Date:         Thu, 25 Nov 1999 12:08:46 -0800
Reply-To:     daveb@CP.NET
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Dave Bayer <daveb@CP.NET>
Subject:      Re: Wasserleaker Head Job - What am I getting myself in for
Content-Type: text/plain; charset=us-ascii

> If I see also they use polypropalene
> glycol, I know they are not associated with spec fluid or don't much care
> about spec. It is proof I should not trust their engineering sence. They
> don't know, and they don't care that they don't know. I will validate what
> I can of their work.

        Hrm, polypropalene gycol, AFAIK, came out (in mass quantities)
after VW had stopped importing VWs. From the research I have done,
poly... gycol can transport 10% to 15% less heat than ethylene gycol,
however both are far inferior in the amount of heat each can carry
compared to the water in the system. This isn't going to even be
a consideration unless your van is running in high temperatures at
slow speeds and/or high loads when the engine is producing max
waste heat and you are both circulating low volumes of coolant and
you have less of a thermal gradient between outside air cooling air
and the temp of the coolant in your radiator... I should also
like to remind folks that VW loves to reuse parts... People like
to say that's because they care about us, but I would venture
is more because they like to stay with what they think works and
what is cheaper for them (retooling doesn't sound cheap)...

        I should like to refer one interested in the study of the
coolant system to a post by Tim Smith, search for 'crevice corrosion'
if you would like to answer the one question that no one seems to
have a good answer to (besides Tim Smith ;)):
        Why do the heads pit so much quickier under the gasket than
        over the surface of the head exposed to the damaging coolant
        (if said surface pits at all)?

        I should refer others on the topic of proplyene gycol to
a post from the 96ish time frame with 'Green Stuff Considered -
Coolants and Corrosion'. It was a good discussion/jumping in point
for the discussion of coolant, coolant additives, and how each
affects the different metals in your engine...

        And then there is a bunch of good research in the file
archives on gerry by Dan Houg (some of it from talking with
technicians at BASF - the people who make 'VW' coolant:
ftp://gerry.vanagon.com/pub/technical/coolant-some-info-for-watercoolers-1983-and-later.txt

And hey, while your there, poke about the file archives, there's
LOTS of good tech info and procedures there (including two
different write ups on how to replace the head gaskets with
and good insights for the lay mechanic who might overlook doing
certain things before it's too late).

dave