It was 102 degrees here in Dallas yesterday as I was driving home in my '84 300D Euro. I watched with mounting chagrin as my thermo needle climbed above 100 C. I hoped it would stay there, but after only a momentary pause, it began making its way up past 110, then on to the dreaded 120 red line. It was about at this point that I needed to use my brakes to maneuver the Arlington/Dallas rush hour traffic. But it's difficult to use brakes when your brake fluid is boiling from the intense heat in the engine compartment. It was the previous day that I drained my radiator (save for about 15% antifreeze/water solution), and added Red Line Water Wetter. I'm convinced this stuff is really just strawberry-flavored Kool-Aid.

Actually, the point of all this is a question: should my aux fan have been running, or does it run only when the A/C is on(which it wasn't)? After my poor Benz cooled off, I drove it around to warm it up and see if the aux fan would kick in. It never did, until I cranked on the A/C. Is this normal? I know that 120 degrees centigrade is NOT normal! AAARRGGGHH!!!

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Matt
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'84 300D Euro

Do I assume, when you described that you were driving home, that you were driving along at a reasonable speed?
Your auxiliary electric fan is only important when you're crawling or stationary in rush hour traffic. If you were driving at normal road speed, say 30+ mph, and you were overheating, that little electric fan (or even your viscous clutch main fan) are definitely NOT the culprit. The normal "ram air" of the car's velocity overwhelms any contributions of the fans. You have to look elsewhere for the cause of your overheating.

Matt,

I can't answer about the aux fan, but would hazard a guess that it probably should engage after a certain temperature. You can probably do a search for this topic (search is near the top on the right of the display, in small print.) Is it possible that the thermostat in your 300D is not working properly? Just a thought…

I'll add that I put water wetter in one of my cars about a week ago and have been delighted with the results. In the past in 80o or warmer weather I couldn't use the AC in this car unless it was on the freeway, due to the combination of outside temp and in-town traffic would make the engine temp soar; with water wetter it behaved favorably and I've been enjoying using the AC. The temp gauge reads about 10% lower all things being equal than prior to putting in this marvelous product

...tracy

Thanks for your replies, Tracy and Ken. I was no doubt a little hasty in condemning Water Wetter as the culprit. I was merely venting

There are a number of things for me to check now, at your suggestions, and others'.

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Matt
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'84 300D Euro

The aux. fan is triggered buy a temp switch on the air dryer and it only has power when the A/C is on. I did a little experimenting with this fan and it has little or no cooling affect on the rad, it is ment to cool the condenser.

You said you drained your cooling system the other day. You sure there aren't any air pockets? Might want to double check that.

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Rgds,
Aaron Greenberg
MB technician
Precision Motorcars, Cincinnati, Ohio
'67 250SE Cabriolet
'77 450SL
'80 300SD
'85 380SE
'86 420SEL
'89 420SEL
'93 300E 2.8
'74 Jensen Interceptor Mk.III
'81 DeLorean DMC12
'84 BMW 745i Turbo

Yes Aaron, I agree. For others thinking about adding Water Wetter, I just added mine to the overflow tank, figuring that eventually it will get sucked back into the radiator after enough heating and cooling cycles. My 84 300SD runs between 95 and 110 deg C with the air on or not. I had a new thermostat put in; before that it ran at 85 deg C then when it went bad it never got over 60 deg C. I got like 14.5 mpg on that tank of fuel (normally get closer to 20 mpg in town). Just my 2 cents.

I did the same thing as you Robert. I noticed a decrease in temp by 2-5 degrees. And mind you, I am in Phoneix, with AC on all the time, and afternoon temp is generally 105 to 108.

Another "thumbs up" here in Tucson for water wetter. Our temps pretty much duplicate Phoenix (maybe a tad cooler..). With WW in my 89 290E 2.6 the temps were down almost 10 degrees! Although I've recently had a new water pump/thermostat-condensor installed.

Dave Browning
89 190E 2.6

Water Wetter is very effective..take it from me; my 500E has NEVER been north of 105, and rarely sees 100 degrees. My 300TE runs no hotter than 90 EVER. Great product.

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Best regards, Michael
'92 500E
'88 300TE