Lower Unit question

[fatherof4]

When i was cleaning my boat up Saturday night i noticed some dark oil that had leaked out of the lower unit- i think it came form the prop area.

1.Is there an easy way to tell if the seals are bad?

2.It does not apprear to have any water in it just dark redish black in color.

[fatherof4]

My boat had a Johnson 100 2 stroke.

[blr3a]

It is possible that what you are seeing is oil left over from the exhaust. (Assuming it is a 2-stroke). 2-stroke outboards burn oil with the gas and the prop is where the exhaust comes out. As you can imagine, oil is not as combustible as gasoline, so there is usually residue and or unburnt oil that remains in that area sometimes, depending on how rich your oil to gas ratio is and it can also be affected by how rich or lean your carbs are running OR... it can be affected by a fouled out plug.

The easiest way to check your seals would be to FIRST check the oil level in your lower unit and seeing if any oil comes out the VENT hole when the engine is slightly tilted. THEN seeing if the oil inside looks milky by letting a "sample" size out of the FILL hole on the bottom. If there is any question about it being milky, I suggest just draining it all and replacing it with new oil. It should be somewhere between how oil looks new and black. Don't be concerned if it is pitch black and smells aweful, just replace the oil!

[blr3a]

Just saw your update... so my two-stroke assumption was correct

[fatherof4]

the oil only comes out when the motor is trimmed all the way down. It does not appear to be coming out of the vent hole but the prop housing.

[blr3a]

The oil only coming out when the motor is all the way down doesn't really mean anything. The lower unit is cupped behind the prop, so any oil that comes out while it is tilted up will "sit" in the cup until tilted down. This could be oil coming out of the prop shaft seal or oil draining from the exhaust.

The Vent hole I was talking about is up on the side of the lower unit. It will be a large screw that must be removed with a large Flat Head Screwdriver. It is usually about 6 to 10 inches above where the prop shaft would be. Be careful though, most of these screws are aluminum so make sure you get a screw driver or bit that fits it good before torquing on it.

Originally Posted by blr3a

It is possible that what you are seeing is oil left over from the exhaust. (Assuming it is a 2-stroke). 2-stroke outboards burn oil with the gas and the prop is where the exhaust comes out. As you can imagine, oil is not as combustible as gasoline, so there is usually residue and or unburnt oil that remains in that area sometimes, depending on how rich your oil to gas ratio is and it can also be affected by how rich or lean your carbs are running OR... it can be affected by a fouled out plug.

The easiest way to check your seals would be to FIRST check the oil level in your lower unit and seeing if any oil comes out the VENT hole when the engine is slightly tilted. THEN seeing if the oil inside looks milky by letting a "sample" size out of the FILL hole on the bottom. If there is any question about it being milky, I suggest just draining it all and replacing it with new oil. It should be somewhere between how oil looks new and black. Don't be concerned if it is pitch black and smells aweful, just replace the oil!

Blr3a gave you some good advice on checking your lower unit oil. I might add that the "fill plug" should have a small magnet on it. There will be a few small particles of metal on it. That would be normal wear. If there are any chunks or large amounts of small particles you might have a problem. When I remove the bottom plug I try to catch the first few ounces of oil for inspection. A clear water bottle works great for this. I look for water when I first loosen the screw. Then it might be milky if the boat has been used recently. The oil and water will separate if it sets for a long while. You can buy a lower unit pump at a boat dealership, BassPro and some Wal-Marts carry them. Academy Sports have them too. They should be inexpensive.
If your lower unit is leaking oil I would have the work done at a reputable shop. I would recommend replacing the impeller " water pump" while they are in there too.
That reminds me........I need to change my oil too.

[tkwalker]

Okay, guys how about ya'll coming to work for me ...All correct answers ... Note: After running your motor wait 3 three days to let the water and oil seperate. The oil will settle to the bottom ... Leave the vent plug in (The one at the top) Remove the lower fill plug and the water will come out first ... Depending on the amount ... you may just add new lower unit Hypo .... <'TK><

[blr3a]

Hey TK... I think I have something that may interest you!!!



This is a carb and fuel pump rebuild kit for your antique Johnson/Evinrudes. I have not looked in my book to see what all they fit, but I had a 1959 Johnson 35 SeaHorse and a 1959 Evinrude Lark (as you already know, same engine). I kept this kit in my dry box at all times. I probably put 1000 hours on that old Lark, it was locked up when I got it and I completely rebuilt it top to bottom. (It was my first boat and I wasn't afraid to take it ANYWHERE!) Anyways, it is gone now so if you have a use for this let me know, you can have it. BTW... I am looking for short shaft lower unit for a 1969 Mercury 20 horse... maybe you can give me a discount

[SAMBOLIE]

Originally Posted by fatherof4

My boat had a Johnson 100 2 stroke.

It is always nice to tell others that you have a big Johnson.

[tkwalker]

Originally Posted by blr3a

Hey TK... I think I have something that may interest you!!!



This is a carb and fuel pump rebuild kit for your antique Johnson/Evinrudes. I have not looked in my book to see what all they fit, but I had a 1959 Johnson 35 SeaHorse and a 1959 Evinrude Lark (as you already know, same engine). I kept this kit in my dry box at all times. I probably put 1000 hours on that old Lark, it was locked up when I got it and I completely rebuilt it top to bottom. (It was my first boat and I wasn't afraid to take it ANYWHERE!) Anyways, it is gone now so if you have a use for this let me know, you can have it. BTW... I am looking for short shaft lower unit for a 1969 Mercury 20 horse... maybe you can give me a discount

Yep, That is a good kit, I am a Sierra dealer but buy BRP parts on certain items ... ... I am working on a Merc 20HP for a dealer who will want to sell it ... I think it is the vintage you are looking for ... The last year they used internal coils instead of External .... <'TK><