Zinc fin tab fell off AGAIN

[crazy charlie]

I have never had this even come close to happening before.I lost my zinc fin tab off of my alpha drive for the second time this year.I cant figure out how.I have replaced these things for the last 20 years on my boats and this one has me baffled.I know it was tight.This time I am going to use something on the threads like rtv silicone to make sure it does not loosen up.I also now have 2 dings in the prop,one from each time I lost the zinc.Has this ever happened to anyone else. charlie

 

[bomar76]

Re: Zinc fin tab fell off AGAIN

I haven't had one fall off but I know it can happen since our newer Baja came minus the tab.<br />Don't use RTV sealant!!!<br />Use Locktite- the official Mercruiser trim tab kits come with it all ready on the bolt.

 

[crazy charlie]

Re: Zinc fin tab fell off AGAIN

Any reason the rtv sealant is no good.I had a v8 mercruiser that had rtv on the manifold bolts and when i had to change the manifolds they came out like butter.Charlie

 

[bomar76]

Re: Zinc fin tab fell off AGAIN

It's sealant, not a thread locker.<br />Two completely different things.<br />Sealant: gasketing material used to keep what's in in and/or what's out out<br />Threadlocker: anerobic adhesive used to keep threaded items from vibrating loose. (ok, you can use it on bearing races and other things too, but that's beside the point)<br />Use RTV sealant aas a differential gasket on your pickup.<br />Use threadlocker to keep the bumper bolts and nuts from vibrating off.

 

[lakeman1999]

Re: Zinc fin tab fell off AGAIN

If you use threadlocker, and want to be able to get it back off, use the blue (releaseable) threadlocker.

 

[crazy charlie]

Re: Zinc fin tab fell off AGAIN

I will give it a try,thanks guys. charlie

 

[ZmOz]

Re: Zinc fin tab fell off AGAIN

I had to cut my trim tab off to fit a different prop...didn't seem to make any difference at all...

 

[crazy charlie]

Re: Zinc fin tab fell off AGAIN

I need mine for the electrolysis in my marina.It is for protection of my drive.Charlie

 

[Ralph 123]

Re: Zinc fin tab fell off AGAIN

They also have the flat type (i.e., with no fin) which I use on my twins for electrolosys. From research I've done, the fin is there to help with torque steer on boats w/o power steering. On boats with power steering the flat (no fin) tabs were recommended. If found this info on Mercs site as I was trying to figure out if I needed the fins. If I find the link I will post it.<br /><br />CC, they fell fast enough and straight enough to hit the prop? Intuitivley that seems odd. You think they fell off while you were ideling?<br /><br />You have twins right? So you lost the tab on the same drive twice? Something sounds odd...

 

[crazy charlie]

Re: Zinc fin tab fell off AGAIN

Ralph,it is all very odd to me.Same side once was odd enough,to happen twice,I just dont know.It is usually tough to get them off at the end of a season,this one doesnt need any help.It must happen at idle speed because each time it fell off only one blade took a hit.I put another one on thursday with some sealant but I will also check the tightness once a week from now on.I have to use the large fin Zinc because I need all the protection I can get where I dock.Next I have to remove the prop and hammer out the dings in the two blades.Tough to do hanging off the back edge of the swim platform. charlie

 

[rodbolt]

Re: Zinc fin tab fell off AGAIN

hello<br /> I use loctite 271 on the tab bolts of all yamaha and merc bolts. the bolt is big enough to handle the torque reqired to remove it and 271 does not let go easy. the problem I have seen is the zinc corrodes away from the housing and leaves the bolt loose. not long after the zinc falls off all by itsef.

 

[Ralph 123]

Re: Zinc fin tab fell off AGAIN

CC when is the last time allignment was checked on the drive? It almost sound like excess vibration in that drive for some reason shking it lose... just a thought

 

[lakeman1999]

Re: Zinc fin tab fell off AGAIN

When I pulled my pontoon out for hull cleaning the last time, I found my trim tab was missing, and had to replace it. I just figured, it was doing it's thing, and as rodbolt says, it erodes away (which is it's purpose) in a way, that it loosens it. I think I will remofe them on all of my motors, and use removable threadlocker to replace them. The important thing is to see that they have a very good contact with the motor proper, like a good ground connection.

 

[crazy charlie]

Re: Zinc fin tab fell off AGAIN

This is my first year with this boat and when we got it the zincs were on so i dont think there is an alignment problem.I will look into the excessive electrolysis as a potential cause.The trim wires are coroded off the drive as they have been on every i/o i have owned so maybe i will have to disconnect the wire at the guage to eliminate any stray current.For now I will check the tightness once a week. charlie

 

[vidar]

Re: Zinc fin tab fell off AGAIN

hi! the fin viberated loose... you put your boat reverse...the fin pivoted other way.....ding....no fin....

 

[Ralph 123]

Re: Zinc fin tab fell off AGAIN

CC - that sure would do it. That would make me a little nevous though - that seems like a lot of errosion in short order. Is your Marina typically know to be "hot"?<br /><br />I'm sure you'll figure it out one way or the other. <br /><br />I'm kinda sensitive to this topic. Previous owner of my boat let the electrolosys pit the heck out of the outdrives and gimbals. I was dumb and didn't replace the gimbals and transom plates when I had the boat apart and now it seems like I am just waiting for them to fail...so stupid of me...

 

[jimyoung]

Re: Zinc fin tab fell off AGAIN

Loctite is the best threadlocker out there...however if your fastners are Stainless.....be sure to use the Loctite primer, it greatly enhances the chemical properties that make loctite work.

 

[studlymandingo]

Re: Zinc fin tab fell off AGAIN

Talk about strange: When I first got the boat I have now, I heard a slight "clunk" in the stern area. When I got back home, I noticed the tab missing. The noise I heard was the bolt landing in the splashwell! Apparently the hydraulic pressure kicked it up and forward into my splashwell... Glad it wasn't enough force to kick it forward into the back of my noggin!!!​