15hp Lower unit oil leaks from cast?!

[G8trbait]

Hello again,

I have a 15hp 1988 yamaha 15sg(I believe). I have replaced the lower and upper seals in the lower unit (among other things) AND IT STILL LEAKS! I bought a "fancy" lower unit oil pump from walmart that I screwed into the fill and maxed the amount of oil. The oil is not leaking from either seal, but is leaking from three machined holes just above the vent screw for the lower unit oil. How is this possible? I used the lower unit oil pump to push more oil than it normally holds in order to find where the oil is coming from, which lead to my shock.

Are these some kind of pressure relief holes that need to be resealed? Please help because I am out of options.

Thanks in advance.

 

[99yam40]

Re: 15hp Lower unit oil leaks from cast?!

send some pics, with the lower unit off and point out the holes you are speaking of.

 

[G8trbait]

Re: 15hp Lower unit oil leaks from cast?!

per your request

The holes in question are the two just above the oil level screw. There is another single hole on the other side of the foot that also leaks oil. It just depends on which way i'm leaning the foot to which hole leaks the oil out.

There is another hole above the wash screw but it has what looks to be a rubber stop and doesn't leak oil.

thanks for looking

http://www.facebook.com/photo.php?pid=1868290&l=ec76370de4&id=1050086054

http://www.facebook.com/photo.php?pid=1868289&l=5c80079eed&id=1050086054

 

[cr2k]

Re: 15hp Lower unit oil leaks from cast?!

Those look like the water drain holes. You could have a leak under the water pump base, or it could just be accumlated oil from the exhaust coming out there.

Pressure and Vacuum tests will determine if you have a seal leak.

 

[seahorse5]

Re: 15hp Lower unit oil leaks from cast?!

Inspect the shift rod sealing area also when you pressure test the gearcase.

 

[58rude]

Re: 15hp Lower unit oil leaks from cast?!

I agree, check the shift rod seal. You need to check under the impeller, not sure on yours, but it might have a driveshaft seal under it. Best thing to do now is pressure test it to see where it bubbles.

 

[G8trbait]

Re: 15hp Lower unit oil leaks from cast?!

hmm well when I originally forced the oil out of the "water drain holes" I had the water pump assembly off so the oil also came up and around the gaskets and out the screw holes which bolt on the water pump. Should I try it again with the water pump assembly on?