The radiator will clog worst in front of the fan since that is where the most cooling takes place.

Do a citric acid flush to see if that helps (although it won't always clear a corroded radiator). If you still run warm, get a new rad, it's a bit cheaper than the new head you will need if it overheats....

If the fan clutch has sticky dirty oil all over it, it's bad -- but a bad fan clutch won't cause trouble on the highway, only in slow traffic. On the highway, running too warm is usually a bad radiator.

Peter

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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!