New Drain Screw + New Gasket + Old Gasket = Water in Lower

1996 Mariner 175 Magnum EFI - Serial OG360900

Got the boat and motor about a month ago. Changed the lower unit gear oil and replaced the drain screw, vent screw and both gaskets around screws.

Afterwards, got to thinking that I had 2 old screws but only 1 old gasket. I guess I assumed it fell out and I didn't notice it.

3 weeks later (after running the boat about 5 times...never any runs longer than about 10 minutes at a time...maybe 2 hours total on the motor) I check the lower unit oil and notice it is extremely dark with a little discoloration.

I immediately drain the oil and begin investigating.

That's when I find the old gasket in the drain plug under the new gasket. So obviously this is where some water got in.

I removed the old gasket and all pieces of it and cleaned off the new gasket good. Cleaned the hole, and made sure there were no pieces there - then re-filled the lower unit with oil.

I have not ran it yet.

Had planned to run it, then drain the oil again and re-fill it with new gear oil, and then depending on what kind of shape the drained oil was in - go from there.


Is this the proper procedure?

Hopefully I caught it before it caused any damage.

Any advice is welcome, thanks.

Haze - don't feel bad.
my dad was a professional mechanic all his life and he did the
same thing when he changed the oil in our 1954 Ford (yeah, way back when)
and in his haste, he did not see the old gasket still stuck on the motor.
an hour into our trip, the oil idiot light came on and needlessly to say,
he was extremely upset at himself for such a rookie mistake.

glad you got it figured out !!
I don't know about your motor, but some outboards have a small sump cavity
below the bottom drain plug that holds a few ounces of oil and sediment.
if you can find a 1/8 or 1/4" plastic tubing, you could suck out the remaining
contaminated oil. (but is not really necessary, according to the experts).




.

Thanks Johnny - do you think I did any damage?

The gear oil I drained out was not sludgy - and still had it's lubricating ability (it seemed), so I am hoping I will be fine.

Fingers crossed..

Legally, I am not qualified to give such advice on outboards.

others more experienced than myself can give you more accurate information.
I have probably had a dozen or more similar issues with water in the oil (we all will, sooner or later)
and the way I look at it, it depends on how long you operate it and at what speeds.
many members here have bought outboards that had milky oil - - - and there is no way
to tell WHEN it started leaking, how LONG the problem has existed, and how heavy
the seller ran his motor..... just too many variables to give an educated answer.
BUT - if after getting the gasket issue resolved and the next time you run it, and there
is still milky oil, you may have a leaking seal somewhere in the mix.
Note: finding milky oil is a LOT better than finding no oil at all !!!!!!!!!!!!

jus my Dos Centavos



.