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-   -   Life expectancy of aluminum diesel fuel tank (http://www.sailnet.com/forums/gear-maintenance/48386-life-expectancy-aluminum-diesel-fuel-tank.html)

jbrockpiano 10-27-2008 11:32 AM

Life expectancy of aluminum diesel fuel tank
 
I have an Islander 30 built in 1974. The tank is original and does not leak at this time. The tank has had a cleaning/inspection port installed in the top but the rest of this 30 gallon tank is glassed in place under the starboard quarter berth. The tank has some some issues in that the main feed line to the engine is connected to what used to be the return. What used to be the main feed with the fuel cut off valve still attached has no siphon tube connected to it and now only serves as a return.
My question is: Should I attempt to repair the plumbing on a tank that is this old or should I be thinking of replacement ?
Thanks for your ideas.

bubb2 10-27-2008 11:44 AM

This is one over best questions ever posted on sailnet. I going to start by telling you I don't have a good answer. Aluminum tanks are known to leak at the welded seams as over the years water gets in to the weld and causes corrosion and the weld fails. It happens more with aluminum water tanks, But can happen with fuel tanks as water is next to imposable to keep out of the fuel and sits just below the bottom of the fuel pick tube.

Hard call with a 35 year old tank.

erps 10-27-2008 12:14 PM

Nutz!. I'm in the same fix. Guess I'll find out the hard way.

sailingdog 10-27-2008 12:33 PM

I would recommend replacing the tank. Making a repair doesn't make sense on a tank that old, since it is likely that you'll have to repair it some time soon.

sailboy21 10-27-2008 01:02 PM

If it isn't leaking keep her going. As long as it is kept dry and was originally of sound design (which it probably was if it is still holding together) it should last a few more years at least. It will cost a whole lot of beer money to replace it. If you do any work on it don't use any brass or bronze fittings. Get monel or 316 SS pipe fittings ONLY!!! Don't even use other aluminum fittings, they are not the same alloy.

J36ZT 10-27-2008 01:25 PM

Jbrockpiano,

I'm not sure what your purpose was for posting this. I think it's obvious you need to do something before you end up with diesel in your bilge. And, using an emergency repair (ie switching the hoses) long-term probably is the best thing to do.

My boat's original diesel tank was also aluminum, built in 1980 and put into service in 1981. Two years ago it started leaking. I pulled the tank and put JB Weld over the leak and along any spot I thought needed it (inside and outside). One year later, it sprung another leak in a new place. I investigated many alternatives. I ended up having a stainless steel tank made.

I'd say your tank is near the end of its life expectancy. But, it all depends upon how well the system has been cared for (frequent fuel polishing, additives to remove moisture, quality of fuel, humidity levels, etc.).

The answer to your question: It's your choice.:D

Skipper, J/36 "Zero Tolerance"

J36ZT 10-27-2008 01:34 PM

Sorry, I forgot to proof-read well enough...

Quote:

Originally Posted by J36ZT (Post 391186)
Jbrockpiano,

....And, using an emergency repair (ie switching the hoses) long-term probably is the best thing to do. ...

Should read: ...isn't the best...

Wow, the trouble one can get into by forgetting two letters and an apostrophe.

Sorry,

Skipper, J/36 "Zero Tolerance"

Rockter 10-27-2008 03:26 PM

If the leak (in the future) is at the bottom of the tank, and you can get access to the top of the tank, it is not difficult to fix it. Purge the tank, clean the floor of the tank like crazy and apply a two-part polysulphide adhesive in there. Mine has lasted 10 years since the repair.


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