What Has Happened to my Verde Motor?

[Johnson David-QA2282 <David.R.Johnson@domain.elided>]

Alfisti,

I'm looking for some advice from experienced engine rebuilders.  In trying
to track down the ominous rattle or knock my Milano has been making at idle,
I finally decided to drain the oil and remove the lower sump casting.  First
piece of bad news - a lot of metallic gunge attached to the magnetic drain
plug.  Next, I found a lot more of the same sitting on the bottom of the
sump.  Thick, black sludge with a high content of small metallic powder.
The oil in the engine was clean and golden color, for comparison.  A few
larger slivers were caught in the oil pump pickup filter.

I pulled a main bearing cap and a con rod cap for further inspection.  Both
bearing shells appeared fairly little worn, suprisingly so for an 80K mile
engine (don't believe the bottom end has been rebuilt, but I'm not certain).
No signs of copper coming through, although I did not check the thickness.
But both shells, especially the main beraing shell, had a lot of small
flakes embedded in them.  Flat bits of metal up to maybe 3-4 mm across.  I
was able to gently pry off a couple flakes and they appear to be steel,
since they are attracted to a magnet (the soft bearing material is
presumably not magnetic).  The larger particles in the sump oil are also
attracted to a magnet.

I next inspected the crank journal surfaces.  Some very faint
circumferential lines were visible on the main journal, less on the big end
journal although a couple of more visible lines.  None of these lines seemed
deep enough to catch a fingernail dragged across them.  It's hard to reach
the liners with only the lower pan removed, but the surfaces looked pristine
and I could detect no scoring there.

OK, so questions.  First the obvious one: is this bad?  I'm assuming so,
since the motor is not designed to run with powdered metal in it!  I know
the soft bearing shells are supposed to absorb grit so it doesn't score the
journals, but I'd say this is way more than they are designed to handle.
Next question is, what happened?  I can see no obvious signs of damage,
although with the upper pan in place I can't see much of slugs 3 and 6,
which is where the noise appeared loudest.  What would be the most likely
cause of failure?  Spun bearing?  Disintegrating ring?  Compression seemed
slightly low on #6, but only at 145 or so with others at 180, so no hole in
the piston!  Bearing caps I checked seemed torqued to spec.

I'd also like to ask for some guidance as to what to do next.  I'm resigned
to having to pull the motor, since even if I can just replace the bearings
I'll have to do that (and it'll be an excuse to have the PO's shoddy front
end bodywork redone properly).  But before I do so, is there any other
troubleshooting I can do to help narrow down the cause?  Right now I can
button it back up and even run it if I refill the oil, so almost any test is
possible.

Once I pull the motor, what is the wise advice on the level of rebuild I'll
have to do.  New bearings are a given, I guess I'm not sure how to tell if
the crank needs to be reground though.  What I'm particularly worried about
is how to get all the metal out so it won't negate my rebuilding work.  Will
I have to dissassemble the block and have it cleaned to do this?  I'm trying
not to spend too much money on this, but I don't want to merely postpone the
bills either.  I may skip rebuilding the heads, since that has been done
about 20K miles back according to the service history (broken timing belt!),
by Spruell I think so likely done right.  I realize the final tally will
have to await full assessment of the damage when the motor is pulled, but
I'd like to get at least an idea of the minimum I need to do.  Note that the
motor has not been run much since the apparently catastrophic event which
lead to the noise abruptly appearing.

All advice and condolences appreciated, and thanks for reading my long
winded post!

Dave J.
Island Lake, IL
1987 Milano Verde (ailing)
1964 2600 Sprint (I'm actually working on it, finally!)

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