Indmar 5.7L Vortec Operator's Manual page 58

Fresh water cooled engines are shipped from
the Indmar factory filled with a 50/50 mix of
Sierra brand antifreeze and water. This mix-
ture provides freeze protection down to –26° F
(-32° C). If the temperature in your area is
expected to go below this level of protection,
see your Indmar dealer to have the antifreeze
mixture adjusted for your needs.
Running your engine with your boat out of
water will damage or ruin your engine.
Damage to your engine caused by overheat-
ing is not covered by your warranty.
Most engines are cooled by the raw water outside of the
boat (Open Cooling System). For this reason, do not
start the engine when the boat is out of the water without
an engine flushing device available from your Indmar
dealer.
With Open Cooling Systems, if your engine is used in
salt, brackish, dirty or polluted water, the cooling system
must be flushed with clean water immediately to prevent
corrosion and blockage in the cooling system.
6-8
Open Cooling Systems usually consist of a raw water
intake on the bottom of the boat, a raw water pump, a
belt driven marine water pump, a thermostat to regulate
engine temperature, and various connecting hoses. The
raw water pump pulls outside water through the intake,
circulates the water through the engine and then
discharges it overboard through a hose or with the
engine exhaust.
Fresh Water (Closed) Cooling Systems
Some engines have
a closed fresh water
cooling system. In the
fresh water system
the cooling water
contains anti-freeze
and re-circulates
throughout the
engine. If your engine
is equipped with a
heat exchanger tank,
it has a fresh water
cooling system. Raw
water is pulled
through the intake
and flows through
chambers in the heat exchanger and then discharged
overboard with the engine exhaust.
INDM-B002
Figure 6.6 – Overflow Tank
Indmar Marine Engines
1