Modified 90 Degree Auxiliary Fan Sensor

I recently saw a modified auxiliary fan sensor that was activated at 90 degrees, rather than the usual 100. Seems like a good idea, though I imagine one pays for lower engine temps with more aux fan wear.
Still, the tradeoff seems well worth it.
Has anybody used one of these? Or is there any other downside to using one of these devices that I haven't considered?
Thanks in advance
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Engine temp will be cooler but it will not be below the operating temperature. The only sensor I know that runs at 100 or 105 degree is the backup temp sensor in case the primary sensor for aux fan failed or the engine fan clutch is failing.
So it seems like a good idea, it was telling you that you have problem in the first place. So fix this problem first.
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wrote:

Thanks for the response, Tiger, but I'm not really sure what you mean. The people that have been using this claimed that the engine temp was 5-10 degrees lower when they used the modified sensor, which seems reasonable if the aux fan came on at a lower temp?

Correct me if I'm wrong, but I was under the impression that the temp sensor on the thermostat activated the aux fan circuit at 100 degrees on my 81 380sl and other 107's?
Here's a variation of the them, called the Cool Harness, for other models.
http://pages.prodigy.net/jforgione/MB_S500.html

Actually, my aux fan went kaput, but I was thinking of trying a modified, too.
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What I meant is that the thermostat will ultimately dictate the lowest operating temperature... if the thermostat is rated at 85 degree... that will be the lowest temperature you can achieve before themostat will start closing to increase temperature.

I had 380SE so there is no difference in engine. There is one or two sensors... single pole connection with red coloring on it... these control the aux fan. There is one I think double or triple prongs... this is for AC aux fan trigger and overheating protection to turn fan on at 100 degree.
These sensors have date of manufacture stamped on the wrench hex side... if it is more than 7 years old... change them all.
The black single prong on the thermostat housing is for engine temp display... this rarely go bad.
Our temp gauge in the instrument cluster do go bad... showing increased operating temp when in reality... it is not. I would use infrared thermometer at the thermostat housing to check the accuracy of the temp gauge.

Other thing you can do to lower temp is keep your radiator clean... blow with air or wash with water... from inside the engine compartment toward the front of car to backflush any bugs or dirt stuck in radiator cooling fins.
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Agree. The thermostat determines the engine temp. The fan mainly cools the radiator at lower vehicle speed. Unless the car is in stop-and-go traffic much of the time, activating the fan at lower temp really does not make much difference.
On the other side, the engine is designed to be operating at certain temp. Lower it may not keep the best performance/efficiency or even the emission.
Tiger wrote:

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Wan-ning Tan wrote:

One would also think by now if there was an advantage to the lower temp, the manufacturers would have done it a long time ago. After all, the cost of a 90 or 100 deg switch is the same.
Still, I wonder if it would make any noticeable difference in the A/C which has a switch to turn the fan on if the AC condenser gets hot enough. That fan seems to only go on at a relatively high temp of like 100 too.
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