Why not just one check valve at the windshield washer pump?
 

So I'm bored and waiting on some parts before my engine goes back in... I decide to look into the windshield washer system because it hasn't worked since I put the car back on the road a few years back. I know.. me and my silly "easy button".. but seriously, one check valve at each nozzle? Why not just one right at the pump? It would serve the same purpose and prevent flow back to the tank. I know some have done away with the check valves entirely but that makes the pump draw longer to get the water flowing. I figure one at the pump holds pressure on the upstream side and prevents siphon back to the washer tank.

What am I missing here?

I would bet that Porsche designers and engineers worked on the drain back issue for a while. Since it cost twice as much for two nozzles, there must be a valid reason of the bean counters in at the time would have said use just one.

I look at it and think "that's an overly complicated system for getting fluid on the windshield" I'm tempted to just put one check valve at the pump and see how it goes. I guess these check valves are known to fail if they go unused for a period of time or they require cleaning. Either way their location makes them a PITA to get at for any sort of service.

So I'm thinking I'm going to do some plumbing work. I think I can put this check valve in place up front at the T fitting that acts as the check valve for the driver side nozzle and then just plumb directly into each nozzle from it. I'll put a check valve at the pump and then this one up front which should act the same way the current system does but with easier access to the valves.

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While your in there, I'd suggest pulling the washer tank and thoroughly cleaning it. Mine was half full of congealed ancient washer fluid that plugged up everything including the filter at the pick-up tube. Also gives you an opportunity to clean the debris from the inner fender ledge that will rot through the fender if left unchecked.

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Belmetric washer hose info in case you hadn't seen it yet -

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Yeah I was all over the pull the tank idea. I just finished freeing up the check valves for the headlight washers (where the hell were people driving these cars!?) and making sure that the headlight pump works which it does. Tank is cleaned out and I ordered that check valve.

The funny thing is, the pickup tube (yellow in your pic) has a check valve too so I can't see how I'm going to have any issue with back flow to the tank.

check valve proximity reduces the time to squirt

zees a German automobile, ja?

I was thinking that the check valve just keeps the fluid in the line. So my thought was that any check valve in the system would reduce time to spray. System just seems overly complicated for what its ultimate intent is... get washer fluid on the windshield.

Tank is back in. I was able to get the passenger side check valve to flow. I might work on the driver side tomorrow. I have a frunk pump coming and that should be the end of this saga. Then its on to cleaning up my engine fan housing then back on with the refreshed transmission and put the engine back in. Gotta get that done or I'll go nuts with little projects.

I just went through this, I replaced the check valves the spray nozzles and the pump. In the end it was the washer hose which had been kinked, sometimes it would relax and work and other times it wouldn’t.

Check your hose, or better yet, replace it.

I thought about that so while I had the passenger side nozzle out and check valve removed, I blew some air though the hose and it flowed freely to where it would connect at the pump. I was thinking since it hadn't been used in probably more than 10 years that there would be some nastiness inside the lines.

Thinking more about this setup, in the picture of the pickup tube that Solamar posted you have the center port being the pickup. the right port goes to the vent at the fill point and the left is actually a return or vent from the spray lines if what I saw yesterday while tracing my lines is correct and that would explain the check valves at the spray nozzles. On the out side of the pump the line on my car goes up into a T fitting one side of the T goes to that left port while the other goes out and to the spray nozzles. I'm sure they had a reason for that return or vent but I can't for the life of me figure out why it would exist.

Just a guess, but would the low pressure aero effect behind the nozzles pull the fluid out of the line from the pump to nozzle if there was only a check valve on the pump?

And less fluid residual fluid to be dripped/splashed when running at speed.

A few months ago I drove down I-40 west into a headwind of a windy day even for Oklahoma. 50 to 55 MPH straight line winds. The speed limit is 75 so effective airspeed of 130 to 140 (OK, I might sometimes have to pass a semi) and there was no sign of fluid from the squirters. The vents above the rear window sounded like a vacuum cleaner as I cruised along at 3,000 RPM.

It was scary to pass semis and motorhomes as they floated around the lanes trying to stay in their lanes. I would wait for a large clearing and blast past them in 4th gear ASAP.

The drive home was very quiet and relaxing, no wind noise, and the trucks would be blown off the road and not onto me.

One of the few things I can blame on the previous owner is I have to check valves in my system. They were all removed, and replaced with just regular tees. The squirters run for a couple of seconds before water hit the windshield.

It is one of the projects that I will get to some day. It is just not much of a priority. Maybe the next time I have to replace the fresh air fan I will do the check valves.

I decided to pull my squirter tank and clean things up under there. I was surprised that when I was loosening the hold downs, it seemed like the tank was full. I siphoned the fluid out and it was clear as water. I removed the tank and poured out the remaining fluid and out comes the blue stuff. The bottom of the tank was perfectly clear and clean. I last filled it with windshield fluid 20 yrs ago when I bought the car and was driving it from Ca to Wa.

Glen,
I'll let you know how the check valve pictured above works. I'm planning to take the two off at the nozzles and install one.

Same thing with my hose, if I blew compressed air through it then it would work for a little bit, then later the kink would collapse and fluid wouldn’t go through. Please for everything that remains holy in the in the annals of DIY replace the hose. SmileWavy

Nope! I refuse to learn from the mistakes made by others! I must make the same mistake. :D

There I was, all excited about getting my new washer pump. I installed it, put 1 gallon of fluid in the tank, applied power to the pump, pump makes a sound, fluid flows from the nozzles at the windshield.... and from the bottom of my new pump :(