Obvious gearcase leak?

[Greenporter]

90hp Johnson 2006
Forgive my stupity. When I flush my engine with fresh water at the end of the the day every once in a while I notice a small streak of oil coming from the top of my lower unit (just a couple of times from June-Sept.).

At the end of the season I changed my gearcase lube with Johnson lubricant which is green. I fogged the engine and soon after a small streak of green came out of the top of the lower unit. (note: drained lubricant looked pretty good - no water and not milky).

Does this sound like a seal problem?

 

[OptsyEagle]

Re: Obvious gearcase leak?

Most likely this is just unburnt oil residue from your exhaust. It is more prevalent when you run the motor without a load (on muffs or in a barrel) and especially when you fog the motor.

When I fog my 9.9Hp, it drips this blackish residue for weeks. This is normal though.

 

[Greenporter]

Re: Obvious gearcase leak?

Thanks for your response OptsyEagle

even though it was clearly the exact green lube that was just put into the gearcase? this isn't coming through the propeller... it's coming through the seem where the lower unit meets the upper. not a lot but it definitly is there.

 

[OptsyEagle]

Re: Obvious gearcase leak?

Well, I can't say for sure that it is not a gear oil leak. The liquid that comes out of mine is so mixed with water that it is hard to tell the exact colour. Since my gear oil is brown, I can surmise that it is not it. Unburnt exhaust will leak in a few places.

You do have a couple of options. The safest option is to drain the gear oil and conduct a vacuum and pressure test. You will need some specific equipment and if you search this site, you should find the procedure.

If it was me, I would run it for a few hours in water and then drain the gear oil again and verify if any water is getting in, either by determining if it is milky white or if I actually see water. If you leave the motor for a few days after use and then drain it, any water should drop to the bottom and if no water comes out right away (when you remove the drain plug only), you are good to go and don't need to refill the entire case again. Maybe top up what was lost.

If some water does come out, you have a leak. You can either re-seal (not a fun job if you do it yourself) the lower unit or just plan on changing the oil more frequently. This would depend on your assessment of the leak. Also, ensure you change the drain and vent washer everytime you change the oil, to prevent that possible and common entry spot.

Good luck.