lower unit question about oil and water

[jwilkey84]

My recently acquired 1958 merc keikhaefer 58A seems to have problems with water entering into the lower unit oil, as it is milky after I water tested it. So I took the lower unit off of my other parts motor and was looking it over to see if I wanted to just swap the two. I got to looking, and when I poke a screwdriver into the top oil hole I can see the screwdriver when I look down the rubber tube where the impellor pumps water up to the engine. Am I missing something or does that tell me that this lower unit as well will let water into the oil? That isn't normal is it? I just don't want to swap the two to find out that this one leaks too?

 

[Yepblaze]

Re: lower unit question about oil and water

You are poking a screwdriver in a hole labeled flush. It goes directly into the waterpump are and in the real world doesn't get used at all. Put the plug back in there. The vent hole is a small screwdriver screw, behind propeller at the top of the wedged section below cavitation plate.


And if you have determined that there is a leak by the oooze left on the ground after running, you could be chasing a non-issue.

Most gear oil has a foamy appearance untill any air settles out, and I have seen that before.


Sometimes those old motors got filled with white runny grease too.

 

[jwilkey84]

Re: lower unit question about oil and water

I am confused, I thought you filled the lower unit with oil through the big screw at the bottom until oil came out the big screw at the top. At any rate my oil isnt foamy, just milky, and that is after it has sat a day after running. What does the little screw below the cavitation plate do?

 

[diaric]

Re: lower unit question about oil and water

you should have 2 or 3 screws. 3rd screw if u have it is usually bigger and labeled flush.used to flush out unit and pump from sand and salt water. not used much any more. bottom screw is fill, top is vent. pump lube in bottom till it flows out vent then replace screw. replace screw seals as this is a commom place for water to seep in your lube oil

 

[jwilkey84]

Re: lower unit question about oil and water

soooo...like I said before, i can stick a screwdriver through the vent screw hole and see it when I look down the water tube that sends water to the engine. Can't the water and oil mix there if I can physically see that there is no barrier between the water way and the oil?

 

[jebeebe]

Re: lower unit question about oil and water

soooo...like I said before, i can stick a screwdriver through the vent screw hole and see it when I look down the water tube that sends water to the engine. Can't the water and oil mix there if I can physically see that there is no barrier between the water way and the oil?

my 60hp only has 2 screw holes. The bottom one is the fill and the top one is where the oil oozes up though a tapered berring and out the vent hole. The water pump lower houseing has a O-ring around it and an inner seal that keeps water out of that area. I don't think you should be able to see the screwdriver through the water pump outlet unless there is a third hole????

 

[jwilkey84]

Re: lower unit question about oil and water

i'm sorry. There are 3 holes. The big one at the very bottom, one at the very top that is the same size as the bottom one that says flush, and one smaller one just below the flush hole. I can see the screwdriver when i stick it in the flush hole. is that normal?

 

[Yepblaze]

Re: lower unit question about oil and water

Put the big screw plug back in, and use the little screw I told you about to vent while you fill the lower unit.

Some people still like to use Lubriplate runney milky/white grease in those lower units. I think it might even be on the motor's label.

I like marine grade gear oil, and usually spend the money on the high performance green stuff from Mercury, but that's me.


A common seal failure was under the water pump, but to access that requires some dissasembly and He-Man maneuvers getting things apart.

Tear the valve stem out of a bicycle tube and grind the torn end into a blunt taper.

Drain lower unit well, replace vent screw, and screw tire valve stem in drain hole. Put a slight pressure in the unit with 1/2 a pump +- or so, off of a bicycle pump.

Place unit in pail of water and look for bubbles.

 

[Motor Boater Bill]

Re: lower unit question about oil and water

You can also drain the oil and let it sit in a glass or plastic jar until the water settles out, but that will only verify water in the oil. The bubble test will tell you where it is leaking. Don't use too much pressure. Five psi should bubble if you have a leak. The LU should hold 10 to 15 psi, but at those pressures it may also cause weak seals to push closed and make a leaking seal appear good. I like to put air in a tank at whatever pressure I am testing with and use that to pressurize the LU, so I know what pressure I am putting in. You might also want to rotate the shafts while under pressure and under water. Hope that helps.