Sounds more like a rad clogged up or a pressurization problem, but the fan clutch is easy to replace.
It's not so easy to buy, though -- I think I paid $175 for mine!
One 8mm hex socket bolt in front, you need something to stick in the slot on the pulley bracket to hold the clutch so you can unscrew the bolt after unclipping the shroud. Three 5 or 6 mm (I think, don't remember) hex bolts holding the fan to the clutch.
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!