500SL Auxiliary fans

[Momo]

(I have read all other notes in this forum that refer to the auxiliary fans.)

It's been hot here in the Alps. 35 degrees C/ 95 F. Blasting up the mountains has been great fun. However, yesterday, after a fast blast, with the motor stopped, about a pint of coolant water dripped down under the car. The temperature gauge was just above mid-level at about 105 C/220F. I could hear the water bubbling (boiling?) in the radiator area, and the expansion chamber was completely full. While I am not absolutely certain, I believe the water came entirely out of the expansion overflow. Not had this before.

After topping up, I continued with another fast run. With the temparature guage at the same level, I stopped and looked under the car with the engine running. Bone dry. However, I noted that neither auxiliary fan was running. (The a/c was off) Once I stopped the car, I had another very small overflow. It's a bit cooler today, and I can't get the temperature up that high again, even with the a/c running. All other liquids are at their normal levels. All fuses OK.

My general question is "What should I look at first?". Specifically, I would like to unerstand in what circumstances the auxiliary fans are supposed to work. Should they, for example, like in some cars, continue to work after the engine is stopped?

Suggestions?

Momo