Seawater System; Seawater Pump Impeller Inspection; Flushing And Draining The Seawater System - Mercury TDI 3.0L Operation And Maintenance Manual

Section 4 - Maintenance
4. Replace the fine element fuel filter.

Seawater System

Seawater Pump Impeller Inspection

The seawater pump impeller must be inspected (and replaced, if necessary) at the interval specified by the maintenance
schedule. It is recommended this task be performed at a Mercury Diesel authorized repair facility.
1. Close the seacock.
2. Remove the four screws on the front side of the seawater pump and remove the cover. Discard the O‑ring.
3. Mark the direction of rotation of the impeller and remove the protective cap from the middle of the impeller.
a
4. Use a suitable puller to remove the impeller from the impeller shaft.
5. Inspect the impeller for damage. The impeller must be replaced if there are any signs of damage.
NOTE: Keep an extra impeller onboard the boat at all times.
6. Lubricate the impeller with silicone spray or glycerine.
7. Push the impeller onto the shaft and press the protective cap into the impeller.
8. Insert a new O‑ring into its groove.
9. Install the cover onto the housing and secure the cover with the four screws. Tighten the screws to the specified torque.
Description
Seawater pump cover screws
10. Open the seacock.
11. Start the engine and check the cooling system for leaks.

Flushing and Draining the Seawater System

1. Close the seacock.
2. Open and clean the seawater filter.
3. Fill the seawater filter with fresh water and operate the engine at idle.
IMPORTANT: Keep the seawater filter filled with fresh water while the engine is running.
4. Operate the engine until the water draining from the engine runs clear to ensure that all sludge and salt residues are
flushed away.
Page 48
Seawater pump cover screws
c e
b d
50720
50717
f
a - Seawater pump
b - Impeller
c - Protective cap
d - O‑ring
e - Cover
f - Screw (4)
Nm lb‑in.
4.0 35.4
90-8M0133568 JUNE 2017
eng
lb‑ft
–