I guess I'm not much of a sailor. After
racing in doldrums for a large part
of my life, I find irresistible joy in
turning to my reliable Atomic 4 whenever
my GPS reads less than 4 knots.
A friend gave me a drifter for my
Easterly 30, but I gave it to someone
very much more committed to wind
power than I. So you will appreciate
my consternation as I watched, over a
period of months, the normal operating
temperature of my ancient, rawwater-cooled
auxiliary climb from the
optimum 150' to 165°F. Some might say
the temperature increase is normal,
considering Lake Ponchartrain water
temperature ranges from below 50°F
in winter to more than 9O°F in late
summer. And they have a point.
My Atomic 4 has a manual thermostat. I removed the spring-loaded automatic thermostat that never seemed able to cope with our lake's temperature fluctuations, and I installed a simple manual valve in its place. The thermostat (whether automatic or manual) works by
opening a coolingwater
bypass line. When the engine is cold,
the bypass is open and cooling water
bypasses the engine block and head. As the
engine warms, the thermostat gradually
closes the bypass line, forcing cooling
water through the block and head. The
140'F thermostat recommended for raw-water
operation starts opening at its rated
temperature and generally
should keep the engine temperature
in the 150° to 160°F range, which
is the maximum allowable temperature
to minimize the precipitation of certain
seawater minerals in the cooling passages.
For long motoring passages, I simply adjust the manual valve in the bypass line to get precisely the needed cooling to maintain the preferred temperature. (The acknowledged Atomic 4 guru, Don Moyer, recommends against removing the automatic thermostat even if a manual valve is installed in the bypass line. I've not followed his advice on this point and to date am pleased with my arrangement.)
But, lately, instead of my usual precise temperature control, the engine temperature had been rising, and I guessed it was time to clean the engine-
cooling passages. I needed
to clear away the accumulated rust
scale, mineral deposits, and assorted
crud that was insulating my engine
from the meager cooling capability
our hot lake water otherwise provides.
Here's how to do it.
The plan is to introduce fresh water mixed with muriatic (hydrochloric) acid into the inlet side of the engine and remove the water/acid/crud-laden mix from the cooling-water discharge at the engine-exhaust manifold.
Close the cooling-water throughhull valve. Locate the water pump. See the hose leading from the pump to the