Broken Down!

I made a casual check of the engine coolant level last night – and discovered to my shock that the header tank was empty. Which meant something like four pints of water had vanished. Then I checked the oil level, which had shot way up over its usual mark.
You didn't need to be Sherlock Holmes to deduce that the water had found its way into the oil!
This was a potential catastrophe: I feared a blown head gasket or worse and yet another engine rebuild, this time out on location in Birmingham. Not surprisingly I didn't sleep very well.
But at 5 a.m. I woke up thinking about another possibility. I recalled reading that leaking water pump oil seals can let the coolant leak into the engine. Maybe that was the cause? After all, until I checked the levels the engine had been running perfectly showing none of the smokiness or rough running of a head gasket failure.
By 8a.m I had the pump off - and discovered it was in a word knackered. The shaft was worn and badly scored so the seals weren't sealing anything. Perhaps the last burst of heavy load running when we tangled with the rope had been too much for what was left of it.
I siphoned out about four pints of virtually neat anti freeze mix from the sump then removed a side cover on the block and began the filthy and laborious task of spooning out the rest with a cut-down milk bottle. (Boat engines don't have sump plugs unfortunately!).
Out and out it came, a watery black mess that ran everywhere. Eventually I filled a ten litre canister and half a five litre one - the normal oil capacity being just over five litres!!
Remarkably once the mix had settled it proceeded to settle out into its constituent parts and we were able to separate off four litres of pretty pure looking coolant which I'm happy to re-use. The oil I think I'll be wise to ditch.
But the big problem was sorting the pump. Ours has been obsolete since 1973 (!) and there are no spares to be found anywhere. Believe me I tried. Its successor, which should fit with a few minor mods is also now obsolete but I finally found a 'new old stock' one for £150. Ouch.
It should be here tomorrow. Meanwhile we sit in the relative comfort of the Black Country Museum moorings and I keep my fingers crossed that a) it will fit and b) that it will cure the problem.