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Maintenance: Rawwater system
Checking/Changing rawwater
pump impeller
IMPORTANT! Always keep a spare impeller and
gasket in store aboard the ship.
1. Drain the external cooling water as described in
the chapter draining the rawwater system.
2. Remove the pump end cover. Remove the impell-
er using a puller, remember direction of rotation.
3. Inspect the impeller. Change the impeller if there
are any visible cracks or other defects.
4. Clean the inside of the housing.
5. Put some grease on the impeller blades and push
the impeller into position while rotating it in the
normal operating direction.
6. Fit the cover with a new o-ring or gasket.
7. Close the drain cocks.
8. Open the rawwater cocks.
Cleaning the heat exchanger
Clean if there are signs of clogging, a gradual increase
in engine temperature or high rawwater pressure.
Check/clean the rawwater filter first. Also check for
other damages on the heat exchanger.
1. Drain the external cooling water as described in
the chapter draining the rawwater system.
2. Detach the pipe connections from the heat ex-
changer.
3. Remove both covers from the heat exchanger
4. Clean the heat exchanger tubes using suitable
brushes while flushing the tubes with water
5. Refit the heat exchanger element and mound the
covers.
6. Connect the pipe connections to the heat exchan-
ger. Check gaskets and change if necessary.
7. Open the rawwater cocks. Fill the freshwater sys-
tem.
8. Start the engine and make sure the rawwater sys-
tem is not leaking.
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