Oil injection tank

[reloader51]

I have a 2004 Mercury 115 2 stroke with oil injection tank on motor. There is a rubber plug on top of the oil tank. Should it be open or closed during operation? Thanks!!

 

[fitz73222]

That should be a vent and open

 

[reloader51]

Thank you. Any idea when it would need to be closed?

 

[R_P]

Serial number? Look up the parts diagram of your engine and see what part you are referring to in the oil tank diagram

 

[reloader51]

19299A1

 

[fitz73222]

That is a vent, it has an internal reed to allow air to enter the tank as the oil drops down during use...It is not a plug.

 

[reloader51]

Thank you

 

[Texasmark]

That is a vent, it has an internal reed to allow air to enter the tank as the oil drops down during use...It is not a plug.

Interesting. I understand the physics of allowing air to replace fluid as the fluid level drops. My curiosity revolves around the fact that my 2002 didn't have that plug and the oil tank worked just fine. There was even a reminder in that if you filled the tank, tilted the engine all the way up and your fill port rubber gasket was "leaking", the interior of the engine compartment would accumulate a good deal of oil.

Does the new "port" have a one way check valve?

 

[Droid]

You're over thinking it. It vents but stops oil from leaking when tilted.
Also, that is not a serial number nor does it appear to be a valid part number.
Fill the tank with quality oil & go boating.