thermastats

[grandmaster]

84 175 hp 220aeto. Know where the thermo sensors are but wher are the thermastats located. Is there just one or is there more. I also want to know what the two wire sensor is on the head about mid way down. Wondering if it's a o2 sensor.

[Ken]

The two thermostats on my 115 Yamaha are located at the top of each head assy (V-4 block). They are under the thermo covers that are held on by four bolts. Yours should be the same on that V-6 block.
Considering the age of your outboard, if you remove the thermo covers, the gaskets will probably tear - replace with new ones.
Good luck,
Ken K