Trim Tab Anode is loose

[bigdogg1]

I think I read this elsewhere (THT perhaps?). I just noticed that my trim tab anode (yamaha 250) is loose. It moves ~ 5 degrees on each side off centre. I took a 12 mm socket and torqued it to 31 ft pounds as per specs and it still moves back and forth.

I read the the bolt that hold these trim tab anodes are also sacrificial and erode away, causing the anode to fall off. Is this correct? The anode bolt does erode, causing the anode it to actually fall off?

If so, I suppose it is time to replace the bolt!

 

[Olde School]

A trusted local mechanic told me to simply use a dab of Sikaflex, or a similar product, between the anticavitation plate and the anode.
This has worked for me all season so far.

 

[gungadin]

Take it off to inspect the bolt, I think it is not an anode so it should be fine. You need contact between the trim tab and the anti-cavitation plate, so use a stainless wire brush and clean the zinc of any build up where it contacts the anti cavitation plate. Clean the bolt threads as well and test fit the bolt to the zinc to make sure the threads are not wallowed out. If the bolt goes in too easily, consider replacing the zinc.Reinstall with a small dab of sikaflex to the correct torque. I have seen the result of the trim tab falling off while underway. Propeller damage and/or a bent shaft is a real possibility.

 

[bigdogg1]

Thanks Gungadin! I just opened this thread back up to update what I had discovered. I had actually just done what you had posted above. I took the zinc and bolt completely off to test fit and they matched perfectly to specs. The anode, however did not sit flush to the cavitation plate until I cleaned it off. Perfect match and fit ... now if I only knew if the trim was set to 0 or 1 or...

Curious about the Sikaflex idea? A dab on the bolt threads? What happens when you try to change it out? Has the corrosion lessened the grip of the Sikaflex by the time it is needed to change?

 

[Goathorns]

Thanks Gungadin! I just opened this thread back up to update what I had discovered. I had actually just done what you had posted above. I took the zinc and bolt completely off to test fit and they matched perfectly to specs. The anode, however did not sit flush to the cavitation plate until I cleaned it off. Perfect match and fit ... now if I only knew if the trim was set to 0 or 1 or...

Curious about the Sikaflex idea? A dab on the bolt threads? What happens when you try to change it out? Has the corrosion lessened the grip of the Sikaflex by the time it is needed to change?

How about some Anti-seize bolt compound. Maintains conductivity, doesn't squeeze out.

 

[gungadin]

As you don't know the setting for the trim tab, I would not use any sikaflex until you get the position set to the correct position. You may not need any at all now that it is cleaned up. If you do use some "a little dab will do ya" and I do mean a very small amount. You need to maintain contact between the trim tab and the engine for it to act as an anode. If you have a good fit between the bolt and the threads, you should not need anything on the threads except a thin layer of grease, to prevent corrosion on the bolt from salt build up.