L/U Zinc Anode

[Yesterday]

I've noticed there is a second set of threads at the prop end of the lower unit casing on my merc 850, outside the spanner nut. I'm wondering if they're there for mounting a zinc anode of sorts? I've tried to find one and nothing seems available, yet it would seem a perfect spot for one. Am I missing out on something here?

 

[CharlieB]

Re: L/U Zinc Anode

with your model and serial #'s look it up at Merc Parts, you can find all factory parts, #'s, availability, and price. Save the part # then check iboats and others for an equiv # part.

The #1 web site for genuine Mercury Mercruiser engines, parts and propellers

 

[Yesterday]

Re: L/U Zinc Anode

Thanks CharlieB.
There is none listed on any of the merc parts diagrams, nor have I ever seen any mounted on any motors. I was thinking it might be more readily available as an after-market thing and was wondering if anyone's ever heard tell of such a thing.

 

[Texasmark]

Re: L/U Zinc Anode

I haven't. Most are mounted just above the AV plate buried in the fore aft section of the mid section, about 1" high and 3" long, and on the bottom of the engine mounting bracket.

Mark

 

[Yesterday]

Re: L/U Zinc Anode

Bottom of the mount? Hmmm will have to look into that! So I wonder then, why the outer set of threads just aft the spanner nut?

 

[Texasmark]

Re: L/U Zinc Anode

Bottom of the mount? Hmmm will have to look into that! So I wonder then, why the outer set of threads just aft the spanner nut?

No earthly idea. I'm assuming that you are referring to the OD of the housing is threaded on the outside. Anything you put there would be in the slip stream reducing performance and you have to ask yourself who put the threads there and how did they get them there.

 

[oldman570]

Re: L/U Zinc Anode

I have seen this on some of the older LU castings as well. From cleanning them up real good I don't belive that it is threaded. It looks more like fine rings cast into that thin section of the houseing to make it stronger ,similar to corragated tin for roofs for added strength, because of the thinness of the casting. As others have stated, most of the sacrafical parts are the trim tabs on the bottom of the Cav plate, or have one mounted on the transom bracket of the motor. JMO
Oldman570

 

[merc850]

Re: L/U Zinc Anode

Those are probably sealing rings, the prop goes inside them and water prevents exhaust gases from going around the outside of the prop.

 

[GA_Boater]

Re: L/U Zinc Anode

You're seeing the threads for the the spanner nut. A fair amount of thread is exposed when the spanner is tightened