MAINTENANCE
SERVICE MANUAL NUMBER 25
90-861328--1 NOVEMBER 1999
Page 1B-35
8. After seawater section of cooling system has been drained completely:
a. Install all drain plugs and tighten securely.
b. Reconnect hoses and tighten all hose clamps securely.
c. If NOT equipped with seacock: Seawater inlet hose must remain disconnected
and plugged until engine is to be restarted.
IMPORTANT: Mercury MerCruiser recommends that propylene glycol antifreeze
(nontoxic and biodegradable) be used in seawater section of the cooling system for
cold weather or extended storage. Make sure that the propylene glycol antifreeze
contains a rust inhibitor and is recommended for use in marine engines. Be certain
to follow the propylene glycol manufacturer’s recommendations.
9. For additional assurance against freezing and corrosion in the internal water passages:
a. Remove the thermostat cover and thermostat.
b. Fill the engine seawater cooling system with a mixture of antifreeze and tap water
mixed to manufacturer’s recommendation to protect engine to the lowest tempera-
ture to which it will be exposed during cold weather or extended storage.
c. Using a new gasket, reinstall thermostat and cover. Tighten cover bolts to 30 lb-ft
(41 Nm).
NOTE: Hoses shown removed for visual clarity. Do not remove hoses.
74493
a
b
c
d
e
a -
Housing
b -
Gasket
c -
Thermostat
d -
Spacer
e -
Fill Here
