In all but the coldest times of the year it is best not to fill the tank to the 'brim', as the diesel is stored underground where it is usually cooler than inside the car's tank. Normal temperature difference expansion can cause this kind of pressure, IF the tank vent is plugged. This vent is located, if I remember correctly, forward of the rear wheel on the drivers side. It is a rubber hose ending in a small bell shaped device.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150