1997 Crestliner Sportfish Volvo 4.3SX gas/freshwater. I have water entering the crankcase and mixing with oil; enough to fill the crankcase to the top of the rocker covers. Found the raw water pump impeller to be damaged and replaced it. Drained crankcase and refilled with fresh oil. Ran with cuff/hose at idle until nearly warm. Crankcase again filled with oil/water. Checked raw pump-OK. There is no oil cooler. Removed exhaust manifolds/exchangers to inspect. Not sure how to test. Had boat from new. Low hours(under 75). Stored heated indoors in winter(US Great Lakes area). Not sure where to go from here. Boat runs well(not smoking or missing);there was water in two cylinders(one each bank) when spark plugs were pulled from first filling.