The boat is a 1979 Sea Ray with twin 470's and MR outdrives. Was out about a month ago and thought I had overheated the port engine which has a 3" heat exchanger. Coolant was puking out the overflow tank. Thought the head gasket was blown. All the spark plugs came out dry, pressure checked the cooling system and it held 14 lbs for 20 minutes. A leak down showed 10-15% on all cylinders. So it seemed the head gasket was ok. Pulled the outdrive off and found a chunk missing from 2 vanes. Replaced the whole water pump assembly in both outdrives. Shoved a wire and blew out the hose from the bellhousing to the hose connection at the transom plate. The bellows, and coolant hose in the bellhousing is new last year. Removed the 3" heat exchanger and found the two chunks. I replaced the 3" with a 4" heat exchanger. Made an adapter to bolt to the bellhousing to run the engine on the garden hose with the outdrive off. Ran the engine with new coolant and 4" heat exchanger for 20 minutes at 2000 rpm and the coolant newer got above 150. Had plenty of water flow out the exhaust. The port engine has an external alternator and the water cooled regulator is gone, so that wont be an issue. The engines got new points and timing set last year. The engines start up good and accelerate good so I dont think it is a timing issue. Was running the boat yesterday and the port engine got up to 190 while the starboard was at 150 at a cruise speed of 2000 rpm. If I let the port engine idle it cools off but takes a long time. Not sure what part to look at next.
