Engine noise identification

[Sam Sparks]

I have a 38ft SeaRay with dual mercruiser gas engines. I was cruising along and one engine started making this noise. Can anyone tell me what is happening here?

Oct 9, 2026

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[Sam Sparks]

Here is the engine tag info
MerCruiser MIE 340 (a 454 cubic inch / 7.4L Big Block V8) with 340 Horsepower, serial number A610756

 

[makomark]

maybe a rocker arm is clacking...hard to tell from just a snipet of video..

 

[Bt Doctur]

I agree, rocker arm sounding , If motor performance is still good suspect a rocker arm loose,stud pulled etc. If performance is down suspect a stuck exaust valve,