Lightwin 3012 prop seal direction

[todd281]

The prop seal was leaking on my 3 HP Evinrude Lightwin . I pulled the old seal out and tried to order a replacement. [part # 300599] That part is replaced with a different seal, [part # 327031] . Which way is the new seal to be installed? sealing the water out , or sealing the oil in , or doe not really matter?

[frankr]

The seal lip (and spring if there is one) faces the oil. Now somebody will ask how about where there are two seals? One lip faces the oil, the other faces the water.

[todd281]

Thanks again Frank, I will install it that way, as I trust your advise . Is there a explanation as to why it goes that way? I ask because it seems that installing it in that direction would mean that the greater pressure comes from inside the gearcase. I can not think that there would be any heat buildup there with it being submerged. is there another cause for a increase of pressure? or is there another reason for installing it that way? Thanks again.

[frankr]

My un-official answer is “That’s the way it has always been”. The plan is to keep the oil in. If it’s full of oil the water can’t get in. Yeah, I know, it isn’t totally full, there is room for expansion. I really don’t think heat buildup is that much of an issue, but ????? On the other hand, what happens when you take the motor out of a hot car trunk and stick it in 50 degree water? Just thinking out loud.

Anyhoo,, the change to back-to-back seals on newer motors probably makes good engineering sense.

Meanwhile there was good sense behind the old owners’ manuals that said change the oil as part of a preventative maintenance schedule.

Personally, I think we are too concerned these days about a few drops of water in the oil. If it isn’t excessive, change the oil and get on with life. Just my opinions.

[billw]

Now throw Yamaha into the discussion. Most all their lower unit seals, including back to back applications, all face OUT. They use a whole different mechanical strategy, apparently. Bottom line is they get just as much water in their gear cases as any other manufacturer, it seems like to me…..and I see a whole ton of big Yamahas, on a daily basis.

Long live American manufacturing!

[crosbyman]

the seal spring is surely stainless but exposing it to a bath of oil seems better than exposing the spring to water or worst salt water .

and…. wasn’t here an opinion that the little non shifting gearcases could work fine with john Deere cornhead grease ?

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[todd281]

Thank for the replies. I only ask because I was taught to install oil seals considering the pressures from one side of the housing to the other. The spring side, or convex side, goes facing the higher pressure. I am unsure weather the high pressure here is from the inside of the housing , or outside because of the slight water pressure at such a small depth. As Frank said we are most likely worried about just a few drops of water that we should not be worried about. The real answer would probably be to get the OME seal. I was just wondering if there was something I was not considering. Like I said ,, I trust Frank , spring facing the oil.

[crosbyman]

they also make 2 lip seals one facing in one facing out

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[jeff-register]

Only exception is the 50’s Mercury motors. Crankshaft lower faces out so no water or exhaust gets into the crankcase.

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