Mercruiser 3.0 noise/knocking

[ipman]

Hi

I have a 1998 3.0 LX that has 10h hours on the meter since rebuild last winter. Only 10h put on it last summer before putting it away for the winter.
Had a problem with the ignition at first this spring, it wouldn't advance it so engine ran lika a hog. Replaced ignition module (Delco EST) and everything was fine again.
First run out this year it only took a couple of miles when this knocking sound started (see video). It's really hard and sharp, sounds like a rod is coming out the block. It follows the rpm but the funny thing it comes and go within half a minute or so?! Sound is there without load on engine, video is taken at dock...

I've got 170 PSI across all cylinders, all valvetrains are firm and equal (no lifter breakdown or stud pullout) The engine runs really fine so I'm fearing this is a bearing issue, but never heard one come and go, back and forth.

Any input on this problem, anybody recognize the symptons?

Regards
/Petter

 

[pro-crastinator]

Harbor freight tools sells a mechanics stethescope that would be real handy locating the specific location of the noise.
few bucks.

good luck. that knock sounds scary.

 

[Stingray190LS]

ipman... were you able to figure out what the issue was and where that noise is originating from? I'm afraid I have the same scenario and could use your insight. Thanks!