Volvo Penta D4 Operator's Manual page 65

Checking/Changing zinc anodes
WARNING! Risk of water entering. Close the sea-
water cock before starting work on the seawater
system.
1. Close the seawater cock.
2. Drain the seawater as described in "Draining the
seawater system".
3. Remove the zinc anodes in the heat exchanger
and the intercooler.
4. Check the zinc anodes and replace them if they
are less than 50% of their original size. Otherwise,
clean the zinc anodes with sandpaper to remove
the layer of oxide before refitting them.
IMPORTANT ! Clean with sandpaper. Use no ste-
el tools as this will impair electrical protection.
5. Fit the zinc anodes. Make sure there is good con-
tact between the anode and the metal goods.
6. Close the drain nipples.
7. Open the seawater cock before starting the engine.
8. Make sure there are no leaks.
Maintenance. Seawater system
63