Just been looking on the thread I started on this about a month ago, and DervBoy's method of doing it seemed to be the most straightforward way of doing it, and a combination of what a fair few other people had said. If you don't remember it, here's our Graham with a quick reminder:
What I do is as follows:
Drain as much of the coolant as possible then tighten drain plug (or bottom hose). Fill up until overflowing with fresh water. Run the engine for a minute or two (don't bother waiting for it to warm up fully). Drain again Insert hosepipe into top-hose stub on rad and flush until clear water emerges. Put everything back together. Fill half of the stated coolant capactiy with neat antifreeze, then top up to line with water. Start engine and top up with plain water if necessary. Drive until warmed up, then check level again. Top up with plain water if necessary.
The above procedure ensures that most of the old antifreeze is removed from the heater and radiator.
Basically, I've got one question - it says "drive until warmed up". Now "warmed up" means that the thermostat has opened and coolant is running through the radiator, correct?? Or does it mean you've got to wait until the fan cuts in? Thing is, due to the nature of diesels (is it to do with a lower combustion temp or something?), the fan rarely cuts in on mine unless in really really heavy traffic - I don't even think in general driving it even gets hot enough to open up the thermostat, though I could be wrong.
Is a good caning around the block in order (after a couple of minutes of giving the oil a chance to warm up first, that is) so as to get the temperature up???
Peter