Can LU oil leak out with no water getting in?

[Home Cookin']

I checked my LU this weekend after some funky sounds going on and found that it drained out a half quart although it holds a little more than a quart. The oil was very black and stinky, but no evidence of water (not milky, not white, not streaked. Drained w/in an hour of running it.)

So the first question is: can it leak out/burn up/run low without water intrusion?

BTW I filled it in the Spring; maybe ran 40 hours since, maybe less.

On top of that: the bottom screw won't seat; goes in half way and jams. I don;t want to force it and strip anything. May have to tap out the threads?

On top of that: pulled lots of filings out on the magnet. I had some rough running then it ran OK but sounded like there was a rattle--hard to tell where it was coming from and you know how it is when you start listening....

On top of that: pulled about 3" of what may be string out. Could a piece of line, maybe braid, work its way in thriough the seals? and not let water in?

this LU is an aftermarket I put on new about 2 years ago; 2003 Yamaha 150. I put 75-100 hours a year on it, which is nothing around here and for those motors.

Because the boat is kept in the water I can't check the LU often, but anyway it's my belief that one shouldn't have to, unless problems appear.

Doesn't sound good, does it?

 

[Daviet]

Re: Can LU oil leak out with no water getting in?

If the lower unit builds pressure in it, it can blow the oil past a seal and not let water in.
And yes, it doesn't sound good.

 

[matt167]

Re: Can LU oil leak out with no water getting in?

not only that, seals can fail one way and still hold in the other, so it's entirely possible

 

[Sea Rider]

Re: Can LU oil leak out with no water getting in?

When LU is new and after first oil change, you should see small quantities of metal fillings, that's quite normal, internal gears are setting in. But if there's a huge quantity of metal fillings there's something wrong with internal gears, probably adjusted too tight and wearing out between them with use. Replace bottom filling screw with new one, check if LU' female threads are worn as to sit bolt tight back. Fishing lines can damage lower oil seals if caught between seal and prop body.

Happy Boating

 

[Home Cookin']

Re: Can LU oil leak out with no water getting in?

thanks

what kind of pressure would build in a LU?

but speaking of which, when I filled it, I pumped in from the bottom with the top screw loose. I heard air coming out and then got some new oil oozing out, so I tightened the top, and when I pulled the pump off the bottom, got a jet of fluid out from pressure. I found that odd.

 

[Sea Rider]

Re: Can LU oil leak out with no water getting in?

When changing LU oil with manual pump with exact same filling procedure, there's always a small oil loss when pulling pump from bottom, kind of inertia thing, not really a pressure issue, will need to remove filling connector and inmediately tap lower hole with finger, remove finger and screw bolt back the fastest as possible...

Happy Boating

 

[dingbat]

Re: Can LU oil leak out with no water getting in?

thanks

what kind of pressure would build in a LU?

Actually, it can be quite high, relatively speaking. Even more so if the unit is half full of air since air expands at a rate 3 times greater than oil.

but speaking of which, when I filled it, I pumped in from the bottom with the top screw loose. I heard air coming out and then got some new oil oozing out, so I tightened the top, and when I pulled the pump off the bottom, got a jet of fluid out from pressure. I found that odd.

Sound like you still have a bunch of air in the LU. When I change mine, I completely remove the upper screw and let it sit for a while to let the air work it's way to the top. I then put my finger over the upper hole to create a vacuum while installing the lower plug.

 

[Frank Acampora]

Re: Can LU oil leak out with no water getting in?

Metal filings and noise? Leaking lubricant? You are foolish if you do not open up the lower unit for inspection. It is trying to tell you something.