1989 Johnson 40 HP - Leaking lower unit oil from behind prop?

[Gryph]

Hey guys, just bought a boat literally 2 hours ago. Water tested great, fired right up, comp test was 120 even on both cylinders.

Well I was loading the boat up to leave after making the deal, and noticed blackish oil leaking from what seemed to be behind the prop, down onto the skeg and then the ground.

How hard is it to replace the seals down there "prop shaft seal"? Or is it possibly just unburned 2-stroke oil as I've read in some quick searches.

Thanks guys

 

[vinmega]

Re: 1989 Johnson 40 HP - Leaking lower unit oil from behind prop?

Hey guys, just bought a boat literally 2 hours ago. Water tested great, fired right up, comp test was 120 even on both cylinders.

Well I was loading the boat up to leave after making the deal, and noticed blackish oil leaking from what seemed to be behind the prop, down onto the skeg and then the ground.

How hard is it to replace the seals down there "prop shaft seal"? Or is it possibly just unburned 2-stroke oil as I've read in some quick searches.

Thanks guys

I have a 1981 Evinrude 25hp and I have the same thing. Its most likely oil unburnt oil.

 

[Rick.]

Re: 1989 Johnson 40 HP - Leaking lower unit oil from behind prop?

No worry. Unburned oil from combustion. Enjoy you new ride. Best of luck. Rick.

 

[Gryph]

Re: 1989 Johnson 40 HP - Leaking lower unit oil from behind prop?

Thanks for the replies guys. I've never experienced this before, but then again my boats usually stay in the water all summer.

I was more freaked out because after the 30 minute drive home, when I parked, there was still some oil dripping on the ground.

 

[Gryph]

Re: 1989 Johnson 40 HP - Leaking lower unit oil from behind prop?

So I just drained the lower unit oil and it was beautiful straw coloured, some metal shavings on magnetic drain plug.

Now I went to a marina, made the 30 min drive, before doing this to get new "seals" for the drain plug and vent plug, ended up buying aftermarket allen key ones while there... Problem is these just came with nylon washers basically, and the ones I'm taking out have a true rubber seal to them, not to mention I'll lose the magnetic drain plug, kinda pissed.

Is it normal to just use nylon washers (clear plastic is what they look like) as seals? When I first went before asking about the allen drain bolts he had already just given me nylon washers.

This is what the ones I took off look like, though one of mine is magnetic

 

[boobie]

Re: 1989 Johnson 40 HP - Leaking lower unit oil from behind prop?

If you want to use the plugs shown in the pic you'll have to use the rubber orings. Don't use the nylon washers. The nylon washers require a flat surface on the drain plug.