I've got a '92 300SD. I've replaced the radiator (leaked), water pump (over 125K miles), temperature sender, and viscous damper. However, it still shows on the dash as running hot. I've checked it with a laser thermometer and it's running at 185. I've checked the connections from the sender to the gauge and they check out as zero resistance.
So my mechanic tells me that MB mechanics are known to put a resistor in the line to bring the reading down to where it ought to be. I've heard of this before but wonder what the resistance ought to be. Or would this be an inadvisable fix?