When is the second fan supposed to start?
 

My 260E heated up to 100C and the second fan did not start yet. When is it supposed to kick in? I admit that I had the car at about 90 MPH for about 15 minutes and when I stopped at the intersection the temperature went up and then stopped at 100. After I started driving again it was at about 90 and it stayed that way until home.

Thanks, Igor.

It would come on high speed at 105deg on 86 and 87 models.

The 260E has an M103 motor as does my 126 car. One of the differences is engine bore. The 260E is 2.6 litre; the 126 300SEL is 3.0 litre - both in the M103 family. In my case, the high speed aux. fans kick on at 102 degress centigrade.

My temperature never reached 105C but it made me very nervous reaching 100. I am used to it on my 1985 300TD but not on this car. The temperature just fluctuated like crazy today, on the open road it would drop to about 82-85 but as soon as I stopped at the traffic light it would climb back up to 100. I also must mention that the front fender on the passenger side of the car (next to coolant overflow jug) was extremely hot. I mean, to the point where I could barely touch it. The car sometimes smells like coolant very strong but it doesn't leak anywhere.

Any more help is greatly appreciated!!

Igor

The temperatures you mentioned are normal. You will find a lot of information on this in the archives.

Above 20mph, the cooing sytem does not need any additonal air flow from the fans.
Below 20mph is where the main and aux fans come into play.

It is possible that MB temperature gages are very sensitive and accurate while other automakers make the gages less sensitive to avoid unnecessary concumer concerns.