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Tuesday, December 06, 2005


Windshield washer fluid

Today woke up to find the Focus's windshield iced over. Unfortunately I'd been procrastinating a little bit when it came to filling up the windshield washer, and there wasn't any fluid in it. So I went and got a new bottleful today.

I also thought I'd pass along a minor tech tip, particularly for those like me who live in warm climates but occasionally have to deal with ice. Windshield washer fluid comes in many freezing points. While out shopping today, I found some rated for 32 degrees F, some for 22, and some for -20. (For those who prefer Celsius, that's 0, -6, and -29 degrees, respectively.) The lower freezing point doesn't just keep it from freezing in the winter, though - it helps melt the ice off your windshield. The lower the freezing point, the less washer fluid it takes to completely melt the ice. Some of the summer washer fluids will hardly melt ice at all.

Now that I've heard some of the newer Buicks have heated windshield washer systems, I'm starting to wonder what it would take to retrofit such a system onto a car that never had it. I suspect it might be pretty easy... at least compared to my current projects!

Aftermarket heated screenwasher systems have been around for quite awhile. I remember reading ads for the Hot Squirt brand system 22 years ago in the back of car and mechanics magazines. Me, I've always been sort of cautiously avoidant of this idea, for fear of cracking the windscreen. It doesn't take much to do this; on one bitterly cold Michigan morning a few years ago, I started up my '92 AA-body Mopar, turned on the defogger and drove off. About two miles down the road, a crack ripped across the entire screen, right to left, immediately above the defogger vents. Made a hell of a noise when it let go. And the defogger air was not very warm at that point!

That said, I did experiment with a crude homemade system on a '91 ex-police Caprice I owned (not briefly enough to prevent having to buy a transmission!). I spliced in some extra screenwasher hose between the reservoir and the wye fitting, and wrapped a couple turns of it around the upper radiator hose. No overtape or any other insulation.

It didn't work. When the engine was cold, there was no difference. When the engine was hot, it overheated the fluid, which sputtered out of the screenwasher nozzles as a more-or-less 50/50 mix of liquid and vapour. I reversed the modification rather than futz with different fluid formulations.

In any event, Here's a thread on the topic with a bunch of suggestions for sources and homemaking.

If you want high-dollar, go get a Webasto BlueHeat for four-figure money. (Maybe not. Here's their screenwasher heater.

Final comment: I was initially sceptical, but Rain-X screenwasher fluid is an immense improvement over the regular blue stuff.
Cracked windshield? Whoa. Thanks for the warning, Dan.

I've been thinking that the best way to do this would be to use electric heating. Water heating seems less useful - by the time it reaches operating temperature, I'd already have a working defroster.

And thanks to your warning, I'll be sure to add a shutoff before it gets too hot.
Just want to add - my '91 Mercedes 300E has a stainless heating coil in the reservoir, using coolant to heat the w/w fluid. While this works well on ice, and fabulously well to remove bugs from the windshield in the summer, it has two problems. One, it boils the alcohol out of the solution, causing it to freeze. Two, the hot concentrated detergent that gets the bugs off so well, also removes the wax from the car wherever it splashes! So it would be nice if it were thermostatically controlled, but it is not.
I lived in Buffalo from 1963 to 1971 and Rochester NY from 1977 to 1998. 85 ave inches of snow spread from thanksgiving to Apl each year. Despising the labor of ice scraping led me to slowly pour a gallon of hot tap water over the ice each morning to get rid of it (I would guess 110F). Never cracked a windshield. The cars used were 66NYr, 69Electra225, 66Valient, 65mercedes, & MGA.
A lot probably depends on the individual piece of glass and its mounting rubber.
Dude, the freezing point totally tells you at what point the fluid will freeze. You're in Georgia, so your experience is with how quickly it removes the ice you get -- the lower temp stuff has more alcohol, so of course it works more quickly for what you're using it for. But for those of us who live up north -- Minnesota, North Dakota, Wisconsin -- those numbers DO tell us which blend will not freeze solid in our cars' reservoirs while parked overnight, or driving down the road. Seriously. Truth.
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