Volvo Penta D4 Operator's Manual page 79

Maintenance
Seawater System
The raw water system is the engine's external cooling
system. On engines with drives, the raw water pump
sucks in water via the drive, through the control sys-
tem's oil cooler to the raw water pump. The water then
passes through the raw water filter before being
pumped through the fuel cooler, intercooler, engine oil
cooler and heat exchanger. Finally the water is fed out
through the exhaust elbow, where it is mixed with the
exhaust gases.
On engines with reverse gears, the raw water pump
sucks in water via a raw water intake, after which the
water passes a raw water filter (extra equipment)
before being pumped through the intercooler, heat
exchanger, engine oil cooler and gearbox oil cooler.
Finally the water is fed out through the exhaust elbow,
where it is mixed with the exhaust gases.
WARNING!
Risk of water entry. Water will flow into the boat if any
hose, plug etc. located below the waterline is removed
when the boat is in the water. Always close the sea
cocks. If the boat does not have sea cocks the water
flow must be blocked in a safe manner. If this is not
possible, the boat must be drawn up on land before
work starts.
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