A fuel preservative would be a good idea for fuel stored for months at a time, but that is only to protect already clean fuel. You really must keep the water from accumulating in the bottom of your tank.

Because of it's shape the Ballad tank has a built-in low spot at the inboard forward corner, right below the fuel pick-up tube.

As a side note, I eliminated a very persistent fuel pump problem on the Yanmar by removing the mechanical lift pump completely and installing a Facet 40288 between the tank and the engine mounted filter ... it's now running like a charm
I bought 2 pumps to have one as a spare.

[MarkRyan1981]

Thanks Peter,

I'll open it up - I suspect it'll be pretty nasty inside - How easy was it to remove the tank? I had assumed it was bonded to the hull and could NOT be removed?

Thanks!

Mark

[prjacobs]

Mine just slid out. That's not to say it wasn't bonded in before, but there was no evidence of any adhesive. I glued a thin layer of closed cell foam sheeting to the bottom and forward end of the tank to give it a bit of padding. Other than that it is only held in with battens around the forward and inboard edges. I think if I were going offshore I'd glass in a narrow flange along the top edge, along the hull ... just to be sure in case of a knock-down.