Installing Anodes On Outboard

[ggray]

Does it make sense to smear grease on the bottom side of an anode, and maybe on the threads of the securing bolt, where it will contact the (brushed clean) surface of the lower unit?

Anything to help prevent corrosion that would reduce conductivity. I figure tightening the bolt will squeeze out the grease at the points of contact.

 

[fhhuber]

Nope...

it might be OK to apply something to the bolt threads... like a copper bearing anti-seize compound,but don't mess with the contact between zinc and the mounting point.

 

[Chris1956]

Grease will tend to insulate the anode, which is the opposite of what you want.

Most zinc anodes have the bolts pass thru the outdrive and thread into the anode itself, so if they corrode and break, the anode falls off and you can simply install a new anode.

 

[ggray]

Yes, that's the thing I wonder/worry about. I was counting on the firmly-bolted-down contact, with grease sealing around that point to prevent corrosion that would certainly insulate the "connection".

I just found this:

http://www.w8ji.com/dielectric_grease_vs_conductive_grease.htm

According to this guy, I should wipe a THIN layer of silicone grease --which he says is dielectric--on the back of the anode. A conductive grease (anti seize) could be used but I'm not sure how long that would last under water. Actually, for some years I have been using anti seize on the anode bolt threads thinking the metallic content could help continuity.

 

[fhhuber]

Silicone makes great high voltage wire insulation...

Better to use nothing because anything you use will reduce the conduction.

The nature of the beast is, the zinc will erode down to where it makes contact with the contacting surfaces tending to be the last to corrode.

 

[ggray]

The jury is in...NO grease.

Thanks all!

 

[bruceb58]

Is your boat permanently moored in salt water? Are these in addition to the ones that come with your motor?

 

[dingbat]

I certainly would not be using a copper based anti-seize anywhere near zinc in saltwater.

 

[ggray]

Is your boat permanently moored in salt water? Are these in addition to the ones that come with your motor?

Actually, I'm dealing with more than one boat, and in different waters, salt and brackish, and for one, fresh on occasion..

However, the anodes in question are the ones on the motor (or in one case, the aluminum sail drive leg, which will remain immersed for 2 or 3 years).