Water in gearbox oil

[leezor]

Hi All,

I decided to replace the gearbox oil in my 1996 200hp Yahama and found around 10-20ml of water came out before the oil. So I replaced buth upper seals, gaskets and impellor and refilled it with oil.

Took it for a spin today and drained the oil again, though was no water in there it was a little milky. Am thinking this could be because there was still traces of water in the box.

There is no evidence of oil leaks from the lower seals, so I assume the upper seals where causing the leak.
Other than a cracked gearcase, is there any other way water can enter the gearbox?

Cheers

[blaze]

after replacing the seals did you have it pressure checked as well as vacuum checked. you have seals to keep oil in, they dont keep water out, then you have seals to keep water out but will let oil out. they run back to back. other spots water can get in are the washers on the drain/fill plugs, gear selector shaft.
pressure/vacuum testing is the only way to find the leaks
cheers
blaze

[leezor]

Thanks Blaze, will drop it off to get pressure tested next week. Can they pressure test the lower unit by itself or do i have to take the boat in?

[blaze]

just take the leg because to do it the leg needs to be off
cheers
blaze

[Spaniard_King]

It takes a good flush to get rid of all the milky oil.

Have you checked the prop shaft seal for fishing line, if you do a bit of dredging you may have shift shaft seal issues

cheers

Garry

[Chimo]

Hi Leezor

I've been told that if one puts too much oil in the gearbox its possible to cause a leaky seal due to pressure buildup.

How full did you fill it?

If you fill from the bottom and then loosely put the top bung in (so its not air tight ) you can let a little oil out the bottom before you seal and then tighten the bottom bung.

The other suggestion of fishing line around the shaft that stuffs the seal is another one to double check after the props off cause that a very likely cause too.

If your manaufacturer accepts synthetic oils they are a lot more water tollerant too.

Good luck with it, No doubt we will hear the end of the story soon.

Cheers

Chimo

[leezor]

Hi Gary,

Just took the prop off and had a squiz, no line or signs of leaking oil.

Thanks

[leezor]

Hey Chimo,

I filled it through the top bung, and waited until it stopped dribbling. I used a Valvoline Synthetic oil. I also read on another forum that Synthetic oil tends to hold air and can appear "milky" until it settles. Not sure if there is any truth to it tho.

Cheers,

Lee

[Spaniard_King]

Lee,

I been around Big V6 Gearboxes for over 15 years and synthetic oil does not do them any favors

you will find the spec for your gear box is SAE 90 gearlube.

I have also tried a few different gear lubes and have found Castrol EPX 80w-90 to be a good oil for marine outboard applications. I use this oil in commercial V6 applications with good results. Also all outboard gear boxes should be filled from the bottom drain until oil flows out the top hole NO EXCEPTIONS

cheers

Garry

[leezor]

Thanks for the advise Garry, will get some tomorrow and whack it in from the bottom.

Cheers,

Lee

[BaysideMarine]

Leezor,

Why would you fill the box from the top????? Many people do this but it does not make any sense..... Filling from the bottom dispenses any air in the gearcase.

Fill from the bottom until an air free flow exits the top hole. Plug the top hole then plug the bottom hole....

Buy the appropriate pump tube (they are available for the 1ltr and 10 ltr bottles) and the process is simple.

Cheers