I think that your car has the newer type viscous fan clutch. If that's the case, it will WILL NOT ROAR when it engages. The best way to test it is as follows:

Next time your engine temperature rises above 100C, do the following:

a) With the engine idling, look closely at the rotating fan.
b) While you are looking at the Fan, get a helper to shut-off the engine.

If the fan stops turning within 1-2 revolutions than its OK. If it free spins for a long time than it needs to be replaced.

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]