I have 2 150 gal aluminum fuel tanks and while they are out of the boat I want to clean/flush the inside of them. The fill neck is curved so cant get in there and the sending units are 1.5 in in dia. so not much room there,they are 27 yrs old and just want to make sure they are clean.. Has anyone every cleaned there tanks if so how did you go about it what did you use. I had people say take them to a radiator shop..they are about 6 ft long and 18 in square I havent seen a radiator tank that large before...any ideas ?? You have to remove engines and trans to get them out of the boat so I want to do this only once. Thanks Jamie

Put a bunch of nuts and bolts in the tank, be sure to count how many you put in. Strap it on the back of a ATV,sideways on the back rack and find the bumpiest field to ride through and do a lot of turns. Fish the nuts and bolts back out and flush tank. Works real good to remove the white corrosion in the tank.

You wouldn't happen to have a video of that on youtube?

Pure ethanol, fill gas tanks about 60 % full and drive the gas tanks around back in your pick up for a couple days to make a washing machine effect inside the gas tanks.

Next is acetone but it can get expensive depending on the size of the gas tank, do the same for the washing machine effect

high pressure power washer and using the wand and possible wand extensions

Take it to a radiator shop

Take it to a place that ultra sonic cleans very large parts.