I am interested in the answer also. I have 1976
westerbeke 30B. I have not located an overflow bottle. I think my
heat exchanger is losing a little water. The temperature guage is not registering which makes me think that there is not water in the block. There is water pumped out of the
exhaust but I think there is also steam. The
oil is not milky. I haven't had the time to investigate any further.
John