Mercury MERCRUISER, Service Manual, Page: 489 / 566

10. If installing the port exhaust manifold, install the O2 sensors.
ECT model
a - Port postcatalyst O2 sensor (ECT models only)
b - Port precatalyst O2 sensor (all models)
7/8 in. Oxygen Sensor Socket obtain locally
Description Nm lb‑in. lb‑ft
Oxygen sensor 50 – 36.8
11. If installing the starboard exhaust manifold, install the O2 sensors, and attach the shift plate, using the three mounting
screws.
ECT model
a - Starboard precatalyst O2 sensor (all
models)
b - Starboard postcatalyst O2 sensor
(ECT models only)
c - Mounting screws (two shown, one
hidden)
d - Power steering reservoir bracket
Description Nm lb‑in. lb‑ft
Oxygen sensor 50 – 36.8
12. Fill the closed‑cooling system, if equipped, with the recommended coolant/antifreeze.
13. Connect both battery cables. Be certain to connect the negative (–) cable last.
14. Upon starting the engine, inspect all exhaust and cooling hose connections for leaks.
Oxygen Sensor
51233
NOTE: Refer to the appropriate exploded view for oxygen sensor location.
a
b
56905
b
cc
c
56904
d
a
Manifolds and Elbows
90-8M0099748 eng DECEMBER 2015 © 2016 Mercury Marine Page 7B-15