How do I change lower end oil in 50 HP?

I have a 1982 Johnson 50 HP outboard motor. I want to change the lower end oil and do not know where this is or how to do it. I have a vent screw on the motor but that is it. Can someone please help me? Thanks.

Re: How do I change lower end oil in 50 HP?

drain screw is further down, you do have one.

Changing lower unit oil

There are 2 straight slot screw on the starboard side of the lower unit. Top is vent plug, bottom, drain and fill plug. ( do not touch Phillips head screw).

Remove the bottom plug, put container under lower unit, now remove the vent plug, while the oil is draining, replace the seals on the plugs part # 311598, buy several of these, ( they are a one time use item)

Walmart and many places sell a little hand pump. To use to fill the unit, you insert the tube into the bottom hole, and pump till oil reaches the vent hole. Install the vent screw, then remove hose, install the drain-fill screw, clean up mess.

The screws can be hard to get out, do not mess up the head. You may need to employ an impact screw driver to break them loose.

Re: How do I change lower end oil in 50 HP?

Welcome to iboats!!!!

Down near the bottom of the lower unit are two screws. The lower one is down near the skeg, or the rudderlike fin on the very bottom. They should be slotted to accept a standard sctrewdriver. I dont remember if your motor has a phillips head screw on the lower unit or not. If there is one there DON'T TOUCH IT. LEAVE IT ALONE!!

Put a large coffee can or similar container under the skeg to catch the oil as it drains. Remove the lower screw and replace and discard the old seal. Now, you haven't given a model number, but I believe on all johnsons of this vintage the top screw is just under the ventilation plate on the same side of the outboard. The ventilation plate is the horizontal piece that runs around the lower unit that should be, or very close to being, flush with the bottom of the boat.

Remove the top screw and replace the seal. The oil should be draining now. Check it for water. Check it for metal shavings and metal pieces. Rub a little between your thumb and forefinger to feel for grit and metal shavings.

After it has drained out, wipe the lower unit down to remove the old oil. You will need to purchase at least two containers of lower unit lubricant.

Inject the lube through the BOTTOM hole. Air will escape through the top hole while the unit is being filled. When the lower unit is full oil will come out of the top hole. While holding the bottle still in the bottom hole, re-install the top screw. Now remove the oil bottle and re-install the bottom screw.

Vaccuum will be created when you install the top screw and not allow the oil to drain out while your installing the bottom screw.