hard to find I/O fuel leak

[gregpatent]

I have a 1985 Glastron I/O with a 30 gallon aluminum gas tank. I filled the tank for winter storage, and sometimes when I pull the boat on the trailer, I find traces (about 1/4 cup) of fuel in the bilge. The filler hose, vent hose, and supply hose are either new or look okay. I also do not feel any wetness on the connections to the tank, the water separator, the transom vent, or low points in the hoses. Is there a way I can safely find the leak without removing the tank and visually inspecting its entire surface, which requires me to remove a portion of the deck, not to mention 30 gallons of fuel? The boat is primarily used in salt or brackish water, and I am not sure how aluminum tanks do over time in such environments. However, if I had a leak in the tank, it would seem that it would be in the bottom where it contacts bilge water and that I would have more fuel in the bilge than 1/4 cup. Any suggestions?

[jimski2]

A full gasoline tank can cause a leak at the fill hose when the boat is raised to drain the bilge through the transom plug. This happens with a "full tank" as you have noted. If the hose is old [1985, 25 years] and hardened you need to replace this hose. Our E10 gasoline also dissolves older rubber hoses and they should be replaced. You might get by with just tightening the two clamps on the hose you should have there. Remember a cup of gasoline has the explosive power of a stick of dynamite. Be careful, no sparks, pull your plug and ventilate well. Newer boats have the fill hose in the front of the boat to cover up this potential danger. Raise the front of the boat up high and see if more gasoline leaks out.

[gregpatent]

Thanks for replying -- I'll try it. The fill hose is old but doesn't have any visible cracks. I believe it's expensive, but certainly cheaper than blowing myself up.

[big easy]

I can tell you that from all the saltwater boats that my friend owns and many others that he has completely restored,and sold material for,that leaks and corrosion on aluminum tanks in salt water boats is extremely common.

It's extremely common to get tiny holes in areas of corrosion in the aluminum.The corrosion leads to leaks that are so small that they are hard to see.The leak can be so tiny,that they only weep a minute amount of fuel.

It won't be that way for long,and it only takes a trace of fuel to cause you to get a free rocket powered amusement park ride when you turn the ignition key.

I recently restored a 30 yr old boat,and when we removed the aluninum tank,we found a lot of pitting where the aluminum was eroded about half way through.I pressured tested it,and fortunately it was ok,but if I hadn't removed it and not cleaned off the corrosion, failure was probably only a couple years away.

If you can't find any leaks in any of the hoses,than it's time to pull the tank and either pressure test it,or examine it extremely well.

If it's a leaker(even tiny)don't attempt to try and fix it.replace it,you'll be much better off,and remain alive.

With my tank,I was able to remove all the corrosion,and clean and dry it,then gave it a coating of epoxy barrier coat.Now that it's only in fresh water it should remain solid.

The corrosion starts when the tank remains constantly wet or damp because air can never get to it.Being where they are under the deck it's the reason it happens,and saltwater is much worse on aluminum.

If you replace it,make sure it's elevated off the bottom enough so that water will not stay in contact with the tank.

Here's a good technical article on how to replace a tank,lots of do's and don'ts

http://marinesurvey.com/yacht/fueltank.htm

[gregpatent]

Thank you everyone for your helpful suggestions. I removed the tank and found the leak was caused by a deck screw puncture in the top bow end of the tank, which is why it only leaked when the tank was full. A former owner installed a 1x2 over the bow end of the tank and screwed a deck screw into the top of the tank. When I turned the tank on its end, the gas remaining in the tank poured out of the hole.

I am weighing whether to patch the hole by JB Welding a small piece of aluminum over the hole or buying a new tank, provided I can find one at a reasonable price that comes close to fitting the hole. Other than the puncture, the rest of the tank, including the bottom, looked okay. All of the hoses need replacing. The filler hose was dated 1984, the same year I saw my first Yes concert.

[jimski2]

Welding a gas tank is usually not good.

[L&M]

Marine - Tex will work as well if not better than J-B weld if you take that option. Make sure the surface is clean & ruffed-up well around it.