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Date: Thu, 26 May 2005 18:21:08 -0400
From: Ernest Christley <echristley@nc.rr.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Galvanic action (was: radiators as jugs 4)
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David Carter wrote:

>Remaining questions:
>1)  Is the "ground wire" from radiator to negative terminal of battery good
>enough to totally eliminate this "galvanic cell" action?
>
>  
>

You have just made the galvanic cell more pronounced.  It will not eat 
your radiator even faster.

>2)  Forgetting about the type of coolant, and focusing just on the rubber
>donut bottom mounts/isolators from frame, why would that isolation or lack
>thereof alter the "galvanic action" "equation"?
>
>  
>

Goes back to number 1.  The problem is 'dissimillar metals'.  All the 
metal in your engine is getting hit with oxygen all the time.  When the 
metal reacts with the oxygen, we call it corrosion.  It turns out that 
corrosion is an exothermic process, meaning it gives off energy.  Which 
REALLY means that it is going to happen whether you want it to or not.  
The only way to stop it is to hermetically seal it in an oxygenless 
container.

Now, as it turns out, some metals will give off more energy when they 
react with the oxygen than others will.  In fact, if you provide a path 
for the energy to flow, some metals want to react with the oxygen so bad 
that they'll suck the energy out of a neighbor.  The way this energy 
flows in the form of an electrical current.  Whether this energy will 
flow is wholly dependant on the types of metal and their alloying 
structure.  The good news is that the metal piece that had it's energy 
taken away will not be able to react with the oxygen and will last 
forever.  That bad news is that you'll be replacing radiators every 6mos.

Many newer cars use a different type of antifreeze, and the cars carry 
strong warnings against using the old style antifreeze.  The reason is 
the fluids ability to sustain an electrical current. 

>3)  And, I should mention that the Haynes manual shows a bolt in the
>aluminum head for a grounding strap or cable from head to somewhere -
>neither Escort had this bolt/cable, just the empty hole in the head.  Could
>that "have been" or "still be" a problem for my radiator life?
>
>David Carter
>  
>

You didn't have a strap, 'cause the metallurgist who designed the system 
determined that the strap would cause your radiator to get eaten up.  
Don't dare add one.  And take off the one you added.  Or leave it on and 
take careful note of where the corrosion is the most pronounced when you 
replace it 8*).

PS.  You also might want to consider switching to the coolant suggested 
by the manufacturer.  Sounds like the John Deere stuff was designed with 
your car in mind.

-- 
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."