Thanks Guys. The engine was removed from the boat twenty years ago to 'have some work done on it' by the original owner, who passed away suddenly before completing whatever it was he was doing. It was still hanging from the floor joists under the house in the chap's home workshop on a block and tackle when I collected it. I bought the engine from deceased owners' son, he remembers being on the boat this engine was fitted to many times-and had never been under water.
The owners home is about 75 metres from the ocean here in New South Wales south coast, and salt laden air over two decades has taken its toll :-(
I'll take it apart and see what's inside. I doubt I can do any more harm! Cheers Will.