Mercury MERCRUISER, Service Manual, Page: 408 / 566

NOTICE
Blocking the coolant flow at the heater can cause reduced engine performance or overheating. Check for continuous coolant
flow from the engine to the water circulating pump.
NOTICE
Prevent engine damage from overheating. In models equipped with closed cooling, low coolant levels may allow an air pocket
to form when the hot water heater or cabin heater is mounted higher than the fill cap on the heat exchanger. Mount the heater
lower than the fill cap of the heat exchanger and maintain the recommended coolant level.
Supply Hose Connection
IMPORTANT: For models with closed cooling, the connections at the engine are to the glycol circuit, not to the seawater circuit.
a - Location for the water supply—to the heater
Return Hose Connection
All models—water circulating pump housing
a - Cam sensor, remove connector
b - Location for the hot water return—from the heater, use 3/8
hex socket to remove
55241
a
60065
a
b
All Models
Page 6A-4 © 2016 Mercury Marine 90-8M0099748 eng DECEMBER 2015