Mercury MERCRUISER, Service Manual, Page: 483 / 566

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
NOTE: The gasket for systems with closed cooling blocks the water ports.
3. Insert the catalyst through the gasket into the exhaust manifold.
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.
5. Tighten the fasteners to the specified torque in the sequence shown below:
1
2
3
4
50084
Elbow shown with components removed for clarity
6. On non‑ECT models: Install the oxygen sensor plug into the oxygen sensor port. Tighten it to the specified torque.
Description Nm lb‑in. lb‑ft
Screws (0.375‑16 x 2.5 hex flange head)
1st Stage 46.1 – 34
2nd Stage 46.1 – 34
7. Connect the oxygen sensor and the exhaust manifold coolant temperature (EMCT) sensor to the engine harness.
Description Nm lb‑in. lb‑ft
Oxygen sensor plug 50 – 36.8
8. Connect the water hoses in the same location they were removed:
a. On models with seawater cooling, connect the hose from the top fitting on the poppet valve to the fitting nearest to the
exhaust outlet and tighten the hose clamp to the specified torque.
b. On models with closed cooling:
• Connect the hose from the top fitting on the poppet valve to the fitting nearest the exhaust outlet.
• Connect the hose from the bottom fitting on the poppet valve to the fitting nearest the EMCT sensor.
• Tighten both hose clamps to the specified torque.
b
a
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Manifolds and Elbows
90-8M0099748 eng DECEMBER 2015 © 2016 Mercury Marine Page 7B-9