lower unit leaking

[sacnho]

I have a 1992 Mercury 40 that is leaking lower unit oil out of what I think are water drainage holes? This hole is 4 to 5 inches to the left of the vent hole. There are two small holes on the port side and one small hole on the starboard side. The hole it leaks out of is oblong. It only leaks out of this hole when the motor is trimmed up. Am I looking at replacing seals and if so is this a DIY job?<br /><br />Thanks

 

[Moody Blue]

Re: lower unit leaking

Sounds like either the drive shaft seals under the water pump housing and/or the shift shaft seal are leaking. Better check the lower unit oil for water contamination. I had a similar oil leak and replaced the drive shaft seals without doing the shift shaft seal. Still leaked oil so I did the shift shaft seal and problem solved. No more oil leak and no more water in the L/U.<br />Simple jobs with basic tools and some general mechanical abilities. A special tool is required to replace the shift shaft seal/bushing but that can be fabricated from a piece of steel pipe in about 2 minutes. A manual for the motor will be a requirement before you start.

 

[sacnho]

Re: lower unit leaking

Thanks Rod<br /><br />One more thing I forgot to mention, I just changed the lower unit oil 2 weeks ago. The old oil did not appear to have water in it. Is it possible that the new oil reacted some how or I did something else wrong?

 

[Moody Blue]

Re: lower unit leaking

The oil will be milky or tan colored if water has gotten in there. Any water will settle to the bottom and will drain first before any oil when you remove the fill/drain plug. The shift shaft seal is basically a one way seal to keep water out of the lower unit. If the oil is filled beyond capacity and the motor is left in the sun and gets hot for example, the oil will expand and seep past the seal and out the water drainage holes. If leakage is recurring a new seal may be in order.