Saugdüse :-)

[Jon B]

As long as I had the dust cover off my car, I thought I'd inquire about this...

My VDO washer fluid reservoir has a hose that enters through the cap. I rarely see this in other photos.
It's shown in the orange books, illustration #5 below, and described as Saugdüse, or suction nozzle. Hose #4 was merely spare hose, sold by the meter.

It's unclear from the book, but this seemed to be original on all models except the 2,5 and those cars with headlamp washers.
Is this true?

 

[Thomas76]

I've got a couple old caps floating around, neither have holes in them.
Hydraulically speaking, the only thing it might do is allow the lines to drain to tank.

 

[Markos]

I've got a couple old caps floating around, neither have holes in them.
Hydraulically speaking, the only thing it might do is allow the lines to drain to tank.

Curious. I saw this in @whalem6 ’s ad. It’s not for headlight wipers. The HL wiper tank has an extra nipple on the bottom. My guess based on his photo is that early tanks had only one nipple on the bottom and that tube from the top. My initial thought was that it is a breather but that doesn’t explain the tube. Probably easy for someone smarter than I to determine from the pic below.

Also, this Alpina CSL had no HL wipers:

Photo credit @whalem6

 

[HB Chris]

Based on the diagram it sends some fluid back to the tank as it branches from the hose to the wash nozzles.

 

[Stevehose]

My car had it when I got it

 

[Jon B]

Curious.

Markos, yes I've been curious about this.
For instance, of the last 32 cars on BaT, only 1 has had a hose through the cap- the 72 Baikal car from Tacoma.

 

[deQuincey]

I've got a couple old caps floating around, neither have holes in them.
Hydraulically speaking, the only thing it might do is allow the lines to drain to tank.

hydraulically the hole in the cap will allow air into the reservoir when you use your windscreen water, a 100% airtight reservoir will be more difficult to work with

 

[Arde]

Or it serves as a poor man pressure regulator? Let's say the electric pump varies widely in pressure, this feedback loop limits the pressure to the nozzles?

 

[Cornishman]

Wild guess as I can’t see the images well. Blocked nozzle protection, if feedback loop has a restrictor that would help to restrict max pressure?

 

[Arde]

I checked my CS and I do have the hose!
Saudguses über alles!