Hi - apologies for length of post<br /><br />I have a 3 cylinder Mariner 60hp 1988.<br /><br />I disconnected my alarm wire as it was faulty and remained on at all times, the tell tale stream is strong and at WOT the tell tale becomes very hot but still not too hot to touch, it quickly cools when running slower. I have had a new impeller fitted 2 months back.<br /><br />After running the engine at 2/3rds throttle the engine slowed and was only running on 2 cylinders. I discovered that the top cylinder was not firing. I removed the spark plug and noticed that there was a film of metal on the inside of the cylinder from where I had just removed the spark plug, I could not see into the cylinder. I prodded the film of metal and managed to remove some but some fell into the cylinder. I replaced the spark plug and it ran on all 3 cylinders for another 20 minutes then the same problem occured.<br /><br />The spark plugs were replaced recently, I replaced them with the same which were NGK BUHW.<br /><br />I have not compression tested as at present I dont have a compression tester.<br /><br />Any ideas much appreciated - thanks
