Lower Unit Oil Leak

[onthemerrimack]

2000 Yamaha 50hp 2-stroke ob.
When I changed the lower unit oil, I tipped the motor up to make the oil drain faster. When I put the motor down, oil dripped out from the center of the prop. I dont think that any oil dripped from the drain/fill holes into the prop area.
The motor had seen one freezing night before I serviced the lower unit, but there wasnt any water in the oil.
Is there a good way to test the lower unit for leaks like applying air pressure etc. If I remove the prop and nuts would I be able to tell if there was a leak.

 

[gill]

Re: Lower Unit Oil Leak

get a pressure or vacumm tester, hook it up to the drain plug with case fitting and a tube. the unit should hold 5psi or 5 pounds of vacumm for five minutes.

 

[BaitThrower]

Re: Lower Unit Oil Leak

How did thegear oil itself look? If it wasn't milky or like custard, then probably the gearcase seals are fine. It may have been unburnt 2-stroke oil leaking from the prop.

If the gear oil was milky or like custard, then perhaps there is a broken seal in the gearcase somwhere.

 

[robert graham]

Re: Lower Unit Oil Leak

Remove prop and carefully inspect prop shaft and seal for damage or fishing line wrapped around shaft causing leak. You can clean the area thoroughly and then run motor to check for leaks. Good Luck!

 

[triumphrick]

Re: Lower Unit Oil Leak

You also should be able to just smell it. Gear oil has that nasty sulfer smell, I too think it's just residue draining from the hub...
The pressure test will let you know for sure....