Removing lower unit 1974 Merc 115

[richardlee]

I am trying to remove the lower unit to change the impeller. I can loosen the front and 2 side nuts, but cannot figure how to get to the rear bolt. There is a fin under the trim tab that looks like it comes off, but I cannot figure how to remove it. I tried twisting but didn't want to put too much pressure on it. Thanks for any help.

 

[richardlee]

I have done a little more research and looking. This is the trim tab anode that I need to remove. The bolt does appear to have some groves on the edges for a socket to fit on to loosen. I tried a 1/2 inch and it did not work. I also tried a 7/16. 3/8 would be too small. Top of the bolt is flat, so this is not a allen wrench head. Puzzled concerning getting this anode off to access lower unit bolt. thanks for any help

 

[Chris1956]

A thin wall 7/16" socket works on the original bolt. Mercury Replacement bolts could be allen head. DIY replacement bolts could be anything.

Worse comes to worse drill some holes in the zinc until you can see the threads of the bolt holding it on. No with some vicegrips, pull off pieces of zinc until it is gone.

 

[richardlee]

Chris1956, thanks for the tip. Raining hard right now. Will try again when it quits raining.

 

[richardlee]

Tried a 7/16. Didn't quite grab. I tried a 12mm. It grabbed but twisted when I put pressure on it. I may need to drill out the zinc. May need to use needlenose instead of vice grips because of the size of access hole.

 

[sutor623]

This just doesnt sound right. Are you sure that the head of that bolt isnt stripped? They make these cool tools for stripped heads that work really well.

 

[Chris1956]

You did get the two nuts under the antiventilation plate, right? My mistake on that 7/16" socket. Try a 1/4" drive with a 1/2" socket. That should fit, if the bolt is good.