Gear Lube Leak

[Water Hazard]

After receiving my boat back from storage this spring, I noticed that there was a large puddle of gear lube under my 60 horse 2006 Yamaha 4-stroke outboard.

I thought/think the issue was due to some damage that occurred to the lower unit when the storage personnel drug the motor along the pavement, but I am not certain.

As part of the ongoing damage issue, I brought the boat in for service in order to determine the extent of the damage.

The guys at the service center ran a pressure test on the lower unit and said that everything was fine. They claimed that the drain plug was just loose (even though I had tightened it before bringing it in for service).

After I got the motor back home from the service station, the leaking stopped for about two days and then started up again. I tried changing the plastic ring gasket on the lower drain plug, but gear lube kept leaking.

As a side note, at the time that I changed the gasket, I noticed that even with the top plug in, gear lube was draining out of the bottom of the lower unit. I thought if you had the top plug in, a vacuum was formed and the lube would stay in the lower unit.

Anyway, I then tried changing the plastic ring gasket on the plug on the top of the lower unit (thinking that there must be some air getting in there and not allowing a vacuum to form), and the leaking stopped for a day.

I then tilted the motor vertical and it started leaking again out of the lower plug.

Does anyone have any idea of what else I can do to get this leaking to stop!?!

Thank you for any assistance you can provide.

[Orlip]

Did you check the screw itself to make sure there are no dings or debris causing the gasket not to seal tight. Check the gear case side as well.

[Water Hazard]

Orlip-

Along those same lines, here are a couple of additional details:

The first time I went to change the gear lube, that lower drain plug was so tight, I ended up stripping it out. I brought the boat into the service guys and they hit it with an impact screwdriver which loosened it right up.

I bought a new drain plug to replace that one. So this plug is new to August of last year.

When I was changing out the gaskets, the old plastic ring was nearly stuck onto the plug. I had to pry it loose. There also seemed to be metal shavings along the threads of the drain plug.

Could those shavings be from the threads inside the motor? I didn't notice any difficulty screwing/unscrewing the drain plug this year.

Nothing else about the plug jumped out at me as damaged, but I can check again.

[Orlip]

There should be a magnet on the plug to attract shavings from the gear case. If these were on the threads themselves and you had it stuck last year, well I don't want to be a downer here but the oil is coming from somewhere.

How hard did they hit it to break it loose. I guess you will have to clean it up real good and watch it very close to see where it comes from.

[Northlander]

Could it be that it got cross threaded or you have the wrong thread/nut for the plug?

[Water Hazard]

As was mentioned, the plug is magnetized...hence the shavings.

I bought the plug from the dealer/service station that I bought the boat. It didn't leak at all last year with this plug, only since I've gotten it out of storage.

There is no real way to know how hard the storage guys hit it...

[iffy]

I really doubt the storage people could have caused a leak in your lower unit plug. It may have been cross threaded at some point. You could try a fibre instead of a plastic washer. It may seal a bit better. Also, tightening and loosening those plugs with an impact screwdriver is the correct way. Are you sure you are getting it tight enough?

[united jigsticker]

If tightening and loosening these nuts with washers on them with an impact driver is the "CORRECT" way, then 98% of boat users are screwed (no pun intended)

I've never heard of this before, and I am sorry, but I think that's bullcrap.

The gasket serves as both a gasket to prevent leaks and a washer to ensure maintained tightness and friction.

Using an impact drive to tighten this screw down will almost certainly compress the gasket beyond it's usable functionability, and possibly do damage to the lower unit and threads of the drain plug.

Are you certain the lube isn't coming from your water intake vents?

[eurolarva]

I think most lower units are made of aluminum which means if there are metal shavings it is coming from your gears not your lower unit. Maybe the newer ones are metal but I think with electrolisis that they would corrode. Put a rubber oring on the screw and see if it still leaks. Pressure tests can fail because sometimes the drive shaft moving will open the leak when it is next to a seal where an unmoving drive shaft the seal seats better.

