Q & A — July 2002
By Capt. Ken Kreisler
| Detonation and how to avoid it, a plugged oil filter, and more.
causes detonation, and how can it be avoided? S.W., via e-mail
One common cause is using fuel with an insufficient octane rating, but detonation can occur even with high-octane fuel, due to a variety of factors. These include ignition timing that is advanced too far, too lean a mixture (i.e., too much air per unit of fuel), and overloading, perhaps due to using a prop with too much pitch. Older engines may detonate due to excessive carbon deposits that heat up and ignite the fuel-air charge before the spark plug.
a recent oil change on my diesel, I noticed an unusual amount of debris
in the oil. What could have caused this? P.T., via e-mail
is the proper maintenance for a raw-water pump? M.B., via e-mail
diagnostic strategy is to note the amount of water that normally exits
the exhaust system at idle. If you feel this has diminished, take a closer
look at the impeller.
This article originally appeared in the January 2003 issue of Power & Motoryacht magazine.