Yesterday gave me three simple jobs – stop the leak in the top hose, remove the viscous fan and finalise the wiring. Taking off the fan would be quick – I’ve done it before – so I started there 
The viscous hub on the fan attaches to the water pump shaft with a large 32mm nut, which is reverse-threaded (so that the normal rotation of the shaft causes the nut to tighten, rather than come loose). To undo it, one grips the fan pulley tightly, puts the spanner on the hub nut and moves the spanner in a clockwise motion – giving the spanner a “tap” with a hammer if it needs a little encouragement.
Nada … nothing … zip … zilch. Even after removing both the radiator and the fan from the viscous hub to get more room, it wasn’t shifting for love nor money. So, drained the coolant and took the water pump off. My vice doesn’t open wide enough to get the fan pulley in its jaws and the workmate didn’t give enough clamping, so another method of stopping the shaft turning was needed …
I got some bits of scrap, drilled holes in them and attached them to the pulley in a “Y” formation and put the tail of the “Y” into the vice. This meant the shaft couldn’t move (given that the pulley is bolted to it) allowing me enough leverage to undo the hub nut 
For clarity, here’s what the special “viscous hub nut removal assister” tool looks like 
I then cut a new gasket for the pump and put it back on the engine with a bit of Hylomar Blue for good measure.
On to the electrics – I pull the leads that were in there for first fix, worked out which ones needed trimming, stripped ’em back to solder the ends … then discovered that my new gas soldering iron from Maplins was dead 
Not empty, just no gas flow 
Dug out the receipt, got it swapped at the shop, re-did all the connectors, put it all back on the car, re-filled the coolant, turned the key and … click, click, click, click.
This is a new “not working” noise on me 
The battery’s on charge incase it’s just not enough oomph to turn the starter, but if it’s not that I’ll have to work my way through the book 
EDIT 17/02/08 :
micky-c : im no expert but the clicking noise sounds like the starter stuck try puting the car in gear then rock it back and forword a few times it should do the trick well it works on my tractor lol
Graham : classic flat battery noise, you turn the key and the starter solenoid engages the pinion and switches in the main windings, trouble is as soon as that happens theres now too much electrical load for the amount of juice in the battery so the solenoid disengages, now its disengaged theres enough power so it reengages, switches back in the main starter windings, guess wot, not enough juice again so it all disengages, and so the vicious circle carries on, until the nbattery is totally dead, or you get bored/help
as an AA patrol i see/hear this several 100 times a month!
me : Thanks for the most clear and concise explanation ever of what’s going on Makes sense now
Graham : quick battery test,
if its got less than 12.2 volts, it needs charging, if its got more than 12.2 you should have enough to start the engine, so see what to see what happens when you crank the engine, if the voltage drops below 9v on cranking the battery needs replacing
me : After charging for a few hours, the battery was showing 12.78V across the terminals, but I didn’t have an assistant handy today to check the reading when cranking, so I’ll try that at some later point. The battery’s beyond the end of its natural life anyway and is on the list of “things to do” on the short-term whiteboard Because it’s not in daily use though, it never seems to be enough of a problem to force me to change it – so I just charge it and coax a little more life out of it till the next time … and always have the defibrillator in the car whenever I go out 
Received wisdom appears to be to replace it with a 440CCA Transit diesel battery.
With the freshly charged battery, it turned over and fired first time, though – and then promptly spewed coolant out of both top and bottom rad connections when the thermostat opened The fan came on though, so for every ying there’s a yang…
It was at this point that I turned to my half-drunk mug of tea and realised it had ice forming in it – so thought it was some kind of sign I should come back inside 