Metallic chirping

[psaboic]

Hi folks,

Over the last two weeks the 1983 300D has developed a kind of metallic chirp/rattle sound at idle. Almost sounds like bad ball bearings, but not quite. Doesn't matter if it is hot or cold, and it doesn't seem to do it (or you can't hear it) above idle. Anyway, as best as I can, I've narrowed it down to where it seems to be coming from either the fan, the fan clutch, or the water pump.

Questions:
1. What is a good way to isolate/confirm where it may be coming from.? I really don't want to take off the belts if I do not have to as that is kind of a PITA, but if need be I can.

2. Any good tests for the fan clutch or water pump? The pump does not appear to be leaking, but I know that doesn't mean the bearings are not shot.

3. How hard is it to to replace the flan clutch or water pump? And write ups available to follow?

Many thanks in advanee.

Glenn