On my 4.2 my viscous fan has recently started coming on at full power when the car is started is that normal? After 2kins or so it quietens down... Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

I've noticed this on mine recently & I'm thinking that it may be due to the drop in temperature, where it's taking a little longer to reach the desired system sensing, If you get my drift.

I’m guessing you have the jag engined 4.4? If so likely we have the same thing. Did it do it last winter though? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

I was under the impression that a viscous coupling on a fan engages when cold and gradually disengages as it reaches it's operating temperature.

If the temp goes above normal, then it engages again to cool itself and the associated radiator.

There's a viscous fluid inside that thickens and thins depending on temperature.

Mike

I was under the impression that a viscous coupling on a fan engages when cold and gradually disengages as it reaches it's operating temperature.

If the temp goes above normal, then it engages again to cool itself and the associated radiator.

There's a viscous fluid inside that thickens and thins thus drag, depending on temperature

Mike

Your're right 4.4 AJ engine. Difficult to remember, but not had any cooling issues.
I can remember hearing the fan cut in quite loudly back on a very hot day in the summer. Fan / engine quite after initial start up.

Mpirie, correct in what you saying. However these viscous fans operate as a normal fan, but also have a built in wiring loom / connection to cut in /out etc on the RR

Found this on Rave.

[img]http://www.fullfatrr.com/gallery/albums/userpics/17444/Fan.pdf[/img]

My TD6 (2003 L322 Vogue) seems to do the same occasionally - will have to make a mental note of ambient temperatures in future. 2003 Range Rover Vogue TD6

From memory the viscous fan if it has locked up ie engine was hot when you switch off it stays like that and doesn't reset until you restart - I may not be exactly correct but it is along those lines so I was told

Thanks sandy - so does yours sometimes do the roar when it starts as you have the same as me for 60 seconds or so?

Also when you turn the ignition on but don’t start do you get this noise form the supercharger pump up front?  Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Yes not every time but most and I changed the fan as well as all pulleys alternator zircon compressor water pump etc when it was 10 yrs old did it before and still does it

Thanks - do you get the buzzing sound in the video? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

There is no buzzing from mine (changed for a new one about a year ago).

There may be no coolant in it (check by removing the top pipe to it) or on its way out. You can access it quite nicely by removing the headlamp.

Great stuff thanks Stu

So with the ignition in position 2 and engine off no buzz like that?

Are you saying take the top hose off and there maybe no coolant if so i need a new one? Would I not see any symptoms of it failing or faults? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Correct no buzz. The problem may be the pump is trying to pump air - it's pretty easy to check, just pull the top hose off, if coolant comes out all good, otherwise you'll need to prime it and then bleed it (see the WSM - ignition switch to II and then the bleed screw on the expansion tank).

If the problem isn't air, and it's just getting noisy, keep an eye on it or replace it for a new one.