Hi Aussie,
Sorry to have been a bit blunt in my last post. Whoever put that electric pump on the Saracen was not curing a problem. There is a possibility that the engine's water pump has had the impellor split (they are pressed on) and the parts could be obstructing the ports in the pump. The water flow in these engines is not like common engines, there are differences. Once the front armour is off, the rad can be removed leaving the fan assembly, and it will be a good exercise to make sure the fan belt adjusting pulleys are free to move, the sheaves are threaded.
regards, Richard