Brown milky lower unit oil

[M74CRAN]

It's a 1961 40hp johnson (RDSL-23), While draining the lower unit in the fall I noticed the problem, It never made it on the lake last year, I bought the boat in late summer, the previous owner let it sit for 5 years doing nothing to it, after fiddling around with it I got it to run with the lower unit in a big garbage can, Before I ran it for the first time I drained the lower unit and the oil was fine. after pulling the drain plug in the fall a little clear water came out then a milky brown rusty substance then oil, I don't know what kind of dammage I am dealing with right now, I am going to wait till spring to dig into it right now it's -9 at 10:30 AM,I am wondering what years will interchange and if anyone has an Idea what I am looking at.

 

[walleyehed]

Re: Brown milky lower unit oil

Don't worry about interchanging anything yet...<br />Condensation is the water and crud that came out first, this can be normal to some extent If it has set for some time. The seals may have taken a set as well, and may be letting some water in.<br />Might require some tear-down inspection, see what you've got and go from there.<br />Anengine that sits for a long period of time, may develope a pit ring around the prop shaft right where the seal is. If it's not TOO bad, some crocus cloth and new seals may cover it if the gears aren't badly rusted, which they shouldn't be.

 

[Paul Moir]

Re: Brown milky lower unit oil

The forward (tapered roller) and reverse (ball) bearings usually suffer if the water line is up to them in the gearcase. Normally the higher up pinion bearings and driveshaft bearings are alright since the water ends up at the bottom of the gearcase.<br />If either bearing is water damaged, they can be replaced as they're still made today. For my '62 28hp (similair gearcase) I paid ~$35 (Canadian) for the forward bearing and less than $5 for the reverse bearing from a local bearing house.<br /><br />Before you take the gearcase apart, try pumping a little air into it and submerging it to see where the leak is. An artfully carved tire valve stem and bicycle pump can be employed for this. Try to keep the pressure under 5psi.<br /><br />Many 33 and 40hp gearcases will interchange with yours. Keep your eye out for a 1965 or later unit. They have several internal updates that make them tougher gearcases including a positive shifting detent and a re-worked pinon bearing.

 

[llfish]

Re: Brown milky lower unit oil

Did you replace the little seal that fits on the drain plug. If you didn't then the water could have entered from a around the drain plug.<br /><br />Good luck

 

[M74CRAN]

Re: Brown milky lower unit oil

Yes I replaced the old hard plastic flat washer with A new o-ring and used vegtable oil to lube it up so it would not bind and bunch up.