I have a 1985 mercruiser 3.0L 140 hp engine. Serial #GM 2774531. At the end of last season, I heard a weird noise from the engine compartment. When I removed the engine cover, my oil dipstick shot up about 50 feet in the air and into the bay. My engine got real hot and smelled like it was burning oil. I covered the dipstick opening with a rag and chugged back to the dock at 3mph. I just recently began troubleshooting last years problem, first on my list was a compression test of all 4 cylinders. #1 was 150psi, #2 was 130psi, #3 was 0, yes 0, and #4 was 150psi. I added the teaspoon of oil to #3, gave it a few cranks, and did another test, and got another 0 psi on #3. I am praying it's not a hole in my piston or the rings are shot. The only other thing I can think of is a burnt valve, or worn guides. Any other suggestions or tests I can do to get a definitive answer before I get prices on a rebuild. Thanks for your help.
