Date:         Tue, 28 May 1996 17:40:18 -0500 
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         vwbus@TCPBBS.COM
Subject:      Re: ceramic caotings( was Re: The trans)

TB>   I have been thinking more about the corrosion problem. If you ceramic
TB>coat the heads where they generally corrode, will the corrosion just move on
TB>to somewhere else. Could there be electrolosis at work here?

Hmmn, did I mention this twice before maybe? Sure as shootin corrosion
has
one nature and one nature only, that is electrochemical reaction.  Yep
it
will likely move elsewhere.

  The way it
TB>works in boats is that you install a piece of zink in the outdrive or
TB>transom of the boat. This a sacrificial plate. It just corrodes away and
TB>everything else isn't bothered. I think they put zink plates in the cooling
TB>systems of boats to keep corrosion from the exhaust manifolds (always a
TB>problem) and other places the coolant touches. If we put a zink plate
TB>somewhere in the coolant of the bus would that help?

Hmmn again like I said, this is real common, for body rust prevention
as well, zinc or magnesium should work great, VW used zinc plates on
the body of later cars.  As I have some pure magnesium electrodes in
the 4" x 4" x 15" size range, I'm going to bolt a few bits to the heads
and body of the '85.

TB>    Deisel trucks use different products in the coolant to keep corrosion
TB>and rust away. My neighbor puts Norcool in  his dump truck and when he
TB>84 Vanagon he started useing it in there. He hasn't had the heads off
TB>mi). I understand redline now has something on the market. I belive Bently
TB>says the factory put something into the coolant. I think that is where I
TB>read it. Anybody have any knowlage of additives? 

Once again I talk only to myself, Redline Water Wetter is the product
though
this is for a different battle.  Some believe the problem in big
diesels is more
of an erosion due to all the little bubbles on the surfaces in the
water jacket
carrying away metal, I figure it starts this way in the Vanagon then the
electrolysis takes over.  An interesting point to back this up is that
Leonard
at AVP was telling me once that in the 100's of Wasserboxer heads of
various
conditions they have seen, it always appears that the problem DOES NOT
start
at interfaces between the dissimilar materials like it should if
initially electro-
chemical in nature but rather away in the head off by itself and often
the studs are not corroded either.  As the electro-chemical corrosion
is only going to happen between metals of different potential, if it
does not start there, we must look for another reason.  All big trucks
to my understanding use such a product plus Redline claims reduced
temps as well.  Goes under $10 for the Redline.

On a related weird subject, are the tranny cases on Vans an
aluminum/magnesium alloy?  The 85's case is corroding away severly, 
particularly under the steel bolts, but all over something (magnesium?)
is 
oxidizing and coming out of the case.  I have seen old bug tranny cases
like this but I mean this is bad, large chunks turning to white oxide
and you
can break em off.  I'm looking for a replacement tranny on the side it
looks
so bad.  Never seen it this bad on any bus tranny though they usually
seem
coated with oil, this relatively leak free box may succumb to
structural failure
the way it looks.

John