Petrol tank issue

[Pjr]

Hi all, I've done a search of the archive but I haven't found what I'm after. My boot has always smelled of petrol so I replaced the long breather. All other pipes and joints seemed dry, as did the pump. This evening, I noticed a damp/ wet patch on the far right end of the tank - the felt insulation under it was wet with fuel at the bottom seam facing the suspension turret.

My question is whether there is a potential innocent source of the leak, or does this mean that the tank has rusted through? As far as I can tell, there is no leakage around the filler, or the fuel level sender (but I couldn't get my hand right in to feel) and in all other respects the tank looks very nice. When I look into it from above, the bottom is not rusty, but I suppose it could have stood with water pooling in that bottom corner which I can't see!

Any wise words appreciated.

[Pjr]

This morning there was an actual puddle in the boot so I have just done an emergency drain down and the tank will be out shortly.

Assuming I have a leaky seam or perforation, had anyone tried POR15 tank sealant or similar?

[Pjr]

Hmmm, drivers side bottom 1/3rd of the base is rusty and the seal seems to have had enough.

May I draw your attention to the wanted section.....

[fueltheburn]

Mild steel tanks. They rust more when left standing empty over winter.
A stored car should have a full fuel tank that is then drained down and re-filled with fresh fuel before car is used again.

Fuel injection uses the original tank as well. Unless like Pete B - you have an aluminium one.
Something I will be doing at a later date as well, to ensure the longevity of my fuel tank as well.

[Pjr]

I guess it is 31 yrs old, so I can't complain. I think meths makes the water miscible (or something like that) in petrol, so perhaps I will add an additive in future to remove any condensation. I suppose it's all part of getting to know the car inside and out.....