Lower Unit Oiling

A

andrewkafp

Lieutenant Commander
Joined
Mar 15, 2003
Messages
1,668
I recently became the owner of 2 OB motors 1 50hp main and 1 6hp Aux.<br />After reading the app section of the manual and looking at this link. http://www.brokeboats.com/lulube3.html <br />I proceeded to drain and fill per instructions<br />Well, no water came out of either and the oil within was clean an a nice green colour.<br />They seem to really get into things like "Make sure there's no air in the system" and "Unit MUST be full etc etc.But in the same sentence lt's "If there is water in the oil, you will have do further tests" <br />So how important is it that it is FULL ?<br />I squeezed it in until it ran out the top and the bubbles stopped, then waited half hour and squeezed a bit more in the vent hole to ensure they were both full.<br />But really... As it it used, obviously some oil will vanish, so it wont be full.<br />Don't want to trivialise too much, but isn't the lower unit just like a car diff or manual gearbox ?<br />You change the oil once in a blue moon and you get 150,000 miles of of them.
 
Joe Reeves

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Re: Lower Unit Oiling

Andrew.... If the oil is as it should be, you can ignore the other scenarios such as "air in the unit" etc. If water exists in the unit, obviously you would need to test the unit with pressurized air (7 to 12 psi) to locate the leak to correct it.<br /><br />It is important that the unit be full. Fill from the bottom until lube exits the top vent hole, then insert the top screw to create a restriction (if air can't get in, lube can't run out too quickly). Then with the drain screw ready, remove the lube tube and quickly insert the drain screw. The few drops that may escape will have no adverse effect on the unit.<br /><br />You would want to check the unit from time to time (simply loosen the drain screw somewhat) to make sure that a seal hasn't failed which would allow lube to leak out and water to enter. It's possible to pick up someones monofilament line between the propeller and the driveshaft seal which could destroy the seal in one outing (it happens).<br /><br />It's not the same as an automobile transmision etc, that is unless you constantly stick those items underwater (grin). Just couldn't resist that.
 
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