[bikz]

guys,
i had a strong fuel smell coming from my tank whenever i pumped a full tank....so when i took her in for the major, they told me that the tank was leaking.....so got the tank out and i personally cleaned it with loads of detergent, dried it, air cleaned it and took it for welding.....(not many guys weld fuel tanks i found out .....found the guy who was sure there was no more fuel vapour inside and got it welded).... the pix shows the trail the petrol had been leaving from the leak, and upon scraping of the silver paint, found the pinhole quite straightforwardly.....

this is my theory of why the leak came about....if you guys have read of the famous imploding tank in the other forum,mine kind of expanded/"exploded" .it looked like the pressure built up in the tank as there were slight bulges in the tank and one pinhole as a result of this pressure build up....this is what i think happened, my car had been sitting idle for about 3 years before i got it (besides the occasional engine warmups)....this is another example of why cars should be on the road rather than sitting in garages idle....i suppose the 2 way valve (turn over valve) which releases the built up gases has malfunctioned a bit...i havent gotten to it to check the valve yet though..so the pressure built up to a point where it made a pinhole for the pressure to escape and the leak has been from there.....
however my mechanic also has not ruled out on the fact that the hole could be due to vibrations on the tank and the tank having rubbed on some part of the car as the area where the hole was ( and some other areas as well on the same side) seemed to have had some of the silver paint having rubbed off due to vibrations or something.....any idea? i think however these minor scrapings happened when the tank was removed from the car.....

[a1exander]

Interesting.
The "pin prick" hole is unlikely to have been caused by vibration although I am equally at a loss to propose an alternative cause

[Saint Bastage]

SERIOUS amounts of corrosion on the external surfaces of that tank. It looks like a casting in the pictures. Localized corrosion on a surface such as that indicates oxygen pitting caused by long term exposure to moisture and oxygen. Very common in boilers. I've never looked closely ay my tank. Is there an insulation blanket over it or some other things that could hold moisture over a long period of time? Consider a media blast, perform a light pressure test, clean it well, and give it a nice paint job with a rustoleum type paint.

[tazandjan]

Most of those pinholes are caused by rubbing on the mounting pads or straps. Incidentally, most welders who are working on fuel tanks fill them with water first. Prevents explosions.

[cribbj]

Originally Posted by Saint Bastage

SERIOUS amounts of corrosion on the external surfaces of that tank. It looks like a casting in the pictures. Localized corrosion on a surface such as that indicates oxygen pitting caused by long term exposure to moisture and oxygen. Very common in boilers. I've never looked closely ay my tank. Is there an insulation blanket over it or some other things that could hold moisture over a long period of time? Consider a media blast, perform a light pressure test, clean it well, and give it a nice paint job with a rustoleum type paint.

Lane, I think what you're seeing there is the spray on insulation coating that Ferrari put on the tank. It has to be ground off to get the tank down to bare aluminum. The tank in my 550, and the spare I bought awhile back both look like that.

[Saint Bastage]

Didn't know it was aluminum. That certainly makes a difference. Forget my comments about Oxygen pitting. That only applies to carbon steels.