When I fill the screen wash bottle on my W124, it's entire contents seems to empty over night via the headlamp wash wipe nozzles. I've replaced both nozzles with brand new parts from the dealer and this hasn't cured the problem. All the hoses checked, and are all fine. So, the only remaining culprits are the washer pump and the non return valve that splits the water from the pump into the two hoses that feed each headlamp. Having taken the washer bottle out of the car with the motors still in place, I filled the bottle with water, which proceeded to empty via the connectors on the rear of the pumps that feed the windscreen and headlamp wash respectively. Is this normal? I was expecting the water to only come out of these connectors when the pump was operated? I'm not sure which part to change first. The non return valve, or the pump(s)? Any thoughts?