MerCruiser 305 CID (5.0L) Service Manual page 767

CLOSED COOLED MODELS
On closed cooling models, the heater must be mounted lower than the fill cap on
the heat exchanger. If the heater is higher than the fill cap on the heat exchanger
and some coolant is lost from system, an air pocket may form in the closed cooling
system. This can cause the engine to overheat.
Supply Hose Connection
Return Hose Connection
Index
Page 6B-18
a - Location For Hot Water Supply Hose (Thermostat Housing As Viewed From
Above)
a - Location For Hot Water Return Hose
CAUTION
a
a
SERVICE MANUAL NUMBER 24
75503
75480
90-861327--1 OCTOBER 1999