My coolant pump started leaking badly I ordered a new one believe it or not they're still available for a 1974 I drain the coolant got about 2 and 1/2 gallons fitted the new pump everything seemed to be fine went to refill the system can't get any more than about 1 and 3/4 gallon into the system and it seems to be full I ran the engine watch the temperature gauge when it was finally seem to be full I'm not reading any more than about a hundred and forty degrees ran the engine for an hour no reduction in the amount of coolant in the system but I still have almost three-quarters of a gallon of coolant that came out of the engine what happened