Lower unit oil leak - 15hp Mariner

[bostonpilot]

Hi,

It appears as though the lower unit on my 15 hp mariner is dripping oil from around the prop. The two new oil seals and O-ring are easily purchased, but I am wondering how much of a nightmare I am facing to replace them. Any advice?

From looking at my repair manual's description, it appears as though I need to go as far as pulling the bearing carrier out to replace the seals and O-ring. Once I do that, have I taken on additional work, or can I stop and that point and then just reinstall the parts that I removed?

Also, the book references a special tool (p/ 91-13664) to remove the bearing carrier, with an alternate method of using the thrust hub. How needed is the tool?

Thanks!

 

[Laddies]

Re: Lower unit oil leak - 15hp Mariner

If the carrier is not stuck the hub will usally remove it.

 

[j_martin]

Re: Lower unit oil leak - 15hp Mariner

Are you sure the oil is gear lube? It could just be excess 2 cycle oil in the exhaust.
Gear lube is sticky and very slippery, and has a unique odor.

hope it helps
John

 

[bostonpilot]

Re: Lower unit oil leak - 15hp Mariner

No, I don't know for sure. Unfortunately, I am handicapped by the motor being 50 miles away at my parent's house since my wife and I live in downtown Boston - I haven't convinced her that outboard repair work in the kitchen is a good idea yet.

It appears as though the unknown substance is very black, oily, slippery, and stinks. I was told it smells like dead fish when I asked, but that could be from some of the sea growth that was on the lower end when I hauled this year.

The material is weeping out from the joint between the prop and casting, aronud the OD of the prop.

What would your best guess be as to the source of the goop?
Is it likely/reasonable that oil in the exhaust would present itself there? (the engine has been running super rich lately)

 

[j_martin]

Re: Lower unit oil leak - 15hp Mariner

Most of the exhaust goes out through the propellor hub. If some goop is left in the path, it'll drip out around the prop. It's a close fit, but not a seal.

Loosen the drain screw on the LU, and let a drop or 2 leak out. If it's milky, or water, you have a bad seal and it needs to be repaired. If it's a dark, relatively clear liquid, get a drop on your finger and smell it.

Now, bloodhound, smell the goop coming from the prop. If it smells the same, it's gear lube. If it smells like burnt oil, it's probably burnt oil.

WARNING...... If you have water in your lower unit and it is allowed to freeze, it will wreck it.

hope it helps
John

 

[bostonpilot]

Re: Lower unit oil leak - 15hp Mariner

Great, thanks. Easy enough to do. Sure would be nice not to open up the lower end if its not needed.