Hans, above the fuel pump gear cover is your water pump, it has a pulley on it ran off a belt, your fan is bolted to it. Behind that pulley is a bearing pressed into the pump that the shaft rides in, it has a seal behind it. When the seal blows coolant gets into the bearing, and a hole is provided in the pump housing for coolant to escape to tell you coolant is getting to the bearing. It's the water pumps way of telling you it needs to be rebuilt or replaced. All cars and trucks used to be built this way, 99% still are. Some have electric pumps now for performance or mileage reasons.