Q. I have a 1996 750iL, and the water pump is dripping away. I don’t use the car much but I don’t fancy the letting the pump go. I don’t fancy paying the £650 I’ve been quoted to replace it either. Is this a massive job?

Trevor Henley, email

A. Well, they certainly aren’t easy! At least on the E38 the bonnet opens from the front which makes working on the front of the engine somewhat easier. I would take the radiator out first of all because space is at a premium with these. The viscous fan also comes off with a 32mm spanner (a proper one, not one of those pressed steel viscous spanners) and it’s a reverse thread, so clout the spanner clockwise with a steel hammer.
With the rad and fan out, the front crank damper pulley needs to come off because it goes over the lower securing bolt. On the V12, the water pump and thermostat housing are all one unit. Euro Car Parts do a Circoli pump for £90 and another one for £133 – both are way cheaper than the BMW one which is around £250.

Having the rad out is a good opportunity to give it a good clean up, and reverse flush it. Check the bottom for bowing outwards as well – it’s scrap if it’s not completely straight.
To refill the cooling system, leave the top rad hose off the radiator and refill slowly through the top hose, a litre at a time. The coolant capacity for a V12 is 15 litres so add six litres of anti-freeze first, then water. Leave the cap off the expansion tank for now, but as soon as the level is half-way, refit the cap and continue filling. As soon as coolant dribbles from the radiator top hose stub, the engine and radiator are full. Refit the hose, wash off all spilt coolant, fire up the V12 and hold it at 2,500 rpm until the heater starts to blow warm air. Recheck the levels and hoses for leaks.