Mercury MERCRUISER, Service Manual, Page: 482 / 566

!
WARNING
Performing service or maintenance without first disconnecting the battery can cause product damage, personal injury, or
death due to fire, explosion, electrical shock, or unexpected engine starting. Always disconnect the battery cables from the
battery before maintaining, servicing, installing, or removing engine or drive components.
2. Disconnect the battery cables from the battery. Be certain to remove the negative (–) cable first.
3. Drain the engine coolant:
• On models with seawater cooling, drain the seawater section of the engine. Refer to
Section 1C
.
• On models with closed cooling, drain the coolant until the level is below the exhaust elbow joint area. Refer to the
Draining
procedure in
Section 6C
.
• Note the locations and connections of the hoses for reassembly.
4. Disconnect the engine exhaust hoses. Retain the hose clamps.
5. Disconnect the seawater hoses from the elbow. Retain the hose clamps.
• On models with seawater cooling, there is a single hose.
• On models with closed cooling, there are two hoses.
6. Disconnect the oxygen sensor and the exhaust manifold coolant temperature sensor from the harness.
7. Remove and retain the four fasteners securing the exhaust elbow to the manifold.
IMPORTANT: Remove the exhaust elbow carefully to ensure that the catalyst does not fall from the manifold.
8. Remove the exhaust elbow.
NOTICE
Exposing the catalyst to foreign materials such as silicone, oils, or fiberglass can chemically alter the precious metal coating
of the catalyst and compromise its ability to convert exhaust gases. Handle catalyst components in a clean environment only.
9. Remove the catalyst and store it in a clean, dry place.
10. Remove and discard the old gasket. Clean the mating surface on the exhaust elbows and the exhaust manifolds.
a - Catalyst
b - Gasket
Exhaust Elbow Installation
IMPORTANT: Foreign material on hot catalysts can damage the catalysts. Prevent material from falling into the exhaust
manifold. If material does fall into the exhaust manifold, remove the material carefully to avoid damage.
1. Select the appropriate elbow‑to‑manifold gasket for your cooling type. Refer to the table below.
Cooling Type Gasket Ports Part Number
Models with seawater cooling Open water ports 8M2004414
Models with closed cooling Blocked water ports 8M2004606
54335
a
b
Manifolds and Elbows
Page 7B-8 © 2016 Mercury Marine 90-8M0099748 eng DECEMBER 2015