Lower unit small leak from vent hole, what to do?

[Ryanlins]

Hi,

I have an older 72 evinrude 40hp. I changed the lower unit oil and noticed now when it gets hot the oil leaks slightly from my top vent hole. I replaced both washers top and bottom on my drain and vent plugs. No oil is leaking from anywhere else and I have only ran the motor once. The oil coming out from the top has no signs of water being in it. I used high viscosity oil. Since I have righted that screw about a 1/4 turn and that's as tight as I can go with it by hand. It hasn't leaked since, but it's only been a couple days.

I filled the oil from below with a pump style filler and had both screws open at the time. Engine was in upright position. I think I did everything right. I find it really weird it only happens during the heat of hot days, it's happened only 3times now in the past 2 weeks. It leaked about a palm sized amount on the ground. Could it be some air trapped in there expanding in the heat?

What would you guys recommend doing...I would hate to have to replace my l/u again!!?? Any ideas would be awesome. Thanks for the help. I attached a pic to help.

 

[Daviet]

Re: Lower unit small leak from vent hole, what to do?

Sounds like you did everything right, maybe there was a small piece of the old seal in the hole not allowing the new gasket to seal properly. I would keep an eye on it and see if it leaks anymore.

 

[Ryanlins]

Re: Lower unit small leak from vent hole, what to do?

I took the screw out last week and checked to make sure the old seal was completely removed. I cleaned up everything and there was no remaining pieces of old seal there. I noticed today a small amount has leaked out again during the day, enough to make a small teardrop halfway down the side of the lower unit. It just doesn't make any sense to me...should I be worried about water getting in? What could be causing this to happen? Anybody seen something like this before?

Thanks.

 

[Joe Reeves]

Re: Lower unit small leak from vent hole, what to do?

I always (ALWAYS) tighten those drain and oil level screw with a hand held impact driver & hammer. I've found it impossible to securely tighten those screws by hand.

 

[Ryanlins]

Re: Lower unit small leak from vent hole, what to do?

I always (ALWAYS) tighten those drain and oil level screw with a hand held impact driver & hammer. I've found it impossible to securely tighten those screws by hand.

Really? I'm always afraid to strip the screw so I just hand tighten. If I were to strip them out then I'd be in a pickle...

 

[Joe Reeves]

Re: Lower unit small leak from vent hole, what to do?

Really? I'm always afraid to strip the screw so I just hand tighten. If I were to strip them out then I'd be in a pickle...

It's not a beat the devil out of it scenario with the hand held impact tool.... it's used AFTER you seat the screw, then a tap or two just to really seat it.