Motor oil in lower unit oil

[I m askin]

Draining lower unit if 15 hp mercury 4 stroke. The oil looked milky and black. There wasn't much oil in the crankcase when I drained it for the season. Is it possible and what would cause engine oil migrating into thrower unit

 

[racerone]

Not possible.--------Just means that your motor has been neglected I would say.

 

[stresspoint]

guessing the oil is black because it is worn out .
give it a flush with some acetone , replenish with the correct amount and weight of new gear oil and run it .

 

[racerone]

??---Acetone ??-----Little varsol / paint thinner would do.------Or just let it drain for a day and refill.-----Refill from bottom till it comes out the vent.

 

[I m askin]

guessing the oil is black because it is worn out .
give it a flush with some acetone , replenish with the correct amount and weight of new gear oil and run it .

Thanks. I change it every fall with Mercury gear oil.

 

[roscoe]

Milky means water intrusion. pressure test for leaking seal.

 

[airshot]

When ever I flush a lower unit, I use kerosene, not acetone. Kerosene is actually an oil so no harm will be done, acetone can damage any seal it comes in contact with. While the lower unit is filled with kerosene, turn the motor over either by hand or with electric starter, just dont let it run!!! This will help wash any crud and old oil out. Let it drain for a while, then refill and check ( pressure test) for leaks....

 

[stresspoint]

i feel must chime back in here .
to those with negative response to use acetone to flush lowers after water intrusion and dirty detreated oil.

there are a couple of reasons my choice of poison to use acetone , the "number one is it totally evaporates" in a short while leaving very little oil residue after a flush or 2 .
because there are only small holes for evaporation the acetone is a belter choice than oil product's such as kero , petrol or diesel ,
last thing you want is your new oil specifically formulated for lower units diluting with an oil product .
it also a cheap solvent.

 

[racerone]

Just let it drain for 24 frs.----Refill with good gear oil.-------No need to flush at all.

 

[stresspoint]

Just let it drain for 24 frs.----Refill with good gear oil.-------No need to flush at all.

yea my take exactly in normal circumstances , however iv seen some pretty gluggy oil with who knows what mixed in drip from lowers , a couple of litres of the good old acetone , a quick swish around and a few hours to drain and they are good to refill with choice of oil .

i am hesitant to use anything other than the acetone because of the risk of damaging seals .

 

[topgun3690]

Put some cheap Walmart lube in it....run it...drain it. Then put in your high dollar lube. No seal damage and no cross contamination from other fluids.

 

[Chris1956]

My Wallyworld no longer carries the cheep stuff.......
I have therefore graduated to the good stuff.....

 

[topgun3690]

Quicksilver 90W nearly $20 a quart now.....

 

[racerone]

All oil products have taken me by surprise with increasing costs.-----Some say the additives are the reason.