Holes in lower unit

[HAS]

On a 1975 85hp.Mercury lower unit, there are 3 holes about 1/4 inch dia. Gear oil is leaking
out of the lower hole on the right side. There are 2 holes on the right and 1 on the left. I put new
seals in the lower unit and new water pump. I tried to put up a picture but crashed 3 times.
What do I have to do to fix this leak?

THANKS HAS

 

[Bosunsmate]

Re: Holes in lower unit

You will need to pressure/vacuum test it to see where its leaking
There will be a post on iboats somewhere how to do that.
The seals around the driveshaft can have problems sealing if the driveshaft is pitted worn where they sit.
i fill the pittings with epoxy

 

[merc850]

Re: Holes in lower unit

Those holes are for (Lower- putting gear lube in,(Upper - filling vent for LU,(Flush - for flushing after salt water use. Replace the washers under the screw heads.

 

[HAS]

Re: Holes in lower unit

merc850
These are not the lower unit fill and vent holes, where the screws go, that are on the left (port) side of the engine
On the right (starboard) side of the lower unit are two holes that look to be about 1/4 inch in dia. the one leaking
is a little forware and lower then the other hole.
THANKS HAS

 

[mercurymang]

Re: Holes in lower unit

Got a picture of it?

 

[carholme]

Re: Holes in lower unit

I think the holes you are referring to are more likely 1/8" than 1/4" and are the weep holes, which allow water escape to prevent freezing and rupturing of the case. If it is the most forward hole that is leaking, (generally indicating a shift shaft seal leak) you should drop the LU and see where the oil is gathering.

Gerry

 

[aussieflash]

Re: Holes in lower unit

Those holes are for (Lower- putting gear lube in,(Upper - filling vent for LU,(Flush - for flushing after salt water use. Replace the washers under the screw heads.

LOL...Really....
Do what Gerry said.Plenty of shift shaft seal replacements online.You do need a special tool,or you can make one.

 

[Texasmark]

Re: Holes in lower unit

Has,

How do you know it's gear oil? Why couldn't it be what others have said, just 2 stroke oil combustion residue draining out of the mid section which is normal.

Before I started tearing things apart, I'd verify if I did indeed have a problem.

After your engine has been sitting upright for a few days without running, drop your lower unit drain screw carefully and see what comes out first. No water, no problem. Then check the color. No browns nor milky tints no problem. Then attach your LU oil fill hose and remove the vent screw and pump some more gear lube back into the LU. Did it seem like it was still full, or did it take half dozen pumps to get any out the top? You know there is some space at the top caused by how full you got it last time and how fast you were able to put the drain plug back without much getting around it.

If you answered all the above correctly, quit fiddliing with your stuff and go fishing!!!!! Grin In a couple of weeks or so, go through the LU oil level check I just mentioned and if still full forget it.

Mark

 

[HAS]

Re: Holes in lower unit

THANKS GUYS
Mark it`s new oil leaking from the hole, when I did the water pump. the driveshaft and propshaft seals I should have
put shift shaft seal in also. Gerry you were right, the shift shaft area is full of oil. aussieflash I don`t have the special tool, can
you show me how to make one? THANKS AGAIN CHUCK

 

[carholme]

Re: Holes in lower unit

See this link, post #6:

http://forums.iboats.com/mercury-ma...ng-lower-unit-kill-oil-water-leak-598595.html

Gerry