Still Leaking Oil

[gsonnier]

I'm stumped. Have a '92 Mercury 25 HP 2 Stroke. Noticed that dark black oil would slowly leak out of prop after running it. Many people were saying that it could be the inner/outer oil seals in the bearing carrier. They have never been looked at or changed so I went ahead a replaced these along w/ the large O-Ring. They were in pretty bad shape and I did find old fishing line in there like many people were saying could be the problem. Got the bearing carrier back in, etc and ran the motor. The leak is worse than before. I'm positive that the leak is coming out of the exhaust tunnel (pardon my ignorance but it's the tunnel running down the lower unit that dumps just behind the bearing carrier's O-Ring and cover). Just to be sure I drained the lower unit again and the oil is as fresh as it can be. Are there other seals in the drive shaft or elsewhere that need to be replaced? I'm also seeing other posts about leaving the lower unit on its side and how this could cause the leak. Any ideas? Thanks in advance.

 

[alcan]

Re: Still Leaking Oil

Hi Greese<br /> It sounds like your Lower unit might be ok. What you need to do is test it. Do a vacuume and presure test. This will conferm right away if your L/U leaks or not. There will be no doubt. I suspect that the black oil you seeing is unburned fuel-oil, exhaust residue. The question about laying the L/U a certain way is some what vague. I suspect the posts you are refering to would be concerning 4-stroke motors. these motors have oil in the crank case like your car. this crank case need to breath. To keep the oil from pouring out the vent some manufacture recommend that they be layed down a certain way.

 

[gsonnier]

Re: Still Leaking Oil

Hi alcan. Thank you for your help and suggestion about testing the lower unit. About the residue, does this possibly indicate too rich of an oil mixture in the gas? or anything else I should be concerned with?<br /><br />Thanks again.

 

[andrewkafp]

Re: Still Leaking Oil

Do you periodically run it on muffs ? If so, it's a common occurance. My 50 did this last winter, but since she's been out on the water regularly, there is no sign of oil.

 

[gsonnier]

Re: Still Leaking Oil

Hi Redhull. Yes, she sees all of her time in saltwater so I run it on muffs everytime I get back from a trip to flush the salt. I try to keep it at a minimum, 1-2 minutes.