After years of dealing with a jet aircraft landing roar which turned heads and frightened newspaper vendors at the traffic lights, I was forced to address it when a rather expensive sound was rattling at the front of the 3.2 Di - D motor.
The viscous was ALWAYS on, even if it was 17 degrees outside and not driving hard. FLIPPEN noisy.
Guessed the new noise was v- belts, as it calmed down as motor warmed up.
Decided to pull radiator and clean a few years of trees out.

Did belts, never been changed.
Checked pulleys for play ..found that the main crank pulley was a bit off centre. But looked ok.
Sorted a few rattles from the air box.
Had radiator cleaned at Silverton PE and tested thermostat to see if this was the culprit for running viscous all the time.
My test showed it opens at 87 deg instead of stamped 75 deg
Silverton confirmed the high opening temp...
This was at no charge, thanks guys.
Dealers reported no stock of thermostat in the country......... Found one at Auto Zone, more expensive than the out of stock original!( thanks Imperial)
Fresh antifreeze.
After starting, noticed noise was still there, but now there was a metal to metal sound. Saw the main pulley was running really bad now.
Stripped all out again and found that the front pulley had separated. It's a two part assembly, presumably for vibration damping.
Panic sets in. Call to the dealers reveals one IN STOCK , in PE !! R2200

After a call to Marius 4e Pikanini (?) on the bolt removal trick ( Thanks boet), new pulley fitted, reassembled all.
All quiet now, including only occasional running of the fan which quiet end down in seconds.
So motor has been running 10 deg hotter for more than 2 years!
Plus I'm sure there was a fuel consumption penalty for running that fan all the time..
Only issue now is that I can hear the motor clearly now, and a few other rattles!
Alan
2010 Pajero Sport
Yes , it IS a sport again......