Oil leak in lower unit?

T

titan232

Recruit
Joined
Jun 20, 2009
Messages
3
I just picked up a 1970 Evinrude Sportwin 9.5 and was doing a test run in a barrel of water. I noticed the water had oil scum in it when I was complete and there was some oily residue on the lower unit when I pulled it out of the water. I am new to outboards and was wondering if this is normal or do I have a bad seal somewhere. Also, I removed the upper gear case oil plug to check the condition of gear oil and then realized I probably should have removed the lower one instead to check the oil. Am I right on this. Oil didn't look too bad, maybe a little lighter in colour than new oil but not milky. Anyone know where this oil scum is coming from and what I should do about it?
 
bankerjohn

bankerjohn

Chief Petty Officer
Joined
Mar 21, 2008
Messages
444
Re: Oil leak in lower unit?

All 2-cycle motors expel some unburned oil/gas mixture in the exhaust, leaving an oily residue in the water, and thus on the lower unit. If the lube in the lower unit is clear (and not milky), then your gear case isn't leaking. And yes, you should check the lower unit by undoing the lower drain plug ... 'cause that's where water would accumulate after some time passes to allow any water mixed with the oil to settle.

Sounds like your motor is OK!
 
Vic.S

Vic.S

Rear Admiral
Joined
May 4, 2004
Messages
4,701
Re: Oil leak in lower unit?

Yes remove the lower plug to check for water, but if the oil is "clear and bright" then there is unlikely to be water in there.

Important to distinguish between unburnt oil from the fuel (thin oil and usually black with carbon) and oil leaking from the gearcase .

Read this item from the Engine FAQs board http://forums.iboats.com/showthread.php?t=207285
 
kenmyfam

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,385
Re: Oil leak in lower unit?

Most likely unburnt 2 stroke oil churning around the barrel. Good idea to check the lower unit oil though and if you do not know when it was last changed then change it now. If it is not milk shake like then the seals should be O.K.
 
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