For those with older aluminum fuel tanks

[robertsapp]

Just thought I'd pass on a recent experience of mine. I pulled the 30 gallon aluminum fuel tank on our 1995 H336 to install a clean out port and do a thorough tank cleaning. Before ordering the cleanout port, I put the tank on my workbench and did a pressure test by filling it with soapy water, applying pressure for an hour with the discharge from a small shop vac, and checking for leaks. Everything seemed fine. When I cut the access hole in the tank and cleaned out the accumulated goop and crud in the bottom, I found numerous deep pits in the bottom of the tank. Many were so deep there couldn't have been more than the thickness of a sheet of paper left in the tank. It was basically a ticking time bomb, on the verge of perforating and draining my fuel to the bilge. I took it to a local welder, who charged me $200 to weld in a new bottom. So if you have an older aluminum fuel tank that you've never been in, beware!

 

[ggrizzard]

Seems to me you could buy a new tank for $200 clams, I did.

 

[robertsapp]

Seems to me you could buy a new tank for $200 clams, I did.

If I was willing to settle for a much smaller tank. None of the "off the shelf" models of similar capacity would fit in the available space, because the tank sits in the aft port corner of the boat and is trapezoidal in shape. I could have gone with a rectangular one of 12 to 18 gallons, but I wanted to keep my 30 gallon capacity. If you know of a welder that will manufacture a trapezoidal aluminum tank with welded vent and fill connections, welded outlets for fuel supply and return lines, and two weld attached mounting brackets and a grounding tab, all for under $200, please send me his name, I have some work I'd like to get a bid on.

 

[Alex Dare]

re-installing teh tank

When you replace the tank, try and put some appropriate spacer strips under it. What often happens is that the the tank can sweat or for other reasons moisture accumulates between the bottom of the tank and the plywood shelf it sits on causing the corrosion.

 

[robertsapp]

Re: re-installing teh tank

The corrosion was on the inside. The outside looked fine. The point of my post was that the tank looked pristine, and passed a pressure test, it was only when I opened it up that I discovered it was on the verge of perforation from multiple pits. So I'm warning everyone with aluminum tanks that if they're 10 or 15 years old, just because they look fine doesn't mean they're not ticking time bombs.

The tank originally sat on 1/4" neoprene strips, which I replaced with new ones.

 

[Ed Schenck]

Ten or fifteen?! Three aluminum tanks, all near 50 gals and 32 years old. And all inaccessible without cutting fiberglass. And probably leaking.

 

[Don Guillette]

I agree with Robertsapp. My first clue that I had a problem with a 13 year old fuel tank was when I smelled the fumes. I knew I had a problem but ignored it until my wife refused to go to the boat. Shortly thereafter I found a little diesel in the bilge - not a lot but a bit of shine on the water. I ignored that also because it was a small amout of fuel. Next I found a pin hole leak in a corner and realized I have to pull the tank but I had a full tank, which had to be pumped out. There were 4 phillips screws holding it in place - three came out easy (like I knew they would) but the 4th one, which was in the worseplace, I stripped the head. Finally, I removed the tank and took it to a tank fabricator in Orange County, Ca to be pressure tested hoping I had only only one leak to plug. No such luck. I had pin hole leaks all over the tank!!

I had them build me a new tank for about what it would cost me to buy one from whomever. The advantage to me was the new tank was an EXACT duplicate plus the hold down pads were in exactly the same place as the original.

The bottom line of this story is if you have a boat over 13 years old with the original tank you're on borrowed time and as soon as you first smell the fumes plan on pulling the tank and replacing it because things just are not going to get better. The stink of diesel is a sucker to get rid of.

 

[robertsapp]

Absolutely with you on the stink being hard to eradicate. While our tank hadn't started leaking yet, there had apparently been a leak at the fuel return line fitting that the previous owner hadn't addressed, which had allowed some fuel to accumulate behind the rear cabin partition. After yanking the tank and having the new bottom welded in, we spent an entire weekend taking everything off the boat (cushions, soft goods, emptying all the lockers and pukas, etc.), scrubbed every surface with citrus boat soap, and then followed Peggy's recommendation and filled a pump sprayer with a gallon of PureAyre and sprayed all surfaces, then closed up the boat and let everything dry. We kept the berth and setee cushions at home for about three weeks, spraying them regularly with PureAyre and sitting them out in the sun on the patio whenever possible. Finally, we have a nice fresh smelling boat. The wife is happy again, so life is good.