I just bought this 1968, 9.5hp Evinrude, and after changing the gearcase oil, it seems to be leaking. The oil is coming out a weep hole under the cavitation plate. If I wipe if off and come back a day later the drip, is there again, however each time there is less oil. Does this mean if have a cracked lower unit? I'm not sure the oil leaking is actually 90 weight oil. Another point of interest, is that it may have been shipped upside down.
If it is coming out of the drain hole, it could be either a spill, or a cracked housing, but probably is neither one.
The spent oil from the engine runs down with water and exhaust and out the back end of the gearcase. It partly fills the midsection to cool and muffle the exhaust. When the water runs out, the oil runs slower.
It's good to know that it's not definately a crack. The previous owner may also have fogged it, and now like you say the excess oil flowing out. One other fact I didn't mention earlier was that the grease in the gearcase looked milky. So I guess I'll have to keep an eye on it.
The 9.5 unit is like most gearcases, the water usually gets in through the vent and fill plugs when the nylon flat washers fail. It really is better to replace them whenever you open the plugs. I finally started buying a bag of 50 here at iboats, just so I would have them around. (Sierra 18-42481-9)
The 1968 9.5 is easy to reseal if you ever have the desire to do it. The hardest thing is getting the screws loose that hold the skeg. I have always had to use a hand impact tool to get them started.
There are two different seal kits for 9.5 gearcases; 1967 and back (Sierra 18-2682) and 1968 and up, (Sierra 18-2683). The problem is the whole drive is interchangeable so you have to be sure which drive you have. Fortunately, the kits don't cost that much.
Any good hardware store should have them. The allen heads are are the same head size as the slotted ones so they will fit in the in the skeg. The ones I use are just a tad longer than stock so they grab a few virgin threads. I believe they are 1/4 x 20 NC.
Evinrude Gearcase leak
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