The 300E has a funky double cross flow rad -- both hoses are on the same side, "bottom" hose is half way up. Coolant goes into the top, across, down the side, and back across the bottom half in the opposite direction.
Yes, if you have very hard water (and Miami does, it runs from Tallahasse all the way down the state over limestone) and use green coolant, you can make rock in the rad! Will plug in no time, that's why I recommend MB coolant (no phosphates) and distilled water.
The real diffuculty here is both the precipitation of calcium phosphate in the rad along with the serious corrosion problems phosphates will cause with aluminum. I'd rather replace the rad than the head.....
Cloggin of the rad can be checked with the infared thermometer -- there will be cold spots in front of the engine fan, where the most crud is.
Speaking of which, do you have residual pressure in the cooling system cold Mike? If so, you may nave other problems.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!