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mudslinger64

lower unit leaking lube

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after being on the lake today i was putting the boat away and i noticed lube was leaking from a hole by the upper plug hole on the lower unit.it was slightly higher than the plug and to the rear of it a little,is this a frost plug that popped?when i drained the lower unit this spring there was some water in it.i can't see any cracks anywhere it is only coming out of that little hole.the motor is a 1979 johnson 25 hp.

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smell it and verify it is lower unit oil. If it smells like gas it is unburned gas oil mix which is common when you trim your motor for the road. If you are sure it is lower unit oil likely places are drain and vent plug gaskets, Prop shaft seal, drive shaft seal and shift seal. The prop shaft is the most common cause fishing line can get wrapped there and will damage the seal. If motor is from 79 it is probably due to have a new seal kit installed. Wait till later in the season when the marinas get caught up. Just keep monitoring it and add more oil as needed till you get it fixed.

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i think your right about the unburnt gas and oil,i just went and looked at it again it looks greyish black and there is a little coming out of the exhaust hole also.i cracked open the drain for the lower unit and the lube that came out had a brownish yellow color to it not even close to the color of what is leaking out the side thanks i was getting worried.

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When you trim your motor the float in the carb has a tough time fighting the new gravity and a lot of times will loose causing the needle valve to open. Because when you shut your motor down your fuel lines were pressurized fuel will free flow out the carb and down the motor leg. When it mixes with water it tends to get a puss look and frothy. The best way to tell is to smell it. Nothing stinks like lower unit oil. If it smells like gas dont worry about it

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Quote:

when i drained the lower unit this spring there was some water in it.


You may have dodged a bullet here... you really should be draining and re-filling your lower unit lub in fall. The reasoning behind it is if you have water in your lower unit and let it sit outside over the winter the water will freeze and either damage a seal or crack the lower unit.

Keep an eye on it and check your lower unit lube periodically to see if your lube turns milky.

marine_man

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