Mariner 2-stroke outboard

[morgandlm]

I've just been working on my old faithful 2.5hp outboard and found emulsified oil in the bottom end gearbox. I assume this means the shaft oil seal has failed. I removed the propeller, impeller and pump body but cannot tell whether this oil seal is combined with the bearing or separate. Are these bits serviceable? Grateful for any advice.
Morgan

 

[VicS]

It could be the prop shaft seal(s) or the vertical drive shaft seals. The former are easily damaged by fishing line so maybe the most likely to have failed. Other sources or water ingress are also possible. (the seals are often double, two seals back to back. One keeps the oil in the other the water out.)
The seals on the oil filler/level/drain plugs are said to be a common source. Do not reuse them!

You do not say what the year and model number are so I have been unable to look up exact details but the one I picked at random shows a separate single seal and bearing on the prop shaft. Replacing the seal should be no problem note which way it fits!

You will find parts diagrams on line at http://www.crowleymarine.com/index.cfm which should answer your questions. Fit a new O ring on the water pump housing.

 

[morgandlm]

Thanks VicS - a comprehensive answer.
Morgan