Page 234 - REPOWER REFERENCE GUIDE (2020)

Single Catalyst V8 Engines
8. Remove the catalyst and store it in a clean, dry place.

a a - Catalyst
b - Gasket

b

32227
9. Remove and discard the old gasket. Clean the mating surface on the exhaust elbows and the exhaust manifolds.
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
Seawater‑cooled models Open water ports 8M2004414
Models with closed‑cooling Blocked water ports 8M2004606
2. Insert the gasket dowels into the fastener holes on the exhaust manifold mating surface. With the dowels seated in the
fastener holes, the water ports on the gasket align with the water ports on the exhaust manifold.

a - Dowel
b - Fastener hole

b

a

51105
NOTE: The gasket for systems with closed‑cooling blocks the water ports.
3. Insert the catalyst through the gasket into the exhaust manifold.
NOTE: The elbows with 51 mm (2 in.) and 102 mm (4 in.) rise are configured for port and starboard specific application.
There is a threaded hole for the oxygen sensor on the side closest to the engine on each elbow.
4. Align the appropriate port or starboard elbow with the fastener holes. On elbows with side‑specific oxygen sensor holes,
ensure that the oxygen sensor hole is on the side closest to the center of the engine. Install the four fasteners until hand
tight, starting with the top two.

Page 7E-18 © 2019 Mercury Marine 90-8M0149179 eng NOVEMBER 2018