Hello, '89 OMC 3.0 130 is knocking after 2 hrs of driving. I think it is coming middle of the engine, around crankshaft or camshaft. Removing spark plug lead one by one, there is no difference in sound. Cold engine runs very smooth without any noises, but when idling about 1 minute after cold start, knocking starts. Here is a link for video and sound: https://youtu.be/xw4xiDKlM70
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