Aluminum Fuel Tanks

Hi All Owners , Has anyone looked inside their diesel fuel tanks , recently ?

My BCC is a 1985 vintage , I installed two inspection plates in the aluminum fuel tank , first to swamp out any fuel sludge and water , in an effort to avoid sudden engine stopage during port manovures .

What I found was that water droplets had contacted the aluminum tank floor and pitted it .

Of course I moped out that water and a small amount of diesel sludge , but did notice that the tank bottom was rough and pitted where the water droplets contacted it .

After that , there seemed little that I could do , I have continued to watch, (once a year) to see if any further pittimg or corrosion was evident !

Since I have not noticed any further tank bottom pitting , I suspect that is because there is no further condensed fresh water or “Salt Water” has entered the tank .

I don’t know how deep the old pits are in that inside surface . Although brown discolored , the tank sides , appear smooth and un-pitted .

Using a face mirror , to inspect the inside welded joints , there appears to be no pitting or corrosion anywhere in the tank , otherwise on the tank floor .

I did wish that our tanks had a water trap on the botton that could be drained , but alas , that must have been an expensive option .

I’ve had my tank out, inspected, cleaned, and an expansion added on. I didn’t see any of the signs that you’ve described(1980 hull)except for discoloration which was surface residue and easily cleaned out. I did have pitting on top of the tank from moisture sitting unnoticed. Depth was about 1/4 thickness and didn’t worry me. I thought about adding a sump as well but in 8 years of buying fuel in questionable locations, we’ve only had one problem and I could blame myself for that(the one problem almost cost us the boat). I did make a habit of pumping out the bottom of the tank about once every year or so using a drill powered pump with an extension to get to the bottom. I didn’t empty the tank for this, just pulled the bottom residue out. Have to say that I never saw much accumulation of anything worrisome during this time. I did use fuel treatment when getting iffy diesel. Cheers, Ray