Oil Leak Between Upper and Lower Unit

[NickM8283]

I have a 1996 Mariner 115 hp 2-stroke outboard that I purchased last summer. After storing it in my garage this winter I noticed an oil leak that appears to be coming from between the upper and lower unit (see picture). It is a slow leak, and has only slightly dripped to the ground over the whole winter. I am wondering what could be causing this and if I should be concerned. Any help is appreciated, thank you!

 

[Faztbullet]

Is it gear oil or 2 stroke oil or smell like gas?

 

[NickM8283]

I am not sure, I wiped it up yesterday to get a better idea of where it is coming from. I did a gear oil change last fall before storing it and I initially thought it was from that, but this is on the opposite side of the motor. It also seems a little dark to be fresh gear oil.
I will look again today to see if I can distinguish which oil it is.

 

[Chris1956]

Just smell it. If it smells like gas or oil, it is 2 cycle oil. If it smells like rotten eggs, it is gear oil.

If gear oil, the waterpump base seal (driveshaft seal, base gasket or Oring) is likely bad. If 2 cycle oil, it is probably normal.

 

[NickM8283]

Thank you for the response, I will see later today and post an update. If it is a bad seal, is that something that absolutely needs to be replaced before taking the boat out this Spring?

 

[racerone]

Was there any water in the gear oil in the fall ?------Lower units can be pressure tested to find leaks.------But this type of leakage is normal on 2 strokes.

 

[NickM8283]

There was no water in the gear oil when I changed it. It’s good to hear this type of leakage is somewhat normal on 2-strokes. Thank you

 

[NickM8283]

It just smells like oil, doesn’t smell bad like gear oil. So I won’t worry too much about the leak. Thank you guys for your input

 

[bruceb58]

Just so you know, there is no upper unit with oil in it...just a lower unit. All you would have to do is separate the lower unit to see what is happening. You should be doing this every two years anyway to replace the impeller.

 

[Faztbullet]

Most likely oil tank is leaking...