Seawater Pump Disassembly - Mercury MerCruiser Service Manual

All Models
Removal
IMPORTANT: Make sure that the seacock is closed or remove the boat from the water before disconnecting any hoses.
This procedure is for removal of the entire seawater pump from the engine. Note that it is not necessary to remove the
seawater pump to service the impeller or the wear plate.
1. Drain the seawater section of the cooling system.
2. Remove both of the hoses from the aft side of the seawater pump.
3. Disconnect the air hoses from the seawater pump cover with air fittings by pushing in and holding the plastic ring around
the air hose and pulling the air hose out of the fitting.
IMPORTANT: If a belt is to be reused, it should be installed in the same direction of rotation as before.
4. Remove the serpentine drive belt. Refer to Section 4C ‑ Serpentine Drive Belt.
5. Remove the one M10 x 35 hex flange screw and the one M10 hex flange nut that secure the seawater pump and bracket
to the engine, and remove the seawater pump.
Installation
1. Fasten the seawater pump and bracket to the engine. Tighten the M10 x 35 hex flange screw and the M10 hex flange nut
to the specified torque.
Description
M10 x 35 hex flange screw
M10 hex flange nut
2. Install the seawater inlet and outlet hoses. Tighten the hose clamps securely.
NOTE: The air lines for the air‑actuated drain valve are two different sizes.
3. Install the appropriate air lines into the appropriate fittings on the air‑actuated drain valve by fully inserting the air lines into
the fittings. Pull on the air lines to ensure that they are properly installed.
IMPORTANT: If a belt is to be reused, it should be installed in the same direction of rotation as before.
4. Install the serpentine drive belt. Refer to Section 4C ‑ Serpentine Drive Belt.
Without sufficient cooling water, the engine, the water pump, and other components will overheat and suffer damage. Provide
a sufficient supply of water to the water inlets during operation.
5. Supply cooling water to the engine.
6. Start the engine and check for leaks.

Seawater Pump Disassembly

Removing the snap ring from the top of the air‑actuated drain valve can allow the components to come apart forcefully,
resulting in injury or product damage. Do not try to repair the valve or remove the snap ring.
To service the wear plate or impeller:
1. If the seawater pump is still mounted to the engine:
a. Drain the seawater section of the cooling system.
IMPORTANT: If a belt is to be reused, it should be installed in the same direction of rotation as before.
b. Mark the direction of belt rotation, and remove the serpentine drive belt.
2. Remove the four screws (three long, one short) that secure the impeller housing assembly to the rear cover and bracket.
Remove the impeller housing assembly.
3. Remove the two screws that secure the housing seal with integrated wear plate to the impeller housing.
4. Remove the impeller.
To service the bearing shaft assembly, including the lip seal and rear oil seal, continue with disassembly:
1. Remove the four screws that retain the seawater pump pulley.
2. Using an appropriate puller, remove the hub from the bearing shaft assembly.
3. Remove the lip seal from the front of the seawater pump housing.
4. Remove the snap ring.
5. Press the bearing shaft assembly out of the housing from the impeller side.
Page 6A-6
NOTICE
CAUTION
!
© 2016 Mercury Marine
Nm lb‑in.
40.7 –
67.8 –
90-8M0099748 eng DECEMBER 2015
lb‑ft
30
50