The Fuel Tank Project (Part I)

The Fuel Tank Project - wish we didn't have to do this, but.. Alex was very determined and after much deliberation, the project is now underway. After all the hard work we put into cleaning & repairing the engine, we did not want to risk dirty diesel spoiling it. 

The fuel tank is 20 years old and has never been cleaned. What's the objective of this project? To add an inspection port, clean the inside and install a fuel polishing system, comprised of a fuel pump & 2 filters, to keep it clean thereafter.

Of course like a lot of things on board, the tank was installed in such a way that it was never intended to be accessed post install {go figure}.. So Alex had to cut an access hole in the wall of the queen sized cabin.

The initial access hole

Unfortunately, as you know, nothing is ever quite that simple, easy or straightforward on a boat. After spending several hours unsuccessfully attempting to take it out, he ended up having to remove the entire wall! 

Could not, would not come out! until..

The entire wall was removed

We carried the tank out and placed it under the boat so we could work on it with ease. Of course this did not go as smoothly as planned; even though we drained as much diesel as we could, some residual diesel still spilled out onto our luggages in the cabin as we were carrying the tank out 😖 {diesel really smells bad!}.

Fuel tank under the boat

We cleaned the outside of the tank with a scour and rust remover. The tank looks pretty good, except for the bottom which has some deep pitting (probably from standing on a wet base for a long time).

Alex then made the inspection port backing plate & cover from two (12" x 9") 3mm stainless steel plates. Drilling the holes in the stainless steel plates was a pain. We had to drill 14 holes on each plate. Oh and by "we" I mean Alex, while I helped to clamp the drill guide tool and hold down the table {hard work!}.

Each hole started off with a 1/8" drill bit (until both broke and we finished the job with a 3mm drill bit), then a 3/16" drill bit and finally a 6mm drill bit. That's 3 times per hole x 14 holes x 2 plates! Making it a total of 84 times of aligning the drill guide to the hole, clamping it down, changing the drill bits, placing it on the bench vice, and of course the actual drilling!

Update: Alex later enlarged the 6mm holes on the cover plate to 7mm to allow for thermal expansion of the cover plate.

14 holes per plate

In case you were wondering, the drill guide tool is that vertical piece with holes (made from nickel-alloyed steel that is heat treated for durability)

Cutting out the middle with an angle grinder to make the backing plate

Fortunately, we bought the 'drill guide tool' in June. It helps to keep the drill bit perpendicular to whatever you are drilling -- like a portable (poor man's) drill press for precision alignment. It works well. Having said that, we still broke a couple of drill bits but that was due to placing the clamps a little too close to the drill hole and when the drill chuck "hit" the clamp, it snapped the drill bit.  

Next, we tried our best to flush out the residual diesel in the tank with soap and water. As a safety precaution, we filled up the tank with water before Alex cut out the inspection port hole with an angle grinder. Very glad all went well -- no explosion.

Marked, drilled some holes and cut out the hole with a grinder

Alex used the backing plate to mark the holes on the tank and smoothed the edges with a file.

With the access hole, we were able to stick our arms in to scoop out the sludge and clean the inside of the tank with a scour and detergent. For the bottom of the tank, where we could not reach, we used de-greaser and a Karcher K2 pressure washer which we borrowed from our friend Tony. We loved the pressure washer! Very compact and powerful. It's definitely on our "to buy" list, whenever we can find a 240V version!

Cleaning the inside of the tank with pressure washer

The tank is now clean inside and out! 

Top left & right: The sludge from inside the tank {yuck}
Bottom left & right: Before and after using de-greaser & pressure washer

Next steps: To get the bolts welded onto the backing plate, paint the bottom of the tank (maybe?), and order the fuel filters (Racor 500FG & 10" stainless steel Shelco), pump (Walbro FRB-22) & variety of connection fittings from the US. 

Till our next update!