Lower Unit Oil Leaks?

teebar

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Jul 22, 2010
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Anyone know what these two little vents are, and why they would be leaking oil?
 

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teebar

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Jul 22, 2010
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Re: Lower Unit Oil Leaks?

I have been told by the Scottguy it is a Scott McCulloch 40 HP from 1959.
 

Wingedwheel

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Jun 16, 2009
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Re: Lower Unit Oil Leaks?

Well, I'm definately no expert on that engine, but I would assume there are seals/o-rings inside your LU that probably need to be replaced. You might have to take it apart and have a look.
 

F_R

Supreme Mariner
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Jul 7, 2006
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28,195
Re: Lower Unit Oil Leaks?

I am not intimately familiar with a Scott 40 but this applies to all two stroke outboards: You put oil in the gas. Every drop of that oil goes through the engine. Some gets burned (smoke) and the rest goes out the exhaust. As it drains down through the exhaust housing, it picks up carbon particles, which turns it black. Normally the whole mess goes out into the lake and you never see it. HOWEVER, if you have been running it out of the water or in a container, the mess becomes highly visable. When you shut it down there will be oil & water mixture coming out the various drain holes.

Those holes you are looking at-----drain holes.

If you are not getting water inside the lower unit, it is not leaking.

So check the gear oil and if no water, relax. And don't be tearing it apart if it doesn't need it.
 

teebar

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Jul 22, 2010
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Re: Lower Unit Oil Leaks?

That sure explains a lot. I have already replaced the seals in the LU. I will do a quick check to make sure there is no water in it, because, just as you say, I have been running it in a tank of water. That explains all the oil in the tank.

Thanks a lot, you've all been a great help.
 

jamcc85

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Sep 9, 2010
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Re: Lower Unit Oil Leaks?

discount marine parts also told me not to run any genaric 2 cycle marine oils only use yamalube or mercury type oils. do not use synthetic. you will always have a little bit come out because these old motors did burn all the gas and oil. beleive it or not in this ara they used to mix 4 cycle oil into the gas. but it is highly recommended against.. It is a good idea to runn some mercury quick clean in your fuel mixture. you can runn it in every tank. also while you are running it in a drum take and spray mercury engine tune into the carbs be aware you will have to change the plugs after that and you will have alot of nasties in the barrel. i was having the same problem and i thought it was my lower end to.
 
M

mrcrabs

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Re: Lower Unit Oil Leaks?

Edit, That was all BS. Who makes Yamalube? who makes penzoil? Nothing wrong with synthetic, I have great luck with it and it runs well with the local corn. I switch back and forth between E/J XD 25 and penzoil XLF (same oil) and penzoil full synthetic. I like the synth better in the winter when I idle more which is why you have all that unburnt fuel mix running down the exhaust...to much test tank and not enough flat our running of which these engines were designed to do.
 

jamcc85

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Sep 9, 2010
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Re: Lower Unit Oil Leaks?

i dont disagree i think that pennsoil and yamalube and mercury oils may or may not be all the same and synthetic is great but if someone gives me a good reason not to use genaric oil i dont use it, i just use what they tell me to run, and in a motor that is 50 years old putting synthetic in it is a wast of money since the motors dont burn it all anyway. and i may be wrong but when i am looking at oil and the synthetic is twice the money as regular i choose regular seeing as the motor is going to use the same amount anyway.
 

jamcc85

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Joined
Sep 9, 2010
Messages
19
1960 scott mcculloch 40hp

1960 scott mcculloch 40hp

battery keeps running dead no charge to battery, if i unplug the wire from the regulator to the battery and test the terminal on the regulator will have 17 volts hook the wire back up and 12.3 volts
 
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