Question Sludge dripping from the lower unit

**MA Machine** · 11-07-2008, 09:23 PM

My oil is coming from the lower unit, sort of. It's a 1980 Johnson 25. The oil is not leaking around the prop or any seals. It is leaking from a very small port on the lower unit which is located higher than the top fill hole for the lower unit oil. It looks like black sludge. My manual shows the ports but makes no attempt to describe what they do nor do they show what they are connected to. I think (hoping) they are a crankcase blow-by or something and that the oil is just sludge that has ran out of the engine. I spend a great amount of time just trolling around and only lately have I been running it to the max once in a while. I checked the lower unit oil and replaced it. It looked fine. Anyone have a idea. Do you need a picture? Thanks. Rob

Dad O. · 11-07-2008, 10:06 PM

My guess would be a mixture of burnt and unburnt oil from the exhaust.

11-07-2008, 10:35 PM

I vote with Dad O. Unburnt 2-cycle oil. If you troll alot and rarely run at high speed for long enough to get everything really warm your exhaut has enough unburnt oil in it to condense in the exhaut system and then ooze out later.

**MA Machine** · 11-08-2008, 10:49 AM

that's what I'm thinking but this is not the exhaust port. It's a unexplained pen tip sized port on the side. I'm pretty sure it's unburnt fuel/oil. I'm going to have to run it real good on the next nice day we have. Thanks for the input.

packster · 11-10-2008, 03:16 PM

I posted this on another thread last week. Hope this helps!!

Quote:

That oil that is coming out of the prop may not be gear oil. In the cold water times of the year 2 strokes get a oil sludge build up from unburnt 2 stroke oil. The color is chocolate to jet black. This oil is very thick and if smelled will smell of ammonia. Gear oil will smell of gear oil. It seeps down when the motor is tilted down. It comes down the exhaust which comes out the prop. Also if you added fresh oil to the lower unit it would not come out jet black. This is completly normal and nothing to repair. A trustworthy tech will pressure check it if in question. What color was the gear oil when you drained it?

Buy the screw in pump and pump it in. In this cold weather the oil is thick enough to stand a spoon in it. Contact me if you wish about this. I hope you don't take it to Omaha Marine Center

cause you are a richer man than I.

stox4u · 11-10-2008, 05:24 PM

I have same problem with 88 30 johnson...It has a gas leak(which doesn't affect performance...yet) and collects above and comes out thru that hole...a mechanic pointed that out to me...just a mixture of gas/oil.

**MA Machine** · 11-12-2008, 10:59 PM

Quote:

Originally Posted by stox4u

I have same problem with 88 30 johnson...It has a gas leak(which doesn't affect performance...yet) and collects above and comes out thru that hole...a mechanic pointed that out to me...just a mixture of gas/oil.

You are right. I tuned up the carb and it was set way to rich. I leaned it out and would bet that will end the problem. Now I need a nice day to blow the sludge out of it.

11-07-2008, 09:23 PM	#1 (permalink)
MA Machine MA Machine is Thawing his brain out 2008 Catch and Continue Finalist Join Date: Feb 2008 Location: Lincoln NEFGA Line Recycling Volunteer Posts: 2,977 Thanks: 1,066 Thanked 1,226 Times in 632 Posts	Sludge dripping from the lower unit My oil is coming from the lower unit, sort of. It's a 1980 Johnson 25. The oil is not leaking around the prop or any seals. It is leaking from a very small port on the lower unit which is located higher than the top fill hole for the lower unit oil. It looks like black sludge. My manual shows the ports but makes no attempt to describe what they do nor do they show what they are connected to. I think (hoping) they are a crankcase blow-by or something and that the oil is just sludge that has ran out of the engine. I spend a great amount of time just trolling around and only lately have I been running it to the max once in a while. I checked the lower unit oil and replaced it. It looked fine. Anyone have a idea. Do you need a picture? Thanks. Rob __________________ The only 2 things keeping me from going pro are skill and luck.

11-07-2008, 10:06 PM	#2 (permalink)
Dad O. Dad O. is Jobless Member Join Date: Feb 2007 Location: Lake Havasu City, Az. Posts: 1,204 Thanks: 6 Thanked 141 Times in 97 Posts	My guess would be a mixture of burnt and unburnt oil from the exhaust. __________________ Photo Album

11-08-2008, 10:49 AM	#4 (permalink)
MA Machine MA Machine is Thawing his brain out 2008 Catch and Continue Finalist Join Date: Feb 2008 Location: Lincoln NEFGA Line Recycling Volunteer Posts: 2,977 Thanks: 1,066 Thanked 1,226 Times in 632 Posts	that's what I'm thinking but this is not the exhaust port. It's a unexplained pen tip sized port on the side. I'm pretty sure it's unburnt fuel/oil. I'm going to have to run it real good on the next nice day we have. Thanks for the input. __________________ The only 2 things keeping me from going pro are skill and luck.

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11-07-2008, 10:35 PM	#3 (permalink)
dupont dupont has no status. Edit Guest Posts: n/a	I vote with Dad O. Unburnt 2-cycle oil. If you troll alot and rarely run at high speed for long enough to get everything really warm your exhaut has enough unburnt oil in it to condense in the exhaut system and then ooze out later.

11-10-2008, 05:24 PM	#6 (permalink)
stox4u stox4u has no status. Member Join Date: Jul 2008 Location: Lincoln Posts: 333 Thanks: 38 Thanked 51 Times in 31 Posts	I have same problem with 88 30 johnson...It has a gas leak(which doesn't affect performance...yet) and collects above and comes out thru that hole...a mechanic pointed that out to me...just a mixture of gas/oil.