Lower Unit Questions - 71' 800

[spidc60]

I was changing the lower unit oil on my Merc 71' 800 and noticed there are two plugs on top. One says vent, which I know is where you look to see when the oil is full. But the other is called flush. It is a plastic screw-in plug rather than a metal one...anyone know what this is? Also, are the metal screw in plugs supposed to have o-rings? Mine does not and when I drained the oil it had water in it....thanks in advance.

 

[emckelvy]

Re: Lower Unit Questions - 71' 800

The flushing screw is, as the name implies, for flushing the motor with water. You can remove this screw, attach a special flushing attachment, and flush the motor without running it.. Easier to flush with 'ear muffs' and they do a more thorough job.<br /><br />The gearcase oil drain and vent plugs should have flat gaskets, not o-rings. Cheap at the dlr and could very well be the reason for water in your gear oil.<br /><br />HTH.........ed