LEAKING SHO GEAR CASE

[bgibson]

Well I went into the garage the other day and noticed a small puddle of lube under my gear case. I had changed it to store it for the winter back a month ago. I had trimmed it down to store for the winter. It appears to be leaking from under the prop. I pulled prop and the outer prop shaft seal looks good and dry. I looked down into the case and there is new lube puddled in case. If i keep the gear case trimmed up it doesnt leak but if i lower it all the way it runs out of the bottom of the case. Where is the lube coming from? Is the a carrier seal or some other seal that would cause lube to be puddled in this location?

[Randy T]

If you over fill the lower unit, the oil will seep out of the seals.

[bgibson]

I had the vent (top plug) out and filled the gear case with the lube pump in the bottom of gear case like I have a hundred times. So how could I have overfilled the case? I pumped lube into case from the bottom until the lube came out the vent hole at the top of gear case. I know I will have to pull case and carry it to a shop to pressure check it most likely. Just brainstorming....see what you guys have run into with something similar. Gear case only has about 100 hours on it.

[Randy T]

I had the vent (top plug) out and filled the gear case with the lube pump in the bottom of gear case like I have a hundred times. So how could I have overfilled the case?

Simple because the correct way is to get all the air out, and to do that you have to force oil in from the bottom until only oil comes out from that top screw. If that is what you did sometimes you put too much oil in the lower to force out the air and it seeps out the seal.

If you leave air in there then you get condensation build up inside the lower and that creates water in the oil. Also, air creates rot, so if you have been servicing you lower unit improperly and leaving air in there then your seal could be rotted a bit.

You could also have damage in you lower unit from water freezing inside there or the slightest bent prop shaft that damaged the seal as well.

[bgibson]

If you read what I had explained before then you are not making sense. I did pump from the bottom until I got pure lube from the top vent plug.

[franktank009]

What he's saying does not make sense at all and you should ignore it. Rotted air and condensation??? There's always an air gap in a gear case... Anyways make sure the problem is repeatable. Clean everything and let it sit for a few days to see if it happens again. If the oil doesn't look like it is coming from the prop shaft then it is coming from the carrier o ring. The carrier uses a single o-ring, 10$ part from simyamaha. Only crappy thing is you'll need a special tool to remove the carrier nut if you want to do it yourself. These aren't cheap. Might as well replace the prop shaft seals while your at it.

[Randy T]

If you read what I had explained before then you are not making sense. I did pump from the bottom until I got pure lube from the top vent plug.

I did read what u said, but it doesnt mean you changed corectly.

And if you did hence the other suggestions

[bgibson]

Thank you franktank!

[PlanoKeith]

LOL !!! sounds like you did it right to me. The oil can only go in one of two ways. through the top hole ( which is the wrong way ) and through the bottom the way you are supposed to put the oil in. I would take it in and get it pressure tested so you will know exactly what is happening. All gear cases have air in them. If oil comes out then water is coming in some where. Good luck

[bgibson]

Surprise it wasn't gear oil. It is crankcase oil. It is leaking from a weep hole on the underside of the cavitation plate and running down the gear case. It is brand new oil because it is amber in color and I just changed it a month ago when I winterized the boat. There is a small vent (3 slots) just above this weep hole that had some puddled crankcase oil and that's where I found the oil so far. I remember filling the new oil filter with oil and when going to install it I dropped it. I'm thinking some crankcase oil from the oil filter got splashed into the small vent (3 slots) above the cavitation plate and bleed down to the weep hole. Not sure what else would cause crankcase oil to be in this location? I have cleaned up the oil as best as I could and will watch if any more oil puddles/ leaks in that area. I may pull the gearcase just to check the top side for some kind of oil leak. I checked all around the power head with the cowling off and there is no oil present. Checked the oil dipstick and it is exactly halfway between the marks like I filled it. I am hoping I am good!

[bgibson]

Ok so looks like I have a crankcase oil leak somewhere. How could crankcase oil get into the top of the gear case? I know I will have to pull the gear case for a top side inspection but anyone have any ideas? I did pull the side cowling off and made sure the oil drain plug wasn't leaking, it was tight with no leaking. I am stumped!