Aluminum gas tank leaks

[MinUph]

I have an aluminum tank under my rear sun deck that has a leak. After pressure testing I see it is at the top where a sending unit would be. This is just a cap screwed into the tank with a gasket. No sending unit is there. I cannot remove the screws they are stripped in the threads and just spin. My question is seeing this is not really a below deck tank and is ventilated well. Would it be advisable to epoxy the cover to seal the leak permanently? I am looking into a new tank but the cost would be much more than the epoxy gas tank repair. If this were in a bilge I wouldn't be asking.

 

[MH Hawker]

Re: Aluminum gas tank leaks

I would remove the old screws and retap them to the next bigger size, and often with old striped screws you and take a small thin blade of a screw driver and start it under the head of the screw and get it to turn out and the threads are shot any any way but it will come out most of the time.

 

[MinUph]

Re: Aluminum gas tank leaks

Been there done that
I even had vise grips on them and prying the plate up at the same time pulling on the vise grips while turning.

 

[MH Hawker]

Re: Aluminum gas tank leaks

WOW...The only other thing I could think of is continuous flood with nitrogen or CO 2 to eliminate the fumes. Then you can grind them off or drill them out. and I would still be very hesitant to do that. i think I would make some sort of a cap that would go over the existing one. Or pull the tank off and fill it with water. But I think I would try JB weld instead of epoxy first. JB sticks to alum real good.

 

[MinUph]

Re: Aluminum gas tank leaks

Thanks Jim,
I never thought of JB Weld. I will try that. I figure on covering the hole thing with it. I doubt it will leak there. Pressure test after to be sure.

 

[5150abf]

Re: Aluminum gas tank leaks

Scuff it super good with heavy paper like 80 grit, tehy also make a gas tank sealer somewhat like JB but made for gas, being on top of the tank that should work really well.

 

[MinUph]

Re: Aluminum gas tank leaks

I was looking at the gas tank sealer at Auto zone. It was an epoxy stick. I wonder which one would be better that or JB weld? The ank is out and I will clean the area very well with coarse paper and acetone before I put whatever on it.

 

[MH Hawker]

Re: Aluminum gas tank leaks

Well JB will stick good to alum but I didn't think about gas bothering it. and I am not sure if you need to pressure test it the tank should be vented and wont hold pressure and the flexing may crack lose the epoxy.
I just had a thought. Why not use both. I will explain. I often worked with oil bath transformers and those are about the nastiest things you can ever try to seal and you have to do it while their full of oil. We had a special epoxy that would seal however it would start leaking back in a week or two and to solve it after the epoxy was applied we would back it up with JB to add mechanical strength and it fixed it.

 

[MinUph]

Re: Aluminum gas tank leaks

I thought I replied to this last night but it must not have saved properly. I run into this from time to time here.

I read about JB Weld and it is impervous to gasoline. I will be using it tomorrow on the tank.

 

[MinUph]

Re: Aluminum gas tank leaks

Well we finally got the boat back in the water only to find gas dripping off the rear deck. Suffice to say the leak wasnt where I thought. Ordered a new one when we got home.
On a seperate note. My lights and horn allways worked. I went for a CGA inspection ths morning and no horn or lights. Wouldn't ya know.

No boating this week end. That sucks. Great weather. I suppose we could row :facepalm:

 

[MH Hawker]

Re: Aluminum gas tank leaks

sorry to hear that. I would look real carefully at lines and clamps then.

 

[MinUph]

Re: Aluminum gas tank leaks

Its actually seeping out of the bottom. I have is set up on sawhorses and I can see small spots of gas on the bottom. It is history. I never thought this would leak through the aluminum.. I don't see any holes.

 

[jeeperman]

Re: Aluminum gas tank leaks

gasoline will leak thru a hole or crack that water will not, just because gasoline is "thinner" than water.

 

[MinUph]

Re: Aluminum gas tank leaks

I knew that but never put it together. Interesting fact. I won't need to worry about it with the new tank. Shipped out today

gasoline will leak thru a hole or crack that water will not, just because gasoline is "thinner" than water.