Locating the O2 Sensor on Yamaha OX-66 225 HP

[hotajax]

I'm reading this should be cleaned annually. Owned the boat for 8 years and she runs great. I never cleaned it. Maybe it's time. Where do I find it?

 

[family affair]

Looking at the engine from the boat, you will find the sensor on the top left under an insulated plastic cover. You will need a special socket to remove the sensor. A standard O2 sensor socket will not work unless modified. The wall is too thick.

 

[Andrew93]

I bought the gasket kit, it has two gaskets that will need to be replaced after removed. If you unbolt the housing that that sensor screws into first, a few open ended wrenches will remove the sensor pretty easy, and then you can get to the sniffer tube to clean that as well. After troubleshooting all last season I found I had one bad O2 sensor, the motor would not hold a steady RPM, new sensor fixed it though.

Andrew

http://www.classicmako.com/forum/topic. ... C_ID=44060

 

[hotajax]

For Fire93Medic

Andrew: You said you bought a gasket kit that included two gaskets. I didn't see where those go from the write up on the Mako forum. Thank you. Hot Ajax

 

[Andrew93]

One is between the block and the part the O2 sensor actually screws into and the other is around the plastic cover. I am pretty sure this is the correct kit, but be sure to check the part number with your model motor. I would imagine they are all the same but never know.

http://www.ebay.com/itm/NIB-Yamaha-V6-1 ... 5k&vxp=mtr

If the motor does not have any symptoms cleaning should be good for them, but as I learned cleaning a sensor that is already bad just makes for a clean bad sensor and doesn't solve anything where I was having symptoms. There is also a harness you can buy that plugs inline to the sensors to check their operation while the motor is running and sensor in place. I put in the generic NKG equivalent and spliced int he wires to determine if that would solve my problems end of last season, which it did. Before I put the boat in I am going to replace it with an OEM and keep the NKG as a spare.