1986 740 GLE non-turbo B230F 204k miles with possible coolant leak. Have had to add 1/2 quart of coolant to overflow tank twice in past week with 100 miles or so of driving. Cannot see leak on outside surface of water pump (can't see weep holes). No leaks around radiator, hoses, or engine block seen. No white smoke from tail pipe. Pressure testing coolant revealed no loss of pressure at 1 minute and 10 psi.