Anodes

[captain birdseye]

Hi there,
just wondering if anybody knows the cheapest source to get zinc anodes for 2002 merc 60hp fourstroke. Found anodesdirect, but out of stock,seems a bit harder to get when they are not top dollar.Any help appreciated.
Regards

[willk]

I corrode more anodes than anyone I know and I've spent a lot of time searching for bargains. I'd say beware the cheap stuff and go the extra few quid for the real deal. There's a lot of stuff about that look like anodes but aren't what you really need. I mean - "freshwater anodes", srsly?

[captain birdseye]

Cheers for the reply willks. may I ask where you source your anodes from , that's interesting that the cheaper ones don't do the job , would you say its because they are not actually made of zinc? I toyed with the idea of copying the dimensions and having the local blacksmith knock them up.

[willk]

Originally Posted by captain birdseye

Cheers for the reply willks. may I ask where you source your anodes from , that's interesting that the cheaper ones don't do the job , would you say its because they are not actually made of zinc? I toyed with the idea of copying the dimensions and having the local blacksmith knock them up.

I think what I'm saying is that not all anodes are born equal. They aren't the biggest annual cost and yet they have the potential to cost you big money if they fail to be the weakest link. I've seen pukka anodes fail to work because they were a slightly different composition to the others on the engine. My final position is to run "original part" anodes where there are a number of them working in together to provide protection - i.e. on an OBM.

[Pikey Dave]

You also need to check your installation for current leakage. Proper isolation is crucial

[GuyC]

I have bought chunks of zinc anode from Ebay. One of the bits had part of MG Duff cast in it so unless the seller was being very clever, it was probably of reasonable quality.

I then cut it in to the required shape - which was hard work with a hacksaw. This is probably alright with rectangular shapes but less so with complicated shapes.

Freshwater anodes - these tend to be magnesium as they are as they are about as anodic as you can get but don't fur up like zinc anodes in fresh water. You could use magnesium anodes in salt water but they would almost fizz away in front of your eyes.

Interestingly (possibly), we have just asked MG Duff to specify some anodes for a seagoing steel ship and they have specified aluminium anodes. When I questioned this, they said they were shifting all their commercial customers towards aluminium anodes rather than zinc.

To add to PD's comment, one of the key things is to make sure there is no resistance between the anode and the thing you are trying to protect (before the boat is in the water). Sorry to go off topic.

[jonp]

Don't forget to cheack the powerhead anodes, theses are often small and on the back of stainless bolts in the powerhead. Being small and constantly part of the saltwater cooling system they need changing more often, something many home service handymen forget.

[Pikey Dave]

Originally Posted by GuyC

.......Interestingly (possibly), we have just asked MG Duff to specify some anodes for a seagoing steel ship and they have specified aluminium anodes. When I questioned this, they said they were shifting all their commercial customers towards aluminium anodes rather than zinc.

[emoji106]We've been fitting Ally MG Duff anodes to machines destined for saltwater use for some years now, just as effective, cheaper & MUCH lighter & easier to handle. This is to stainless machines for saltwater use. I don't know how the chemistry would work with fitting Ally anodes to Ally outboards though.

[Maximus]

Originally Posted by jonp

Don't forget to cheack the powerhead anodes, theses are often small and on the back of stainless bolts in the powerhead. Being small and constantly part of the saltwater cooling system they need changing more often, something many home service handymen forget.

Yep that's the ones that'll come back to bite you...if you miss em!!

[Poly]

Originally Posted by Pikey Dave

I don't know how the chemistry would work with fitting Ally anodes to Ally outboards though.

it won't.

[Pikey Dave]

Originally Posted by Poly

it won't.

Didn't think it would, you'd need something more reactive than the ally engine. That's assuming that the engine is pure ally & not a less reactive alloy. The ally anodes are for all intents are "pure".

[beamishken]

All the new mercruiser bravo anodes are manufactured from aluminium
I assume a poorer grade than the drives

[Pikey Dave]

Originally Posted by beamishken

All the new mercruiser bravo anodes are manufactured from aluminium
I assume a poorer grade than the drives

I'm guessing (& am willing to be corrected) that the opposite is true, high purity Ally will be more reactive than the alloy used for the engines, so will sacrifice more readily.

[Poly]

Originally Posted by beamishken

All the new mercruiser bravo anodes are manufactured from aluminium
I assume a poorer grade than the drives

A quick google suggests its an aluminium-indium alloy (which is more reactive than the alloy used in the engine/leg).

[jeffstevens763@g]

https://chem.libretexts.org/Core/Ana...rificial_Anode

For info

[willk]

Originally Posted by Poly

A quick google suggests its an aluminium-indium alloy (which is more reactive than the alloy used in the engine/leg).

Yeah. Right. And when someone slips a pair into yer Yanmar service pack - they sit there, unsullied, the anode equivalent of Highlander, living forever....



It's all about the aluminium now tho.

[captain birdseye]

Plenty info there to keep me buried online.Will check the power head ones though ,that one escaped me . Just ordered the two wedges and the flat plate in zinc for £45 , so we will see how it pans out. Cheers lads
Regards

[beamishken]

Finally got round to servicing the hard boat to go in the water later in the week and took these aluminium anodes off which as you can see have been doing their job
Boat was sat on the mooring for 6 months apart from a few overnights in marinas.
There seemed to be some doubt as to whether they would corrode before the drives but clearly they do

[jeffstevens763@g]

Originally Posted by beamishken

Finally got round to servicing the hard boat to go in the water later in the week and took these aluminium anodes off which as you can see have been doing their job
Boat was sat on the mooring for 6 months apart from a few overnights in marinas.
There seemed to be some doubt as to whether they would corrode before the drives but clearly they do Attachment 119595

Bang on them classic protection