V8 cooling fan circuit

black olive · 14th August 2009, 22:19

have a look here- this connector is also accessible with the front off

http://www.the75andztclub.co.uk/foru...ad.php?t=42738

SD1too · 15th August 2009, 08:30

That's interesting Steve. I've looked at MG Rover's circuit for the V8 and it shows the same arrangement as my KV6 which is all the relay coils supplied with 12v when the ignition is 'on' (the yellow wire). Each relay is then triggered by earthing the appropriate relay coil (the blue wires). Now it wouldn't be the first time that the MG Rover information has been found to be wrong! For example they are still showing that the 'fast' speed is achieved by supplying a third brush with 12v, but we know that this brush is, in fact, earthed. So my question is: are you 100% certain that the circuit has indeed been "turned on it's head" for the V8?

It's also interesting that the low fan speed has been disabled on the V8. I think we need to know more before venturing a reason for this. For example, does the V8's ECM fan strategy differ from the other cars? There's some doubt in my mind that the change is to reduce brush wear. On my 3 speed fan it was the earth brush which had worn down to nothing, the others were serviceable. If the V8's fan strategy is the same as my KV6, then removing the low speed would actually increase the wear on the earth brush (due to the higher current passing on medium speed).

Simon.

14th August 2009, 22:19	#1
black olive I really should get out more....... 260 SE vin 214 ( last mark 1 260 ) Join Date: Dec 2006 Location: Lancashire Posts: 2,009 Thanks: 1 Thanked 8 Times in 4 Posts	V8 cooling fan circuit have a look here- this connector is also accessible with the front off http://www.the75andztclub.co.uk/foru...ad.php?t=42738 __________________ [SIGPIC][/SIGPIC]

15th August 2009, 08:30	#2
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,640 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	V8 cooling fan circuit That's interesting Steve. I've looked at MG Rover's circuit for the V8 and it shows the same arrangement as my KV6 which is all the relay coils supplied with 12v when the ignition is 'on' (the yellow wire). Each relay is then triggered by earthing the appropriate relay coil (the blue wires). Now it wouldn't be the first time that the MG Rover information has been found to be wrong! For example they are still showing that the 'fast' speed is achieved by supplying a third brush with 12v, but we know that this brush is, in fact, earthed. So my question is: are you 100% certain that the circuit has indeed been "turned on it's head" for the V8? It's also interesting that the low fan speed has been disabled on the V8. I think we need to know more before venturing a reason for this. For example, does the V8's ECM fan strategy differ from the other cars? There's some doubt in my mind that the change is to reduce brush wear. On my 3 speed fan it was the earth brush which had worn down to nothing, the others were serviceable. If the V8's fan strategy is the same as my KV6, then removing the low speed would actually increase the wear on the earth brush (due to the higher current passing on medium speed). Simon. __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.