re: efficient cooling ina vintage '87 300e
...if not done w/in the last 3 years:
will definitely need the dirt and muck removed & cleaned out between the rad and a/c condenser... must remove rad to get the crap out behind it= easy job
also check the cooling basics:
>adequate MB coolant (age/ mixture)
>proper working thermostat, rad, aux fan, viscous fan, water pump, aux water pump if so equipped, cap, belts/ tensioners/ hoses, expansion tank, system holds proper pressure. etc.
I have a proper cooling '92 than runs between 85-90 even in 105 degree stop and go dry ambient temps (a/c climi control activated)
hope this helps