Originally Posted by gsxr

Be careful messing with the 1987 300TD cooling system. Those heads do NOT tolerate overheating one bit; <-- fact #1

There's not room for dual 12" fans on the W124, the radiator isn't wide enough. A single 12" isn't adequate, IMO. Try to find a single 16". The depth is quite limited as well. <-- fact #2

Your test points out what I keep trying to tell others, that the fan really DOES do something on the freeway... everyone seems to think the ram-air effect is plenty but it is not. <-- fact #3

The alternator upgrade is cheap and easy - I would NOT skip this step!!! The stock alternator can't even keep up with the basic electrical loads at idle (lights, ACC fan, etc...) <-- fact #4