Re: mercury outboard 9.8 HP 110 1977
The drain/fill plug is on the very bottom. They are small. The vent hole is around the top portion of the lower unit, (both plugs should look identical.) Remove both. Make sure to inspect the color of your old lower unit oil. If its milky, you have a water leak somewhere. <br /> Dont let it confuse you, fill it back up from the bottom plug. Stick a squeezable bottle of 80/90 wt, whatever type specified for your lower unit, with a pointed tip lid through the bottom drain port and push fluid back into it until it gushes out the top plug. Put the top plug back in, then put the bottom plug in. <br /> Its always good to go ahead and put thread tape on your plugs for extra percaution of water leaks.<br /> Did this answer your question?
