Marine Power 350K Loud Knocking

Just getting ready to put boat in. Engines started and ran fine last week. This week after running at idle for a period of time i noticed a knocking in engine that got louder and faster as rpm's increased. MY mechanice says he has to pull the engine to know what it is buts its most likely a cam and shaft or piston.

COuld this be related to old gas. The gas thats in there is going on 2 years old..I used star tron and the enignes seemed to start fine..Is there anything else this can be? I hate to think we pull engine for nothing

Knocks are typically rod bearings; causes can vary.

I doubt it has anything to do with the gas unless it flooded out frequently. Even if that happened, it wouldn't be due to the age of the fuel.

yes old gas will knock!

Before pulling the engines out, try a fresh oil change with a quart of Rislone or Marvel Mystery Oil added. It may be a sticky lifter, which will free up after running a few hours with the oil additive. When it stops making funny noises, change the oil again. If it continues, well then the engine will have to come out of course. Certainly worth trying the 5 buck fix before getting drastic.

Just had this happen with my Range Rover, and the Marvel Mystery oil cleared up the noisy tappet after about 100 odd miles.

Personally I'd run it until it fails, there is another engine to get you home. Besides, if it is a bearing you have to take it all apart anyway so might as well use it right up to the point that it actually HAS to come apart.