gas tank cleaning-- do I need it and how?

[msmith10]

I suspect some time this summer I'm going to have to bite the bullet and clean my gas tank. It's 32 years old, aluminum, and I suspect has never been cleaned. I have occassional fuel related shutdowns, which I can overcome temporarily with the priming bulb, and less temporarily by changing both my water-separator filter and my inline filter, the standard Racor and Moyer filters. I don't know for sure that the tank needs cleaning, but the only opening big enough to use to inspect it visually is the fuel guage cutout, which I could only see into by removing the tank anyway. Also, my compulsiveness will lead me to lay awake nights imagining that the tank has 2" of varnish and crud in the bottom until I can prove otherwise. I think I can get the tank out without removing anything hard to fix, but I won't really know until I try it.
Now for the hard part. Gasoline vapors scare the !@#$ out of me. My plans are to run the tank pretty well empty, drain the rest, remove the tank. Any suggestions for safely cleaning the tank if I get it out? Should I rinse it with water first, non-pressurized, to eliminate the risk of explosion, then pressure wash it? Acetone? I've read that old car buffs take them to radiator shops for a boil-out.

[ghaegele]

Mark, a few years back we started having fuel related shutdowns with our 1972 C&C35 that we traced back to crud in the tank. Apparently, prior to ethanol, gasoline would form a varnish-like coating on the tank that trapped all sorts of tiny bits of metal and sand and stuff that had laminated up over the many years of service. Then, when ethanol gas was introduced, which is more of a solvent than straight gasoline, it delaminated the coatings of varnish and set the stuff free.

We drained the tank into portable gas cans, then cut the old straps that held the tank in and wrestled it out of the boat. By maneuvering the tank around I could pour out most of the crud inside. Then, using hot water and orange cleaner--I think a 1:1 ration, I poured the solution in through the opening and rocked the tank back and forth, swishing it around inside. I drained it into a pail and repeated about 4-5 times until I was getting no more particles out. (I let the solution sit for a minute and then poured it off the crud and reused it.) You have to be thorough as there is, at least in my tank, a baffle in the middle that prevented an easier rinse. I probably did have about an inch of crud at the bottom of the tank!

Finally a hot water flush and the tank was pristine--mirror-like--inside. The citrus cleaner worked wonders and is environmentally a lot friendlier than petroleum based solvents. Good luck,

Greg

[msmith10]

Thanks, Greg. That's probably what I'll try. I'm going to make some rough measurements this weekend to see if the tank will come out thru the sail locker. If not, the only alternative is to pull the engine, and I won't do that unless I have to remove it for some other reason.