So, recently on my 1998 E300 turbo diesel, I replaced a bunch of parts... and circumstances as they are, I searched for the least expensive parts I could find that fit my car. Aftermarket AC condenser and aftermarket ($16) fan clutch I think are at the center of this story. So I was dumbfounded after doing the work, it seemed that my thermostat had suddenly failed in the open position . How weird to have happened right then? So the car was running way too cool around 60C. It always ran at appropriate temp of right around 85C. I could really hammer it uphill a lot and the temp would settle out where it normally did. But dropped too far down when coming down the hill and not romping!! Anywho, long story short , I changed the thermostat, no change. While checking coolant , I revved the engine and noticed the fan clutch was pulling enough air thru the rad and condenser, that it was able to turn the aux fans! The new fan clutch Is noisier and seems to move more air until it settles down. Further inspection shows the original condenser doesn’t allow the airflow that the aftermarket condenser does, I ended up blocking the top third of the rad behind the condenser and it now runs at appropriate temp. So although the aftermarket parts fit well and work well, it changes the way the stock system worked and required a modification . Other parts that were replaced at same time were water pump and coolant with mb spec coolant, Water pump was because of a small weep, and I can’t imagine the mb coolant runs that much cooler than green stuff that was in there before. Old and new water pumps were identical and old was still working well minus the small weep.


Anywho, some info to be gleaned from a small journey I had with cooling systems and aftermarket parts.