I am wanting to put an electric fan on my 420 and was told that I would have to modify or replace the pump thermostat to close bypass flow. Can someone clarify this for me, and what exactly would I have to do/buy in order to accomplish this? Also, the fan will be either a 2000 or 2500 CFM unit, activated at 100C, does this sound correct?

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'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.

"A Mercedes-Benz is like a fine wine, it only gets better with age."