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Knocking sound troubleshooting

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Just got back from an epic two weeks camping and wakeboarding trip , everything ran perfect untill i came home , brought the boat round the dock unpacked and then started her up again to hear a knocking sound in neutral coming from what i would call the back starboard side of the block cylinder 7 (i think) .. she just ticked over 700 hours on the way back from the trip

what could it be .. valves need adjusting , new rings ? hope to hell it aint the big end bearing ... although i would guess it would be making more noise if that was so ..

any simple tests i can do to check ?

any advice would be greatly appreciated

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Check the oil for color (chocolate milkshake is not what you want to see), check the exhaust manifold bolts and gasket (look for any soot around the port) as that can make a popping sound, pop off the valve cover and check the rockers for looseness & pushrods for straightness. Did it take on any water at any time? The damper plante can also make a knocking sound. 700 hours is no big deal.

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nah no water i don't believe , the valve cover is my first port of call tomorrow morning along with the plugs and oil . but i didnt think of the exhaust manifold , will be sure to add that to the list...

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will the damper plate still "knock" even in neutral ? i did notice a slight grinding (more than usual ) when just about to change into drive. And the boat seems to want to spin the prop at higher revs even in neutral , but only ever so slightly.

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