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

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

A mechanic's stethoscope is great for this type of work. You can substitute a long metal rod, for instance a long screwdriver, as a stand-in. Put the tip against the water pump (prime suspect in my opinion) and push your ear against the other end, and the screwdriver will transmit the noise from that component to your ear. Move it around to other accessories and compare the noise volume.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

Do this ^^^ AND be very careful not to let the listening device be struck by anything rotating e.g., the fan. The noise fed back to the ear is painful...you probably have guessed how I learned this.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Well, I will use the long screwdriver tip to try to isolate the noise. Funny thing is the car is not leaking/ losing coolant, overheating, etc....just chirps until warmed up, then the noise is gone.

Take a bar of hand soap and rub some on the v portion of the belts. Could be a belt chirp.

Crap......never thought of that.....could be something that simple.

Best way to start is to remove the belts. That will tell you whether it's an ancillary or the engine. Then replace the belts one at a time. You won't have to do this for more than a minute or two, so there's no worry that the car will overheat.

Probably not the problem but so cheap and easy to eliminate it. As a possibility.