Seawater System - Volvo Penta D4 Operator's Manual

Seawater system

The seawater system is the boat's external cooling system. On engines with drives, the seawater pump draws in
water via the drive, through the control system oil cooler to the seawater pump, after which the water passes the
seawater filter before being pumped through the fuel cooler, intercooler, engine oil cooler and heat exchanger. Fi-
nally, the water is pumped into the exhaust pipe elbow, where it is mixed with the exhaust gases.
On engines with reverse gear, the seawater pump draws in water via the seawater inlet, after which it passes the
seawater filter (extra equipment) before being pumped through the intercooler, heat exchanger, engine oil cooler
and reverse gear oil cooler. Finally, the water is pumped into the exhaust pipe elbow, where it is mixed with the
exhaust gases.
WARNING! There is a risk that water will enter while working on the seawater system (if the boat is in the
water). Water may flow into the boat if a hose, plug or similar object located below the waterline is removed.
So always close the seawater cock. If the boat does not have a seawater cock, the flow of water must be
stopped in a safe manner. The boat must be brought up on land if this is not possible.
Checking/Replacing impeller.
WARNING! Risk for water penetration.
Remove the cover from the seawater pump and re-
move the impeller (1).
If there are cracks or other defects the impeller must
be replaced. (If the pump shaft can be turned by hand
the flange must be replaced). Lubricate the pump
housing and the inside of the cover with a little water-
proof grease for rubber.
Reinstall the impeller using a rotating movement. In-
stall the seal washers on the shaft
center. Install the cover together with a new o-ring.
Reverse gear: Open the sea cock.
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