Windshield washer backflow? Huh?

The San Diego region, and SouCal in general, can always use some rain so yesterday morning I went about thoroughly cleaning my windshield and fixing my windshield washer system on my Nissan pick-up. The washer was down to one weak stream on the driver’s side and I took that as a sign that I should maybe address fixing the on-board squirt gun devices.

It went in a straightforward manner: I replaced the old hoses and removed the squirt guns from the hood. As I suspected they were clogged with come sort of blue calcification crap and used a 0.020" wire to clean out the openings and the manifolds. Replacement went fine and they now work like little charms.

Funny thing was that there were three back-flow check devices in the washer lines. they needed cleaning too but were easily cleaned. One was just downstream from the washer fluid reservoir and the other two maybe three inches upstream from the squirters themselves (i.e., just under the hood). They was nothing in my Haynes manual about them but I found a website that mentioned such things as components in a washer system.

My question is: What the heck are they there for?!

I would have thought it would be a good thing for the washer fluid to siphon back down to the reservoir so there’d be no water in the lines to freeze up when you would need the washers the most. What gives?

It’s not good for the fluid to drain back out of the lines because then there’s a significant delay in getting it to squirt out when you need it. Freezing in the lines is not a concern in that a) washer fluid has a freezing point of -20°F, and b) it can freeze in the reservoir and in the pump – there’s nothing special about keeping the lines clear that’s going to prevent the problem.

Thanks Gary for the quick response. Now about that power steering… :wink:

On that subject, most of my colleagues call a power steering fluid flush a “wallet flush.”

One other reason for the backflow valves surely is to protect from freezing. If the system drained back and you got water down there from rain or slush, it could freeze and break the nozzles. They certainly would be clogged. So it’s best to keep the system primed.

small pumps aren’t self priming, they need fluid in the pump to work. the valves besides providing an instant squirt as mentioned also keep the pump primed if the pump is midway.

My old car would always run out of washer fluid, even when I knew I hadn’t used the fluid. I eventually realized that when I accelerated, fluid would dribble out of the sprayers. I’m wondering if perhaps they are supposed to help with that, as well (but didn’t in my case).

Well that’s not very encouraging seeing as I was going to tear down my PS unit and find where it’s leaking. It’s OK, though. I’m a pretty good wrench and the pump and actuator are pretty accessible.

Though let’s face it: I’m screwed.