Oil Leak

[MrRob]

I went to my boat this weekend and I had it trimed right up as far as it would do and I noticed then a small bit of oil had leaked out of the gear box by one of the filler/breather holes. Is this normal?

[JamesM]

No, drain the oil and check for water, if oil is getting out then water will be getting in. Check the condition of the sealing washers on the filler and breather. If there was only a bit of water in the box then fill it back up with fresh oil and fit new sealing washers. Take it out a couple of times then drain your gearbox and check the oil for water again.

[MrRob]

I havent had it out in the water yet so I dont think there would be any water in the box. I thought it may have leaked out of the breather because it may have been over filled.

[JamesM]

It shouldn't leak it suposed to be water tight. Wipe it clean and then check to see where its coming from. If the engine hasn't been used for a while oil left in the cylinders after the fuel has evaporated can drip out of the exhaust ports and down the inside of the mid section and then run down and off the bottom of the gearbox.

If it is definitely gear oil then drain the oil and replace the sealing washers anyway, fill it back up and then check it after a couple of runs.

[MrRob]

Ahh! the engine had not been run in a while and I thought it looked like engine oil! Come to think about it it could have dripped out of the engine cowl. I wonder.

[JamesM]

If it helps Mercury high performance gear oil (which is ideally what you would have in your box) is a dark greeny/bluey colour.

[MrRob]

ahh, it was a dark bluey colour. Bummer, guess I will have to pop to boat shop on saturday and get some new seals.

[JamesM]

Having said that both normal quicksilver engine oil and mercury high performance blend engine oil are also dark bluey green in colour.

[sinkunit0]

quicksilver gearbox oil has a very distintive smell .esp if its been well used.