Thread: Foot leaking oil...I think, please help..

Ok, I purchased a used boat, that is leaking foot oil, or at least I think it is. It sat in my shop for a few days before I cranked it, never leaked a drop. When I cranked it, put it in gear and ran for a few mins (yes, with water), everything sounded good. I put it back in my shop and the next day there was a small, thick puddle of black oily substance under the foot (maybe 5-6" in diameter). Well, I thought the prop seal was gone so proceeded to drain the foot oil and found that the foot oil wasn't black at all, it is, however, milky. Leaving me to believe that maybe a seal is gone, causing water to leak in. I'm trying to figure though, why one was black and thick and the other was thin and milky, clearly two different fluids. Is the fluid that comes out of the exhaust thick? I know it can be black, but didn't think it would be so thick. I was told one time that Mercury's were bad for this and that it was just unburnt oil. Could it be there's too much oil in the fuel?

Originally Posted by Derek Edge

Ok, I purchased a used boat, that is leaking foot oil, or at least I think it is. It sat in my shop for a few days before I cranked it, never leaked a drop. When I cranked it, put it in gear and ran for a few mins (yes, with water), everything sounded good. I put it back in my shop and the next day there was a small, thick puddle of black oily substance under the foot (maybe 5-6" in diameter). Well, I thought the prop seal was gone so proceeded to drain the foot oil and found that the foot oil wasn't black at all, it is, however, milky. Leaving me to believe that maybe a seal is gone, causing water to leak in. I'm trying to figure though, why one was black and thick and the other was thin and milky, clearly two different fluids. Is the fluid that comes out of the exhaust thick? I know it can be black, but didn't think it would be so thick. I was told one time that Mercury's were bad for this and that it was just unburnt oil. Could it be there's too much oil in the fuel?

Out the exhaust thick stuff just from setting up.My old Johnson usta do it every year. Milky stuff is definitely water mixed with oil. Was your engine trimmed up or tilted? If so let it down and see what comes out.

I ain't no mechanic, but crap happens to me a lot too. I am experience.

You need to remove the lower unit and have it psi tested...it will fail...but will tell you where the leak is. Will cost you a couple hunderd to have the seals all redone. Well worth it as water in the lower is BAD...as you already know. Milky can happen with only a few drops of water. If you are handy you can do the seals yourself with the service manual. It will show you alot of tools that you "have" to have..but like I said...if your handy you can do it....without the special tools in most cases.

When they psi test they will put 15 psi or so on it with a hand pump..normally screwing fitting into the drain plug. They will then see if it will hold psi for 30 mins to an hour...well of course yours has milky oil....SO...it is leaking...so they will probably just dunk it and see where the bubbles come out...this will show them the bad seal. It is MUCH easier for water to get in than for oil to get out...if you get oil leaking out you'll get ALOT of water in it. They will also pull a vacuum on it. Before and after the sealing job.

The Black you are talking about is carbon from gas/oil mix setting up in cylinders. Do a decarb soon. You will find instructions to this under FAQ at the top of this forum. That is why its black...seriously doubt it is from LU.

Have the LU resealed...or do it yourself...and do a good decarb...and GO FISHING!! Good luck...let us know if you have any other questiosn.

Oh yeah..you never have TOO much oil...lol. Yeah you'll lose plugs and coke up...and smoke ALOT But you'll still have your motor..lol.

Personally I like mine to smoke a bit at idle...makes me feel good...lol.

Are you premixing or VRO/oil injection?

I wouldn't figure overoiling...should mix 50:1

If you premix get one of those graduated bottles to put your oil in..they are REALLY handy and always right.

I would say do a good decarb...and make sure your engine is running at the upper end of its RPM range with an average load. Most engines coke up...(get carbon "black sootie stuff") loaded up in them due to excessive idling and over propping...the latter being the norm. This can lead to broken rings and failure of engine.

Check that stuff (prop and oil mix) out and do a decarb.