Originally Posted by Jeremy5848

Thanks, Sixto, I'll revise my list.

Comment: The OE switch in the 1987 300D/TD does not turn off the a/c compressor until the coolant gets to 128°C. In my opinion and Sixto's, this is waiting much too long and may be one reason why this engine is known to crack its head. Replacement of this switch with one of the others, mechanically and electrically identical except for the temperature settings, is advised. About $30-40 new from your dealer or $5 from a wrecking yard.

Mercedes-Benz auxiliary fan (high speed) and compressor cut-out switch part numbers are:
• 006 545 64 24 (used in OM603 of '87 300D/TD only) 105ºC/128ºC with blue top
• 006 545 42 24 (used in M102 and OM601 engines plus OM603 of '86/'87 300SDL) 105ºC/120ºC with gray top
• 006 545 45 24 (used in some M103s) 105ºC/115ºC with green top
• 006 545 61 24 (used in M102-3-4 and OM602 engines) 100ºC/110ºC with red top

Don't forget to install a new crush washer if you change switches.

Jeremy