Merc 50hp leaking oil

[MercMan2004]

Hi...<br /><br />I have a 1984 Merc 50 HP that appears to be leaking small amounts of oil from the lower unit.<br /><br />In particular, the oil seems to come from a small rectangular notch that is located near the edge (boat side). <br /><br />I cannot find any reference to that notch in my Seloc Repair Manual. It is located about the same level as the Lubricant Vent plug, but it is over by the leading edge of the unit. Its about half inch long and 1/4" wide. It is only on one side of the unit. There is a small circular hole just next to it. <br /><br />Does anyone know what this notch (and the circular hole) is and why oil would be coming from it?<br /><br />Could it be a gasket/seal in the lower unit that's not sealing?<br /><br />Any advice would be greatly appreciated.<br /><br />Dave

 

[WillyBWright]

Re: Merc 50hp leaking oil

Welcome to iboats, Dave.<br /><br />Not sure about the notch. There are drain holes to let water that collects in certain cavities to drain. If you're getting lube out of one, there's a seal leak nearby. I'd suspect the shift shaft seal. But there must be something forcing the lube out. If water is being forced into the gearcase from the water pump, there's a bad seal in the water pump base.<br /><br />It's always best to replace all of the seals, o-rings, and gaskets. They're all worn and replacing the worst only moves the leak to the next worst. Rebuild the water pump as long as you're there anyhow.