Leak at Prop Help

[mrking]

Just noticed I have a slow leak coming from the prop area of my 1995 15HP Merc outboard. The liquid is black, so I am assuming gear case oil, correct me if I am wrong.<br /><br />Now I am not an expert an outboards but I do like to maintain my engine.<br /><br />So, is this a serious problem or is it just a seal leak that can be fixed with a new seal in the prop area somewhere?<br /><br />Please help if you can.<br /><br />Regards,<br /><br />Michael

 

[andrewkafp]

Re: Leak at Prop Help

If you don't use the motor regularly and start it up now and then, or don't use it as a main motor, it is most likey only unburnt fuel/oil. The best ways to tell are: <br />1. Smell it... Does it smell like fuel or have the distinctive smell of gear oil ?<br />2. Loosen the L/U Vent screw and remove the bottom fill screw. Let a few ml drip into a glass and check if the gear oil is milky or if there is any water in there.<br />3. If you are convinced it's L/U oil, have it pressure tested. The seals are a pretty major job and you will need to dismantle the gearcase.<br />My Merc used to drip unburnt oil/fuel all the time in the winter when not used much, but now I am using it.. there is not a drop.

 

[mrking]

Re: Leak at Prop Help

Unicorn,<br /><br />Thanks!<br /><br />!) Yeah it smells like fuel and I don't use it all that often - about 12 times a year or so.<br /><br />2) Even though I replaced gear oil mid season (I like to make sure everything is changed more frequetly than neccessary) I checked it anyway. **** , the first 1/8 was all MILKY. I couldn't believe it, so I just changed it. **** , that bugs me.<br /><br />Any ideas where the water comes from to get inside there? As I said, I am no expert. Is there a way to prevent it?

 

[andrewkafp]

Re: Leak at Prop Help

Make sure you replace the small circular washers on both srews (fill and vent) with new ones. That is the main source of water entry. I use Merc bright blue ones so I can see them and they don't roll away when topping up the oil. Obviously, the other source of water entry is damaged seals. Sometimes caused by fishing line around prop. If this is definately the case. You need to basically remove all the geargase components inc prop and shaft (some special tools may be needed) and insert new seals. I got a price here in Aus for a Merc Tech to do it and it is about $500 AUD OR $350 U.S.<br />If you are in Canada, you may wanna talk to TMD at www.themarinedoctor.com

 

[mrking]

Re: Leak at Prop Help

That might explain the water in the case. I've been lazy and didn't replace the rubber seals on the plugs for a couple seasons. Thanks for the wake up call. <br /><br />No line in the prop, so we'll see what happens this comming season (after I replace those plug seals)<br /><br />Youv'e been more than helpfull - thanks.<br /><br />Now could you answer my carb fogging question I posted a littel while ago? <br /><br />Cheers,