The M102 engine has an electro magnectic fan. This fan free wheels just like a clutch fan but engages electrically from a thermo switch on top of the engine block. It is often mistaken for a viscous clutch system except it does not gradually get stiffer it just cuts in (100 C)and then cuts out.
88 230E (W124) M102
[This message has been edited by yal (edited 07-26-2000).]