Changing; Engine Coolant-350/377 Mag And Seacore 350/377 Mag; Checking - Mercury 350 MAG Manual

Section 5 - Maintenance
Air trapped in the closed cooling system can cause the engine to overheat, resulting in engine damage. Minimize the possibility
of trapping air when initially filling the closed cooling system by positioning the boat so that the front of the engine is higher than
the rear of the engine.
NOTE: Add coolant only when the engine is at normal operating temperature.
1. Remove the fill cap from the coolant recovery bottle. Inspect the gasket and replace if necessary.
IMPORTANT: Coolant flows at a high rate of speed in this closed cooling system. Higher idle speeds can trap air in the system
and make purge procedures more difficult. Operate at idle when filling the system or purging air.
2. Fill to the full mark with the specified coolant.
Tube Ref No.
Extended Life Antifreeze/
122
Coolant
3. Check the antifreeze concentration for adequate freeze protection and correct if necessary. Refer to the Specifications
section.
4. Install the fill cap to the coolant recovery bottle.

Changing

Contact your authorized Mercury MerCruiser dealer.
Engine Coolant—350/377 MAG and SeaCore 350/377 MAG

Checking

A sudden loss of pressure can cause hot coolant to boil and discharge violently resulting in serious injury from burns. Allow the
engine to cool down before removing the coolant pressure cap.
1. Remove the cap from the heat exchanger and observe the fluid level.
2. The coolant level in the heat exchanger should be at the bottom of the filler neck. If the coolant level is low, contact your
authorized Mercury MerCruiser dealer.
3. Install the cap onto the heat exchanger.
IMPORTANT: When reinstalling the pressure cap, be sure to tighten it until it seats on the filler neck.
4. With the engine at normal operating temperature, check the coolant level in the coolant recovery bottle.
Page 86
Description
a
NOTICE
Where Used
Closed cooling system
CAUTION
!
6101
Part No.
92-877770K1
a - Heat exchanger cap
90-8M0050539 MAY 2011
eng