lower unit questions

bigbrad123

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I'm a relative newbee to boat ownership (3 years now). I know the basics when it comes to lower units (ie: how to change the oil :)). So last fall when I changed it the oil was milky. I know that means there's a leak and probably a bad seal. I don't have a ton of experience fixing that stuff, so I took it to "a guy" who said he changed the lower unit seals, pressure tested it, etc. Went to change it again yesterday and it was very milky white again with some metal shavings on the plug. We don't even use our boat that much (maybe 6 to 8 times per summer). It is an older motor: 1999 Johnson 135 horse. Questions: Is it common for this to happen 2 years in a row? Could it be leaking from a different spot this time? What do the metal shavings mean? I know I'll have to get it in next spring to be worked on, but what am I looking at here?
 


shorthairsrus

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shavings on the plug is normal ---- it has a magnet on it to purposely grab the shavings. The leak - - i dont know -- is your prop good?
 

bigbrad123

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shavings on the plug is normal ---- it has a magnet on it to purposely grab the shavings. The leak - - i dont know -- is your prop good?


As far as I can tell. I took that off last fall as well, no fishing line, greased it up and put it back on. Never took it off yesterday.
 

Allen

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bb, I think he was wondering if the blades were nicked up or possibly bent due to hitting something. That can unbalance a prop and whenever you have something whirling at as many RPMs as a prop, balance is important. An unbalanced prop can cause vibrations that would be hard on the lower unit seals. Otherwise, you should certainly get more than a year out of a new seal.
 

eyexer

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I would check the prop shaft to see if its bent. bent shaft distorts seals letting in water. also the gaskets on the drain and fill plugs could be bad too
 


riverview

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i had a 18hp evinrude that the impeller shaft seals were bad and caused my bottom end to milk up fopund this out after changing the prop seal.
 

bigbrad123

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bb, I think he was wondering if the blades were nicked up or possibly bent due to hitting something. That can unbalance a prop and whenever you have something whirling at as many RPMs as a prop, balance is important. An unbalanced prop can cause vibrations that would be hard on the lower unit seals. Otherwise, you should certainly get more than a year out of a new seal.

I'll have to check it closer, but I spun it a little yesterday and it didn't seem unbalanced.

- - - Updated - - -

I would check the prop shaft to see if its bent. bent shaft distorts seals letting in water. also the gaskets on the drain and fill plugs could be bad too


Good to know. I guess wherever I take it in the spring, I will have to ask them to check out the prop and prop shaft seals.
 

Sub_Elect

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If the water pump is bad or a seal in the water pump is bad then it will cause this. Google changing the water pump in an outboard.
 

eyexer

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and I wouldn't put much faith in that guy having actually pressure testing it
 

bigbrad123

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and I wouldn't put much faith in that guy having actually pressure testing it


I think that's exactly right. It was a husband of a friend of my wife's who used to work on boats and is now retired. Went with him to give it a shot. No idea if he actually knew what he was doing or not. Lesson learned.
 


nytebyte

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If it was mine I would go ahead and change out the lower unit oil and make sure to use new gaskets on the plugs. After a use or 2 next year drop the plug and see what it looks like. Sounds like just a gasket on the plugs if it had new seals.
 

johnr

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Buy a sparkly boat, problem solved.
I take mine to Paul at Dakota Sports, fixed and worry free.
Anytime I do my own repair it ruins my time after the fix, always worried if I forgot something, or if it sound funny, etc.
piece of mind is worth the few extra a shop charges.
 

Allen

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Buy a sparkly boat, problem solved.
I take mine to Paul at Dakota Sports, fixed and worry free.
Anytime I do my own repair it ruins my time after the fix, always worried if I forgot something, or if it sound funny, etc.
piece of mind is worth the few extra a shop charges.


Pfft, if I have the time and the skillset, I'd rather do it myself so I know it's done right. A few years ago I had a local boat dealership repack the bearings on the trailer while the boat was in for some other work.

Less than 500 miles later I bought two new hubs. I fugging swear they didn't even get them finger tight and may have left one of the cotter keys uninstalled. I was pissed at myself for having let someone else screw it up.
 

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