It is a mid 80's , 40 hp Yamaha. I found oil in the lower unit last year. So I took it off and brought it to the shop. Well they decided to pull the water pump assy. As it is nearly 15 years old I thought for sure it would be the problem. But it looked perfect. The mechanice put on a pressure gage and it held 25 psi for 15 mins. He said there wasn't a leak as new ones hold 18 psi. Any ideas what might be the problem?
