Crossover for Closed Cooling—Exploded View
Ref. No. Qty. Description
Torque
Nm lb‑in. lb‑ft
1 1 Crossover assembly
2 1 O‑ring
3 1 Blue drain plug Hand tight
4 2 Screw 27.1 – 20
5 1 Crossover cap
6 1 Crossover cap gasket
7 2 Crossover seal
8 – Closed cooling identifying mark "FWC"
9 1 Temperature sensor 16.3 144.2 –
Description
The cooling system is composed of two separate subsystems: the seawater system and the closed‑cooling system. The
seawater system is similar in function to the fan used in an automobile because it absorbs heat from the closed‑cooling system
as it passes through the heat exchanger. The closed‑cooling system is similar in function to the rest of the cooling system in an
automobile.
The coolant recovery system keeps the reservoir full. Normal coolant overflow into the recovery bottle is approximately 230 ml
(7.8 fl oz) during warm‑up. The coolant recovery system draws coolant back into the reservoir from the recovery bottle as the
engine cools. While there is coolant in the recovery bottle, the reservoir should remain completely full. If not, there is a vacuum
leak, usually at the hose leaving the reservoir or the gasket under the recovery filler cap.
Within the heat exchanger, the coolant (antifreeze) flows around the outside of the cooling tubes, while seawater flows through
the inside of the cooling tubes.
Meeting the Minimum Seawater Flow Specifications
Bravo Models with Closed Cooling
Most Bravo models do not require a through‑the‑hull or through‑the‑transom seawater pickup to meet the minimum flow
specifications. See the chart, Seawater Pickups for Sterndrive Engine Models.
Bravo engine packages do not require the addition of a through‑the‑hull or through‑the‑transom seawater pickup if:
1. The sterndrive gearcase has dual water pickups.
2. The boat is capable of 64 km/h (40 mph) with the boat fully loaded and operated within the specified operating range.
Through‑the‑hull or through‑the‑transom seawater pickups are never required on Bravo models operated above the 50th
parallel of the Northern Hemisphere or below the 50th parallel of the Southern Hemisphere.
When additional water inlets are used, a Y‑fitting is installed onto the seawater pump. Refer to Installing the Y‑Fitting.
Models with Closed Cooling
Page 6C-4 © 2016 Mercury Marine 90-8M0099748 eng DECEMBER 2015
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