1981 240D, Diesel is spilling down the side of the car out of the tank (I know, it’s not a gas tank). I did the obvious and replaced the fuel cap, but that didn’t help. I’ve seen a number of W123’s on the road with the right rear quarter panel covered with diesel.

Any thoughts?

Thanks

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1981 240D Four on the floor, Orient Red over Parchment, bought with 154,000 but it's a daily driver and up to 180,000 miles, mostly original paint and all original interior.