Anode bolts broken inside threading; threading also worn

[capslock118]

The issue occurred on a mercury engine but I wouldn't say this issue is mercury specific so I posted in the general forum.

During my spring tune-up I went to replace the anodes on the engine. I've owned the boat for 2 years and never replaced the anodes (1990 boat). It looks like the trim anode had not been replaced in years. Oddly, the trim tab anode looked fine.

Anyways as I went to install the trim anode i found out that the bolts from the old anode had broken some time ago and now half of the bolts on each side is stuck inside the threading of the anode mount.

I tried to use a screw extractor with no luck and the threads look terrible anyways; as if no threads even exist.

I am going to speak with my local mercury repair shop and see what they have to say. Before that, I am wondering if anyone here ever came across this issue before and what you did to resolve it?

I am thinking at worst they will have to extract the bolts in some way I cannot and then use a tap and die set to set new threads in the mounts and I will just have to use large bolts next time around.

Note, this is the anode that goes under the trim block that makes the engine trim up/down, not the trim tab that is mounted just above the prop.

I doubt it would be safe to put the boat in the water before this get's fixed? I have the boat sit in a slip all season.

Thanks for your input.

 

[Chris1956]

Re: Anode bolts broken inside threading; threading also worn

There are other ways to get the anode's protection. You may mount another anode on any part of the motor that is underwater all the time. Perhaps the transom bolts are underwater while at rest in the slip? If so, how about installing anodes on the transom bolt ends? They make some specifically designed for that useage. As long as you have electrical continuity to the PTT unit, you will be fine. You could also bolt an anode thru one of the unused trim rod holes, as well, if you can install it so it doesn't intefere with trim movement.

 

[capslock118]

Re: Anode bolts broken inside threading; threading also worn

Hi Chris,

Interesting solutions; I'll certainly consider them before replacing the trim assembly; thats my worst case scenario.

the transom bolts are underwater while at rest in the slip? If so, how about installing anodes on the transom bolt ends?

The engine is lifted entirely out of the water while at rest in the slip. The only parts that sit in the water while at rest is the transom and a bit of the power trim assembly that sits within it.

 

[Chris1956]

Re: Anode bolts broken inside threading; threading also worn

Aren't your bottom transom bolts in the water at rest?

If not, how about connecting a stainless eyebolt to a chunk of zinc anode, and bolting the eye of the bolt to the lower transom bolt, with a second nut and washer?

Heck you could also slip that eyebolt onto the tilt rod, as long as it doesn't contact the triple clamp when you trim down. It might bang around a bit, however.