Ugh, after replacing the temp sensor the other day I had a massive overheating problem today (after driving really slowly round a car park for ages ) - had steam shooting from the top of the rad cap, which I waited till had cooled etc then topped up with plain water trying to get home, then 10 mins later had steam coming out from the engine around the spark plug area - got the AA out and although there was water/coolant in the expansion tank, there was none flowing through the system and so rad was not getting hot - took apart to check thermostat which physically looked fine, so AA mechanic reckons it's probably a water pump.

I've got the procedure for taking out water pump in my Bentley and in Haynes, and hopefully the impeler is going to be noticeably broken so I can buy a new pump. Anyone any pointers/ gotchas on the replacement ? I see I need a 32mm spanner which I don't have - hopefully my adjustable one wont be too fat to get in the space!

Cheers