Diesel Tank Cleaning

[boatless 4 now]

Hello all,
Happy new year.
I have a 1990 Catalina 30 that has not had the diesel tank cleaned in quite a while. Looking at the tank, there is no inspection cover, only a small gauge and the hoses. How do I go about either cleaning this tank or cutting an inspection hole that I can use and replace for future cleaning. Has anyone done this or had this problem?
Thanks for the help

[gonesail]

any cutting and drilling done on the tank will result in lots of metal filings that you will need to clean out as well. i would use a hole saw on a heavy duty drill to do the work. the seabuilt company out of seattle makes a really nice inspection port. be sure you know where the baffles are cause you can't cut there. then you can drain your tank and clean it out in style.

[Ziggy]

It depends on the construction, material, and condition of the tank. Depending on the answers, it may be more practical to replace than to clean.

[Ziggy]

Also, how do you know that it needs to be cleaned in the first place?

[John A]

Originally Posted by Ziggy

Also, how do you know that it needs to be cleaned in the first place?

You'll know that it needs cleaning when the fuel pick-up tube becomes clogged!! Another indicaion is when you need to change the fuel filters more often than normal.

Prior to going cruising, one of the most important 'to-do' projects is to have an inspection plate installed on all fuel tanks, and the tanks steam cleaned by a professional service.

[Ziggy]

Originally Posted by John A

You'll know that it needs cleaning when the fuel pick-up tube becomes clogged!! Another indicaion is when you need to change the fuel filters more often than normal.

I agree, however the OP has not mentioned either of these conditions. And I still stand by my assertion that, depending on its condition, it may be more cost effective to replace the original tank than to try to add an inspection port and clean it.

[jdoe71]

I've done this with two boats, Catalina 28 and now our 36. I took them both to a rad shop that does this work. They clean it using a variety of wands made to get in through the fuel gauge hole, the filler, vent and fuel line holes and whatever other holes exist in the tank. They put a new gasket on the fuel gauge sender when done. They use mechanics mirrors and small wand mounted lights to see inside the tank. Both tanks were spotless when done. Cost $75. Judging by the fuel that came out of the bottom of these tanks when I pulled and drained them, it was money very well spent. The fuel tanks are so easy to remove and the cost so minimal I intend to do this on a 5 year basis, I prefer to be proactive about maintenance rather than waiting for the engine to die and discovering that a problem exists. I will wager there is a rad shop somewhere in your area that does this, or a company that specializes in fuel tanks given that you are near a bigger center than the boonies where we live.

[Mark Zarley]

Fuel tanks get water in them from condensation. This leads to algae, which leads to a Mud Dobber (wasp) type deposit, that is "acidic" and will eat it's way through metal tanks and aluminum (much faster). We turn over our fuel 4 or 5 times per year but because of extended periods when some of the tanks are only 1/4 full we get condensaton. I clean my tanks every 3 yrs, draining all but a couple of gals. Using a long handled squegge I am able to use the fuel to cut the asphaltine on the sides of the tank and scrub the bottom. Soaking up the remaining mess with paper towels. Fresh air circulation is impt as concentrated diesel fumes is bad for the lungs. Would not steam clean as disposal of fuel water mix is difficult , and why add more water to a water problem. Most tank cleaning services only polish the fuel then finish the cleaning by hand through insp ports. You can make your own inspection port, (backing plate , cover plate and gaskets) I made oval ones. I would first determine the condition of your tank bottom then proceed from there.

[syoder]

I did just what you're asking about on my Westsail 28. Cut a fairly large )about 6" x 9") rectangular hole in the top of the aluminum tank using a scroll saw after making an initial hole with a drill. Bought a piece of 1/4" aluminum plate from a local welding shop that was about 1/2" larger all around than my hole to use as a cover. Drilled holes along the perimeter every inch and a half or so. Made a gasket from some rubber sheet and used self-tapping stainless screws dipped in Lanacote to hold the cover in place. As it turned out, my tank wasn't nearly as dirty as I thought it would be after over 30 years of use. Could have easily gotten by without cleaning it but I'm glad I now have an inspection/cleaning port.

[Sonrisa]

Another option is to find a company who offers remote fuel polishing services. There are a few in my area, they can't be too uncommon. They'll have a unit which they can roll right down to the dock, then clean out the tank using small hoses/wands by cycling the fuel through again and again, filtering it each time.

[Mark Zarley]

Fuel polishing is but one step, the impt step is to clean the asphaltine from the sides(it builds up and slides down the sides to pool on the bottom) The wands are a hit or miss situation and cannot compete with a manual washdown of the inside of the tank and a visual inspection of your tanks bottom. I had my fuel polished down to 2 microns after a bad fuel stop . Pulled the insp ports 4 months later and there was still plenty to clean up.