I bought a new clutch for my '87, it was for the metal fan.

detach the shroud, push it toward the engine, and you should be able to get to the allen bolt. With the belt still on, you might (I have twice) have enough drag while pushing on the belt, to hold the pully for loosening the bolt.

A plastic fan doesn't have any significant change in engine load, it's in how efficient the blades are and how much air it moves, not the small change in weight. Since the fan doesn't engage suddenly like an electric clutch, the inertia is also not significant. I did polish the blades on mine while out of the car to reduce airflow resistance, and then coat with teflon, so mine is probably more efficient than the as-molded plastic blade. Plus it's cool. I didn't look at the fan closely, but it seems light enough to have some mag in it. Should have a stamp on it with the alloy (for recyclability), Mercedes required it on all of the parts we made for them.

__________________

Gone to the dark side

- Jeff