interesting coolant stuff

[ian@bluemoon.hplx.net (ian Butler)]

On Mon, 24 Mar 2003, T Berk wrote:

> It's SILICA that is abrasive in old style coolant, it rubs seal to
> death and is prob. the main cause (right up there with stiff belts
> drawn too tight) of weepy waterpumps.

> Check the label of the orange stuff next time; silica free. Prob.
> partly the reason the orange stuff seems to creep out around hoses and
> cause that scabby crust as well.

I believe Dex and other long-life coolants have special detergents that,
more or less like synthetic, have a tendency to "clean things up", which can
involve removing gunk that's keeping the system from leaking.

More importantly, though, green antifreeze contains phosphates, and
phosphates eat aluminum.  It's not a big deal in inline cars like
Sciroccos, but it's a *huge* deal in Vanagons, where coolant sits in the
heads, seeps under the gaskets, and pits/rusts its way right through to the
ground.  Such a serious and expensive problem on those that a lot of
prospective Vanagon buyers won't touch a bus with green coolant in it.

It hasn't concerned me enough to immediately replace the green coolant in my
'roc (not that I've had the stupid thing since November anyway.. grumble)
but it's about due for a flush, and it'll get Dex when I fill it again.

> btw- Yep, water conducts better than coolant, 70/30 water to coolant
> seems like a good nominal minimum.

I believe 70/30 is minimum and 30/70 is maximum.  Supposedly if you go above
30/70, the hot light says "Hello, too much antifreeze!" but I haven't
checked...

ian Butler / ian@bluemoon.hplx.net
'88 Scirocco 16v, '87 Vanagon Syncro GL