Nanni N4.115, Operator'S Manual, Page: 49 / 66

Raw water pump impel-
ler
I CAUTION
If the engine has been run wi-
thout supply of raw water, check
the raw water pump impeller.
Change it if needed.
The raw water pump impeller is an
essential component of the engine.
It should be changed regularly
along with the seal. A worn impeller
could crack and damage the cool-
ing system. Always have a spare
raw water pump impeller on board.
NOTICE: The service life of the raw
water pump impeller vary depend-
ing the operating conditions.
To extract the impeller:
1. Stop the engine, remove the
key from the panel and close the
sea cock.
2. Remove the cover of the raw
water pump.
3. Remove the gasket .
4. Mark the position of the neo-
prene impeller inside the
pump in order to install it in the
correct position in case of rein-
stallation.
5. Carefully remove the impeller
using an extractor.
6. Inspect the impeller. Check for
damaged, cracked, broken miss-
ing or flattened vanes. Change
the impeller if it is damaged.
Clean and drain the raw water
system if parts of the impeller are
missing.
7. Inspect the cover and the
gasket for corrosion or damage.
Change it if they are damaged.
8. Lubricate the inside of the
pump and the cover with water-
proof grease for rubber.
9. Install the impeller. If reinstalling
the old one, place it at the same
location using the mark done
previously. Rotate the impeller in
the same direction as the engine
rotation. Lubricate the impeller
with waterproof grease for rubber.
10. Install the gasket and the cover
on the pump housing.
11. Open the sea cock, check for
leaks. Prime the raw water sys-
tem by adding water through the
raw water filter if necessary.
12. Start the engine and check for
leaks.
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