I am putting my windshield washer tank (back of front passenger fender) back together after removing and cleaning it - it had a soupy mix of coolant that was rancid. While looking at the parts diagram, I noticed the second smaller tank (located up by the window) is connected to the system washer system (windows & headlights).

Does anyone know what the point of the second tank is in the system?

Thanks,
Dave

 

The tank near the windshield is for the intensive washer system. This is a secondary washer system that was filled with silicon remover fluid.

This is very helpful on long Autobahn or Freeway trips, when the windshield has to be cleaned of bugs, oils and other stuff that won't come off with the regular fluid.

Valves in the hoses connecting to the nozzles ensure that the fluids don't mix.

The intensive washer system was discontinued in 1994, when Porsche started installing interior air filters in the 928s.

 

if you need to know how the washer system is routed just look at the PET .
When you refit the tank make sure to remove both of the metal collars, one in the tank and one in the fill spout