anode to protect engine

[MBAKER]

Ive been thinking about this....

In freshwater where corrosion of an aluminum intake might be minimum anyway, Why couldnt you install a magnesium anode pipe plug in the engine cooling system somewhere, like an unused hole on the intake crossover? Sure it may need replaced often (maybe not) because of the size, but wouldnt it offer some protection like the anodes located on the drive? In theory if the drive, to the engine, to the intake, etc is all connected electrically wouldnt the drive anodes provide some protection anyway, an additional anode in the intake would just be additional and at a more point of use location.

 

[Don S]

Re: anode to protect engine

Anodes do not prevent corrosion, they prevent electrolysis. Big difference.

Corrosion is what takes out aluminum manifolds.

 

[MBAKER]

Re: anode to protect engine

I was reading a science article (will have to find it now) about the difference between electrolysis and corrosion. It explained that electroysis was a reaction between 2 metals in contact when supplied with an outside electrical force. Corrosion on the other hand is a reaction betwen 2 dissimlar metals in contact that create their own electrical force. So corrosion is a form of electrolysis, but the result is the same although the effect or speed of the reaction would differ.

 

[Bondo]

Re: anode to protect engine

I was reading a science article (will have to find it now) about the difference between electrolysis and corrosion. It explained that electroysis was a reaction between 2 metals in contact when supplied with an outside electrical force. Corrosion on the other hand is a reaction betwen 2 dissimlar metals in contact that create their own electrical force. So corrosion is a form of electrolysis, but the result is the same although the effect or speed of the reaction would differ.

Ayuh,.... This could be the perfect test bed to find out,....

Try an anode in yer manifold, 'n See what goes away 1st,....

 

[MBAKER]

Re: anode to protect engine

this is the type i was talking about. Obviously for the engine not the heat exchanger since I dont have one.

from boatus website....

Zinc pencils

Heat exchangers, because they are typically a copper alloy, are at risk of galvanic corrosion. To combat this, many heat exchangers are fitted with a zinc "pencil" anode. You will find it (or not) under a brass plug in the exchanger. The pencil is unscrewed from the plug for replacement. Some engines have a similar zinc pencil inside the cooling-water jacket to protect dissimilar metals in the engine. Determine if your engine and heat exchanger are fitted with internal anodes, and if so, check them at least annually. If they are half depleted. . .well, you know.

 

[tpenfield]

Re: anode to protect engine

Here are a couple of links that talk about electrolysis versus galvanic corrosion . . .

Galvanic Corrosion - Or Is It Electrolytic Corrosion? It's Important To Be Able To Tell The Difference.

There is a Difference

Corrosion and Electrolysis as applied to Fiberglass Boats

I would be concerned about an aluminum manifold on an iron engine block . . . salt water would be a real problem, but even fresh water could lead to problems over the years.

My boat had stainless steel exhaust elbows attached to iron manifolds running in fresh water. Normally, iron manifolds would last many, many years in fresh water. However, these manifolds were trashed after 16 years, highly depleted. The stainless steel elbows were (and still are) in great shape. . . galvanic corrosion. My thoughts about aluminum versus iron are similar to the iron versus stainless steel issue. The aluminum is the weaker metal and will give its electrons to the stronger metal (iron).

So, sure . . . add some magnesium to the equation and let it be the weakest metal.

My newly installed fresh water cooling systems have the pencil anodes to present a weak metal in the presence of iron(engine) and copper(heat exchanger)