Lower unit oil leaking into bilge

[skyking_22]

Alpha-I, Gen-II
5.7L V-8 EFI
2000 Bayliner Cierra

I just put my engine back in the boat and put the out drive back on. Now all of the gear oil in my reservoir bottle ends up leaking into the bilge. So far I have checked:

The bottle, no leaks.
The hose to the thru-hull fitting & the fitting itself, no leaks.

I just can not find the leak. It appears like it is coming back into the boat through the gimble/shaft area. Is it possible the O-ring on the outdrive oil passage failed?

Thanks,

 

[Don S]

Re: Lower unit oil leaking into bilge

Pull the outdrive and look in the bellows. It's probably full of gear lube and leaking into the bilge.

 

[Bondo]

Re: Lower unit oil leaking into bilge

The bottle, no leaks.
The hose to the thru-hull fitting & the fitting itself, no leaks.

I just can not find the leak. It appears like it is coming back into the boat through the gimble/shaft area. Is it possible the O-ring on the outdrive oil passage failed?

Ayuh,.... I'd sooner think the main inputshaft Seal is Shot....
But,...
Pulling the drive like Don says will give you the Answer...

6 nuts,+ the trim pins are all that's between you,+ the Answer...

 

[skyking_22]

Re: Lower unit oil leaking into bilge

I just pulled the drive and found that the bellows had some milky grey oil in there. So my guess might be as stated above that the bellows went bad.

Here are some pics of what I found.



Tx
Bob

 

[cr2k]

Re: Lower unit oil leaking into bilge

Not the bellows. They only seal out water. The drive input seal seals in the oil.
So if there is oil there it most likely came from the input seal.
But check your bellows too for any holes or tears.

 

[havasuboatman]

Re: Lower unit oil leaking into bilge

Did you check the condition of the oil in the drive it's self? Make sure the drive isn't full of that same milky oil. A leaking bellows wont cause drive oil to leak into the boat or anywhere else. It just destroys (over time) the gimble bearing and U-joints, and eventually sinks your boat. If, on the other hand, you've got a bunch of water inside the drive, that water emulsifies the oil and it loses it's lubricating qualities. Heat builds up fast and can cause the seals on the drive shaft to fail, thus allowing drive oil into the bellows and then into the boat.

 

[rodbolt]

Re: Lower unit oil leaking into bilge

need a better picture of the top of the exhaust passage where the intermediate shift shaft passes through the gimbal housing.
judging from the mud and corrosion arount the shift slide either the intermediate shift shaft seal is leaking and then can leak into the bellows or the bellows is leaking.
what typically happns once water gets inside the drive bellows is it rusts the input shaft seal surface creating a seal leak. from there drive oil exits the upper and collects in the bellows until it runs past the shaft and gimbal bearing into the bilge.
doesnt mater where the water came from,bellows leak,shift shaft leakage that gets past the bellows aft end or a sinking on the trailer.
the results are the same and predictable.

 

[skyking_22]

Re: Lower unit oil leaking into bilge

Thanks for all of the replies. The oil in the lower unit seems as new as when I put it in 2 months ago. I tried putting a light bulb in the bellows and sealed up. I could not see any light coming through that might indicate a leaky bellows. I was wondering since i just changed the outdrive seal 2 months ago, is it possible it was not sealed properly and allowed H2O into the shaft bellows. I think i am fortunate I caught it now as the U-Joints still look brand new and no rust is apparent.

I have decieded to er on the safe side and replace the bellows, and shaft seals while I have it apart.

P.S. the gear oil that ends up in the bildge is always green and not water emulsified, as if it came right out of the bottle.

I did notice that there appears to be a round port on the left side of the upper unit that has a nipple on it and no hose. Is that for the lower unit water pump hose? I found the hose tucked up near the transom as if it were removed once by the dealer that worked on it and put in a raw water thru-hull pump for me.

 

[skyking_22]

Re: Lower unit oil leaking into bilge

Thanks for everyone's help. I ended up replacing the shift shaft seal and bushings, all 3 bellows, shift cable and gear oil through hull fitting (i broke the barb by accident during dis assembly). Got everything back together and all works great.

Now I notice a small gear oil leak coming out of the 2 weep holes on the lower unit by the horizontal fins. Any thoughts? is it possibly time to replace all seals in lower unit?

 

[Don S]

Re: Lower unit oil leaking into bilge

Drain the gear lube. Then pressure test the drive to about 15psi. With a spray bottle of soapy water, check for leaks. When you spray where the leak is, it will blow bubbles. It may be possible to even hear yours if it's quiet.

 

[skyking_22]

Re: Lower unit oil leaking into bilge

I just made the pressure tester I found in the Adult Section and will venture out to conduct my test. Thanks again.

Bob