Steve,

Take a look at this post I recently made,
and let me know what you think. I like
your opinion since you are usually good
and verbose, and full of details. Anyways,
can you idle your boat (out of gear) with it
warmed up and take the cover off and stick
your head down on that non-manifold side
and see if you got this same clacking noise I
got? - 'preciate comparing notes. Thanks!

Here's what I recently posted:

So I finally got about 20 hours (I think) on my new 2005
Bayliner 175 Capri, and within the forst 10 hours, I
noticed a noise in the engine, and it seems pretty
pronounced at idle. It like a rattling noise, but the
best way to describe is that it sounds just like that
rattling sound of a diesel engine. I stuck my head
clean down in the engine compartment, and it seems
like its coming from the cover on the left side below
the head (where I think the lifters are at). This is a
Merc 3.0L straight 4. I'd "like" to think that it is
valve lash, but that "rattling", diesel-like sound has
got me worried, because in my car engine days,
this sounds just like piston slap/wrist pin type noise.
And when I really wedge my head down in the
engine compartment, it "almost" sounds like its
loudest from the back of the engine near the
flywheel/coupler, but I can't say that for sure.

Is this normal? - can someone shed some light
on the nature of this sound, and why it sounds
so much like piston/wrist pin type noise, and
not like the lifter noise of the old V-8's of years
gone by? Could it be just the physical layout
of the Merc 3.0L straight 4 and its valve train
layout? And if it is valve lash, is it normal to
need adjustment after 20-ish hours on a new
motor?. And one last question, does anyone
know for sure if the 2005 Merc 3.0L has
solid lifters, or hydralic lifters ? Is this
something that Olympic Boat centers is used
to doing in the fist few hours of new Merc 3.0L's ?

Thanks in advance!