[united jigsticker]

Sometimes the seal will seat under pressure causing a false pass on a pressure test.

[Pat K]

united jigsticker

I've never heard of anyone tightening the lower unit plugs with an impact screwdriver, but mechanics have been loosening them with impact screwdrivers for as long as there have been lower unit plugs!

I'm sure more than 2% of boaters that do thier own winterizing own an impact screwdriver and use them once in a while to loosen the plugs.

[Valv]

I would take it to another dealer to have lower unit checked for leaks.

Case is made of aluminum, threads could be damaged but gasket will stop leak. I believe the oil is coming from somewhere else, probably propshaft. Dragging motor on floor does not deform case in a way to damage the plug hole, but propshaft could have been bent due to pressure from prop.

If you don't want to take it to a dealer and wait until they check it, then use boat as usual, if there's a leak water will enter case and you'll see milky oil. There's your proof of leak, have dealer fix it with a new seal kit.

Gear oil is thick it doesn't leak well, if you see a pool of oil it needs to be addressed.

Was dealer same as storage place ?

[Water Hazard]

To answer as many of your questions as possible:

No, the service place is not the same location as the storage place.

I agree that dragging the skeg across the ground more than likely did not cause the leaking, I just find it odd that there wasn't any issues beforehand and now there is. The only thing that happened in between was the dragging issue.

I am 100% certain the oil is gear lube. I have repeatedly cleaned the motor to make sure I can tell exactly where the oil is coming from. Originally, there was enough gear lube leaking that it was falling onto the garage floor. Lately, it is just seeping around the gasket. I can visually see the oil around the screw head. There is typically enough in a 4-8 hour period to come off onto my finger if I wipe the plug.

I don't think there are any problems with the prop shaft. I stored the boat without the prop, so there wasn't any damage to the prop. I inspected the prop shaft and didn't see any dings, scratches, etc.

Last night, I took the drain plug out and compared it to the original drain plug. They matched. I then took out the top plug and pumped the lower unit full of gear lube. I am not impressed with the service station as they told me the unit was full and it took me 18 pumps to get any lube to exit the top hole.

I then put the plugs back in and tightened everything down as hard as I could. That was around 8pm last night. At 5am this morning, there weren't any leaks! I am hoping this latest attempt will solve the problem (knock on wood, fingers crossed...).

If the leak continues, I will bring it into a different service facility.

Thanks for your suggestions.

[brunziej]

I am noticing an oil leak from the prop shaft on my motor. It is very black oil. Before I put into storage, I changed the oil in the lower unit. So the color of the oil tells me that it is the old oil that maybe didn't get completely drained out. It appears to have leaked after I had run the motor in the driveway after just getting it back from storage. After the initial leakage, does not appear to be leaking anymore. Should I be concerned? Do I have a seal issue on the prop shaft?

[Valv]

The black oil you see in exhaust oil, which is leftover/condensation from running a 2 stroke motor.

There's nothing wrong with it, you'll notice it when you tilt motor down

[iffy]

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[united jigsticker]

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[iffy]

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[crappie todd]

I recall once when I was a whippersnapper, my son watched me change the oil in my weed whacker. dang screw was so tight I took a lot of swearing to get that dang thing loose.. The boy grew up and headed to a holiday Inn and emerged as the top young crappie slayer on the lakes of Minnesota.

What does that have to do with anything about a guy changing oil in his lawn mower. makes no sence. its all bull crap I tell yah ! the boy never watched .

[Surface Tension]

A new drain plug and washer shouldn't leak.

Not many guys have the correct size screw driver laying around and you'd be surprised how well they work to get the drain plug tight. The tip should be the same width as the plug and the blade thickness should be in contact with entire slot. Blade edges should be crisp and not rounded over. If theres and rocking at all thats not good. That takes a good sized screw driver with a large handle to get some good torque.

[Genofish]

I had a similar problem. I had a ton of fishing line wrapped around the prop shaft and it sheared the oil seal causing the gear lube to leak out.

How tight to make the nut? How freely should the prop turn?

Thans