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While checking the
oil on my stern drive’s engine, I noticed what appears to be sludge
on the dipstick. What is going on, and what can I do about it? C.B.,
via e-mail
Your oil may
be contaminated or simply have been in the engine too long. (Hopefully
you have been doing your scheduled oil changes as specified by your engine
manufacturer.) Drain the oil immediately, refill with the proper oil,
and change the filter. You may want to send the old oil out for analysis
to determine the cause of the problem.
If the problem recurs
within the specified change interval, you may have a more serious problem,
including a cracked head or block or defective cylinder head gasket.
How
does galvanic corrosion occur in a diesel engine’s cooling system?
V.S., via e-mail
It’s caused by electrical current produced by the different metals
that make up the interior components of your engine and flows through
the coolant. In raw-water-cooled engines, sacrificial rods or zinc pencils
are designed to absorb the current flow, so these must be checked regularly
for deterioration and replaced when almost half is gone.
But that’s not
the only way galvanic corrosion can occur here. It also can be the result
of an exterior source. To help prevent this type of situation, the electrical
system must be designed so that all grounds are tight and free from corrosion.
Some of the more common trouble spots are improperly grounded electrical
components and a corroded ground strap connection. Regular checks and
cleaning will eliminate any potential problems.
Aluminum parts of newer
engines are more susceptible to electrolytic corrosion–the metal
requires only about one-half the electrical potential as iron to produce
the same damaging effect–so owners of such engines need to be more
watchful of this problem.
My carbureted outboard
engine has begun to misfire at idle. What should I check? C.A.,
via e-mail
Begin with
the spark plugs. They may have the incorrect gap, be fouled, or be otherwise
defective. Fouling is sometimes the result of an incorrect spark plug
heat range. Incorrect ignition timing is another possible culprit.
Also check all spark
plug wires for corrosion or poor contact and the condition of your coil
and points and condenser if so equipped.
Need help with a
maintenance problem? Write to Maintenance Q & A, Power & Motoryacht,
260 Madison Ave., 8th Fl., New York, NY 10016. Fax: (917) 256-2282. e-mail:
kkreisler@primediasi.com. No phone calls, please.
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