Big Twin Gearcase Lube Question

[rennen]

Hi there,<br /><br />I have a 1963 40hp Evinrude Lark. I changed the gearcase fluid about a month ago with the high grade OMC stuff. I did not replace the nylon washer on the drainplug, as it looked really new. I noticed today that the gearcase was leaking from a small hole on the underside of the cavitation plate. The fluid was milky indicating the presence of water. The hole is just starboard of the middle and just forward of the exhaust port(or whatever that is). <br /><br />What is this hole? Have you all run into this before? is this an overflow or is it something else?

 

[Paul Moir]

Re: Big Twin Gearcase Lube Question

I belive that's simply a drain hole to allow water trapped in the lower parts of the lower unit to escape. Since that area is also open to exhaust, you'll often see unburnt fuel/oil dripping from them, mixed with water since that area is open to the sea.<br /><br />Grab some of the fluid with your fingers and smell it. If it has a gas smell to it, that's certainly what you're looking at. It could conceivably be lower unit lube from a leaking driveshaft or shift wire seal, but it's unlikely. If it were, it would stink like l/u fluid. <br /><br />Unburnt fuel/oil doesn't indicate a problem with the engine. If the engine was idled a long time before shutting it down, it can produce quite a lot. This is a common occurance with almost all 2-stroke engines.

 

[rennen]

Re: Big Twin Gearcase Lube Question

Paul You are a savior... Thanks again for your invaluable expertise.