Fuel Tank Build-Up

[sselinger]

Thought I would pass along the following.

My boat Aquila will be 15 years old next spring. Having just pulled it for the winter, I decided to pull the fuel tank and have it cleaned. As far as I know, the boat has alway had a biocide, Bio Bore ??, used when fuel has been added. Much to my surprise there is almost no "sludge" in the tank. Only a very small amount left in the fuel on the bottom, but in solution so I think the filters would handle it easily without plugging up.

It appears that if you get good fuel and use a biocide you have little chance of a major build up of contamination in the tank.

[Randy Stolze]

Steve,

     Do you have any insights or recomendations for someone about to tackle this same job? Who cleaned your tank and how was it cleaned?

     Did you replace the fuel gauage sending unit?

 Peace,

 Randy

[Ray & Sandy Erps]

I plan on tackling this project in the next week or two.  I figured I would pull the sending unit out, thereby giving me access to the inside of the tank.  Loosen any mounting screws and then tip the tank as much as I can while still in place but so the low side is at the sending unit end.  Then stick a suction hose in and suck any loose crap into a bucket.  Depending how much gunk I get (or how much I leave in there) will determine whether I pull the whole tank out or not.  So far I've kept a close eye on my racor filter and I'm not getting much stuff in the bowl, even after bouncy days, which is reassuring in my opinion.

[Stu Jackson]

Just remember that there are (or should be) baffles in the tank, so you'd just be seeing one end.

[sselinger]

It's really simple to pull the tank. I just pumped it dry using the fuel pump, removed the port wall in the rear berth unscrewed the six mounting bolts, and removed the hoses (the hardest part after being clamped for 15 years).

I haven't had it cleaned yet, but I plan to use a local tank steam cleaning firm. I don't plan to replace the sending unit since it has always worked fine.

[Ron Hill]

Steve : Been there done that!!  
I wrote an article in the Mainsheet C34 tech Notes on removing and cleaning your C34 fuel tank and Yes, there's a single baffle.  
Read the article - I don't think that steam cleaning will get the job done for the reasons that I mention in the article.  

[Mike Vaccaro]

It's also a good time to check the tank for corrosion.  Pitting corrosion is common in 5000 series alloys in a marine environment.  We didn't find the corrosion in our tank until AFTER we cleaned it.  Turns out the gunk in the bottom of the tank was effectively blocking the small holes!  Go figure...

Any aluminum tank can be "alodined" and, if desired, painted to prevent surface corrosion from forming on the OUTSIDE of the tank.  Alodine is a trade name for a chemical etching process that uses a two-step acid wash to oxidize the surface of the metal.  These type of coatings can be obtained from an automotive or aviation paint supplier.  While they merit health and safety precautions during use, no special skill is required for application.    

Recommend a thorough leak check BEFORE you install any tank back in the boat.

Replacement tanks are of a better quality than the original late 80's vintage tanks.  They are made of heavier gauge metal, have a better weld and are 100% aluminum (older tanks used dissimilar metal in the fittings).  If there is any doubt about the integrity of the tank, a direct replacement can be obtained for Catalina for about 250 dollars.  

Cheers,

Mike

[Paul Blumenfeld]

Buying a new tank for $250 sounds like a good idea.  I was charged that much for someone to "polish" my tank this summer.

[Ron Hill]

Paul : You got it right on the $$.  Most fuel polishing companies want $200 to "clean" the fuel.  That doesn't get the all of the CRUD off of the bottom and sides of the tank.  Also consider the cost of Racor filters at $25 a pop.  
You made the correct decision - just buy a new tank!!