Continental Motors O-470-B Operator's Manual page 58

The following procedures are recommended for preheating, start-
ing, warm-up, run-up and takeoff.
I. Select a high volume hot air heater. Small electric heaters which
are inserted into cowling "bug eye" do not appreciably warm the oil
and may result in superficial preheating. .
WARNING ..•
Superficial application ofpreheattoacold-
soaked engine can have disastrous results.
A minimum of preheat application may warm the engine enough to
permit starting but wiH not de-congeal oil in the sump, lines, cooler,
filter, etc. Typically, heat is applied to the upper portion of the
engine for a few minutes after which the engine is started and
normal operation is commenced. The operator may be given a false
sense of security by indications of oil and cylinder temperatures as a
result of preheat. Extremely hot air flowing over the cylinders and
oil temperature thermocouples may lead one to believe the engine is
quite warm; however, oil in the sump and filter are relatively remote
and will not warm as rapidly as a cylinder, for example. even when
heat is applied directly.
Oil lines are usually "lagged" with material which does an excellent
job of insulating. Congealed oil in such lines may require con-
siderable preheat. The engine may start and apparently run satis-
factorily. but can be damaged from lack of lubrication due to
congealed oil in various,parts of the system. The amount of damage
will vary and may not become evident for many hours. On the other
hand, the engine may be severely damaged and could fail shortly
following application of high power. Improper or insufficient
application of preheat and the resulting oil and cylinder tempera-
ture indications may encourage the pilot to expedite his ground
operation and commence a takeoff prematurely. This procedure
only compounds an already bad situation.
Proper procedures require thorough application of preheat to all
parts of the engine. Hot air should be applied directly to tne oil sump
and external oil lines as well as the cylinders. air intake and oil
cooler. Excessively hot air can damage non-metallic components
such as seals, hoses and drive belts, so do not attempt to hasten the
preheat process.
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