A potential nightmare averted:
The engine that seizes (from pumping
it's oil out) may be the one you worked on.
. . .
 This
story is all about paying attention to details. It's also about
cleaning
up someone else's mess. Once you notice a non-obvious problem,
you own a piece of the
responsibility. If you can do the job properly and it won't take
too long,
you fix it. If not, you let the owner know in writing he has a
problem
that needs attention. One way or another, you've done your
duty.*
I was doing a routine inverter
install on a 32
foot sailboat. The inverter manufacturer recommends grounding the
case of
the inverter as a safety precaution. I took a look at the engine
block,
which is the mother of all grounds on a boat. The battery cable
was
connected to a fairly accessible bolt on the engine block, so I figured
I'd put
my inverter safety ground in the same place. Removing the bolt, I
noticed
something odd. The bolt threads were coated with crankcase
oil.
Looking closer, I noticed the washer under the head of the bolt was
copper
colored. The washer was also indented where the bolt head
tightened against
it. You can see all this in the photo at the left. The bolt
that was
holding the battery cable to the engine block was was originally just
sealing an
unused engine oil pressure test port. With a little too much
vibration
working against the battery cable, the bolt could loosen up. It
doesn't
take too much imagination to envision a scenario where the engine pumps
its
lubricating oil into the bilge while the boat is cruising along.
In the
photo on the right, you can see the engine oil dipstick just above the
center
the picture. The oil pressure test point is just above and the
left of the
dipstick. The battery cable lug, with a telltale black oil stain
on the
inside, is between and below them. The rusty hole to the left of
the
battery cable lug at the left edge of the picture is an unused blind,
tapped
hole in the engine block. That's probably where the cable should
have been
terminated.
When the boat was repowered from
gas to diesel
some years ago, whoever did it picked an unfortunate place to attach
the battery
cable to the engine block. Years have gone by and there hasn't
been a
problem. But they're very well could be a problem, particularly
if I
terminated one more cable under the same bolt. Probably nothing
bad would
happen. But I don't want to ever have to explain why I made a
second
ground connection at an engine oil pressure test point.
 So
I've identified a good place were both cable should be connected.
Over the
years, however, the threads in the 10 mm hole have become coated with
enough
rust you have to look closely to even see that the hole was
tapped. The
rust has to come out if a new bolt is ever going to go in.
Fortunately,
this electrician carries a set of metric taps. The lower left
photo was
taken during the process of chasing the original threads with a tap to
clean
them out.
The lower right photo shows the
happy
ending. Both the battery negative and the inverter grounding
cable are
securely fastened to the engine block with a new 10 mm bolt. The oil
pressure
test port plug is back in place. Strictly speaking, copper gasket
washers
shouldn't be reused because they work harden the first time they're put
in and
don't necessarily seal as well when they are reused. If this were
the fuel
system, I probably would have gone out and hunted down a new
washer. But this washer still had
some "squish" remaining when I tightened it down again, so I think it
will do for the engine oil system. I'm not an absolute
perfectionist.
I did scrape the paint off the
engine block where
the cable lugs were going to seat. I didn't really have to
because the
bolt made perfectly good contact with the engine block. With this
small an
engine, there's not enough starting current to heat up a bolt if it's
tightened
down properly. But I have had it happen, so I scrape the paint
off
anyway. But that's another story.
This is one example of the
totally unexpected
things that can arise in a seemingly unrelated job. And it's why
I charge
by the
hour.
* Having written all this, there
are limits to
the duty to disclose or remedy shortcomings on a
boat. I don't
feel obligated to test every bilge pump I see. If the terminals
in back of
the dash are corroded I have to assume the owner knows he has an
old boat. If
there are taped, barely supported connections visible inside the
lazarette
it's reasonable to assume the owner knows this too. Boating is an
inherently dangerous undertaking. There are no guard rails on
docks, nor
should there be.
January 18, 2007
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