lower unit fill/drain plug question?

when i drained the lower unit oil i noticed that the vent screw had a gasket on it. then when i took the fill/drain screw i noticed that it did not. Now i know that my friends out board screw doesn't have a gasket, mine is a stern drive. Is this a problem?


Could i use O rings from an auto parts or no?

3 Answers

  • 9 years ago
    Favorite Answer

    ALL outboard drain and vent screws have gaskets (seals). These seals are about a buck each, and can be purchased at any marine supply store, Cabelas, Bass Pro, etc. These seals are made of a compression type material and are 1 use only, should be changed every time you remove the drain and vent screws. They not only seal the oil in and the water out, but act as a "lock washer", preventing the screw from loosening due to vibration. Have a good look in the screw hole, your missing seal may still be there. O rings do not work.

  • eric
    Lv 5
    9 years ago

    I've had several boats over the years. One out of 4 of the outboards didn't have a gasket. I've owned two saildrives which are basically inboard motors with a lower unit, and one of those (the newest one actually) didn't have a gasket. So the absence of a gasket isn't unheard of. If there isn't a gasket, you MUST use the thread sealant (with PTFE) that comes in a tube. To be safe, buy it from a marina store or boat supply place to be sure it is marine grade.

    I would never use something purchased from an auto parts store, again, just to be on the safe side.

  • 9 years ago

    They should all have a gasket on them because without one you will get water in your lower unit.Most lower units use a gasket but there are a couple that do use on o ring.The gaskets are not expensive maybe a buck or two at most so you should use the proper ones to ensure you have no water get into your drive.

Still have questions? Get your answers by asking now.