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Old 08-27-2002, 07:59 PM
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Join Date: Jul 2002
Location: redmond washingtom
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170 degree washer fluid?

I have a 1990 300-E and today i noticed how hot the washer fluid was, is 170 degrees normal?
what controls the way that washer fluid temp is regulated?
i saw the heating coil out of the reservoir and noticed a black plastic part attached down near the bottom, what was it?

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Old 08-27-2002, 08:47 PM
Join Date: Jul 2001
Location: Old Lyme, Connecticut
Posts: 3,596

Engine coolant is circulated through the coils to keep the stuff hot and effective in freezing weather. 170F seems a little hot though, like it could hurt if you got hit with a spritz.

I seem to recall spilling hot coffee while driving cost McDonalds some bucks, so the idea you could try cleaning the windshield off while stopped in traffic and spatter some on a pedestrian and end up in court is a little troubling. Kind of hard to hit the same spot as the McDonald's hot coffee got, but in an eye might generate some jury sympathy.

If you find out more, please post it, as water that hot seems potentially dangerous. Jim
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)
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Old 08-27-2002, 08:55 PM
Posts: n/a
Ther is no switch, valve or thermostat to control windshiel fluid temperature.
water circulates in the coil at approx 90degC, so the windshild fluid is very close to that temp..
it is a so-so good feature as in the winter, the high temperature boils away the alcool contained in the water solution, making it very easy to freeze during the night.
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Old 08-28-2002, 10:36 AM
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The result of another slow day at MB Engineering

Down here in the South this "feature" is about as useless as tits on a boar hog. I'm either going to plug mine together and let it recirculate without going through the resevoir or add a small radiator to assist in engine cooling. The only thing it does on mine is cause the fluid to evaporate.:p
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Old 08-28-2002, 04:46 PM
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I thought coolant only circulated through it when the heater was on. I'll have to check mine.

BTW, it comes in handy in places like Minnesota and there were times when I lived in North Carolina when it was useful as well.
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Old 08-28-2002, 05:15 PM
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You know... it is an absolutely wonderful feature... however, one time when I was using the windshield washer while driving 80mph or so on Hwy 395 near Mammoth Lakes, CA, the ext temp was 28d F. As soon as I activated the washer fluid... the fluid would end up freezing on the windshield!
Does this happen to anyone?
2006 E350 w/ 155k miles (Daily Driver)

1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
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Old 08-28-2002, 05:49 PM
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Location: Knoxville, TN
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If you use the blue stuff that you can get at wal-mart or pep-boys that freezes at -20F, you won't have a problem. I have used it in sub freezing temps without any freezing.
Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
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Old 08-28-2002, 07:00 PM
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If you use washer fluid with anti-freeze, (alcohol) then you don't need to heat it for it to work.
David; the reason it freezes is that hot water freezes more quickly than cold because once it starts giving up calories, it does so at a faster rate. So actually MB shot themselves(us) in the foot with this gimmick.
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Old 08-28-2002, 07:07 PM
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Join Date: Jan 2002
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I live in So. Cal and I run straight distilled water in my windshield wiper fluid to maximize heat absorption. The hot fluid can actually dissolve any crap that is stuck on your windows. I remember one time I turned it on and it was like a jet of hot steam at my window but almost immediately, my window was crystal and I mean crystal clean. I was driving to Las Vegas, so I bet the engine was getting relly warm. Run straight distilled and you wont have any water spots.
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Old 08-28-2002, 07:49 PM
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If it has heat and pressure, it will leak!

One day, when that fragile pipe corrodes and engine anti-freeze combines with washer fluid, two things will happen. Your motor will run hot and if you rinse the windshield, you won't be able to see a darn thing.
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Old 08-28-2002, 09:21 PM
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Location: St. Albert, Alberta, Canada
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Word from the Frozen (and I mean FROZEN) North...

Maybe our winter washer fluids are made differently, but this feature works GREAT in Canada. On occasion when I drive our Mazda 626, I am reminded of how superb the MB engineering does work.

The washer jets are heated, and the washer fluid is heated. It means the nozzles are always clear, and the fluid never freezes when hitting the cold windscreen.

I LOVE it!

(Heated mirrors, heated washer fluid, heated nozzles and heated seats? Germany gets winter, unlike parts of Texas!)
John Shellenberg
1998 C230 "Black Betty" 240K
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Old 08-28-2002, 09:43 PM
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Location: redmond washingtom
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So from what you guys have said so far the washer reservoir fluid temp is going to be controlled buy the engine coolant temp with out any moderation at all. That seems goofy to me.
Does anyone know what the black plastic piece that is attached to the bottom of the washer fluid heater is or does?

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Old 08-28-2002, 10:06 PM
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Location: Evansville WI
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I've been reading this thread for awhile now, too lazy I guess to confirm what I thought was true. So, I broke out the 124 disc here at home, here is a quote from the disc:

"The heat exchanger (tubular spiral) in the washing fluid reservoir of the windscreen washer system is supplied with warm coolant from the bypass flow to the heating circuit. A thermovalve in the heat exchanger maintains a uniform temperature of the windscreen washer fluid of +20C to +30C."

So it should be more like 70 to 85 degrees F, not 170 degree.
The black item at the bottom of the heating element I believe is this thermovalve that is mentioned.

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Old 08-28-2002, 10:17 PM
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Location: redmond washingtom
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Thanks Gilly
That makes sense to me, so it sounds like it might be time to get a new heat exchanger or a new little black part if it is available separately. I didn't think Hans would stay out real late at Octoberfest and them come in with bad ideas.

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Old 08-28-2002, 10:35 PM
Posts: n/a
I have a '91 300E that spent about 10 years in Minnesota. I never had washer fluid freeze sitting in a garage with ambient temps of -30F so the theory that the device *boils* away the alcohol in the washer fluid apparently isn't true. I think that those of us who have driven in -70F wind chills can appreciate this feature that I consider another brilliant MB design.

Now that speed sensitive volume control on the Becker radio is another matter
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