The car is an Astra Estate 1.6, 16-valve with the 'Ecotec' engine. I have been told it is a Mark 3; the year letter registration is R.
There is a small split (about 0.3 inches long) in the bottom centre of the petrol tank: that surface of the tank that is horizontal and parallel to the road surface. (How the split occurred, I have no idea - not that that matters now, anyway).
To repair this, I have tried "Petro-Patch". I started with the tank completely empty. I thoroughly cleaned the metal surface until it was immaculately clean and then slightly roughened it with Emery cloth to provide a good key. I carefully mixed the 'Petro-Patch' compound (as per the manufacturer's instructions) and applied it to the affected area and left it for 72 hours to cure. Then I put about 10 litres of petrol in the tank. At first, no signs of leaks. But two days later, it is leaking again. It seems to be coming through the "Petro - Patch" compound, rather than seeping from around it, due to poor adhesion of the compound to the metal surface of the tank
So "Petro-Patch" doesn't seem to work (which surprised me ) So - has anyone here any suggestions of how I can fix this leak? - apart, that is from replacing the tank (expensive! )