What's this "rock" on the back of my sterndrive and is it supposed to be there ?

[dorrals]

Disregard the black on it as it was silver before I spray painted the sterndrive. It's an omc

There's this rock like bit on the back of one of my Stern drives. You can see in the 3rd pic that it's not on the other sterndrive.

My friend says it's supposed to be there but I'm not buying it because of the difference between the two sterndrives. Can someone explain ? Should try to destroy it with a hammer and take it off ? Keep it ? What is it ?

 

[alldodge]

That's your sacrificial anode and it needs replacing, and the other needs one

And I moved it to OMC maintenance

 

[dorrals]

That's your sacrificial anode and it needs replacing, and the other needs one

And I moved it to OMC maintenance

Thanks for the info and for moving it!

Are these generally easy to get? I noticed this today and the boat is scheduled to go into the water tomorrow . This seems like a difficult thing to install and replace while the boat is under water right?

 

[alldodge]

Thanks for the info and for moving it!

Are these generally easy to get? I noticed this today and the boat is scheduled to go into the water tomorrow . This seems like a difficult thing to install and replace while the boat is under water right?

Difficult to replace in the water, but not that bad because drive tips up. Best to do before it goes in. The material needed depends on what kind of water your in

https://ww2.iboats.com/OMC-Lower-Un...815232--session_id.711288205--view_id.1422598

 

[dorrals]

Difficult to replace in the water, but not that bad because drive tips up. Best to do before it goes in. The material needed depends on what kind of water your in

https://ww2.iboats.com/OMC-Lower-Un...815232--session_id.711288205--view_id.1422598

It's in fresh water. Seems like aluminum is the way to go.

What tells you that it needs replacing? From the bit of reading I've done it looks like it's supposed to corrode away but the one I have actually looks larger than the ones on that page and more like a rock. What's all over it?

 

[alldodge]

It's in fresh water. Seems like aluminum is the way to go.

What tells you that it needs replacing? From the bit of reading I've done it looks like it's supposed to corrode away but the one I have actually looks larger than the ones on that page and more like a rock. What's all over it?

Agree aluminum

Not knowing anything about the boat, the growth leads me to think the OMC system (Mercathode for Merc) is not working. The Anode should be depleting indicating it is saving the drive(s).

This isn't happening so I do wonder why. Maybe @kenny nunez may have an idea

 

[1960 Starflite]

It's in fresh water. Seems like aluminum is the way to go.

I didn't have any luck with Aluminum in or Lake (Buckeye). After two seasons the anode looked new, however the lower unit showed pitting. I changed to Magnesium and get three seasons out of them. No pitting on other unit parts. IMHO

 

[Lou C]

You prob need magnesium and there are 2 other anodes besides that one…a small cube shaped one at the tail end of the outdrive & a rectangular shaped one under the outdrive.
I put a bit of Evinrude gasket sealer on the bolt threads that keeps them from seizing from galvanic corrosion.