Page 260 - REPOWER REFERENCE GUIDE (2020)

8.1L/496/8.2L Triple Catalyst
8.1L/496 Engine
Description Nm lb‑in. lb‑ft
Exhaust manifold screws (8) 31 – 23
5. Install any components previously removed.
6. Install the collector as described in Collector Installation.
7. Install the riser or tip as described in Riser Installation.
8. Install all coolant and exhaust hoses.
9. Connect the oxygen sensor to the engine harness.
Collector Installation

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.
1. Remove any gasket material from all mating surfaces on the manifold and collector.
2. Install a new collector gasket.
IMPORTANT: The catalyst retaining rings use friction to retain the catalyst in the collector for assembly. Over time, the
interference fit of these rings may weaken, causing the catalysts to fall from the collector. Take care not to drop the
catalysts during assembly or disassembly and replace the retaining rings before installation.
3. Replace any worn or loose catalyst retaining rings.
4. Secure the catalysts into the collector. The retaining rings should prevent the catalysts from falling.
5. Install the collector onto the manifold and gasket. Tighten the 10 retaining screws to the specified torque.
Description Nm lb‑in. lb‑ft
Exhaust collector screws (M8 x 35) (10) 37 – 27
6. Repeat this procedure for the other manifold if it was removed.
7. To install the risers, refer to Riser Installation.
Riser Installation

IMPORTANT: Foreign material on hot catalysts can damage the catalysts and their ability to work properly. Prevent material
from falling into the exhaust collector. If material does fall into the exhaust collector, use care when removing the material to
prevent damaging the catalysts.
1. Remove the gasket. Discard the gasket and clean the riser and collector mating surfaces.

ECT exhaust collector mating surface
a - Dowel holes
a b - Fastener holes

b b
a

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Page 7G-12 © 2019 Mercury Marine 90-8M0149179 eng NOVEMBER 2018