Date: Sun, 29 Apr 2001 11:39:11 -0500
Reply-To: Joel Walker <jwalker17@earthlink.net>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Joel Walker <jwalker17@earthlink.net>
Organization: not likely
Subject: Re: HELP Flashing red temp light!
Content-Type: text/plain; charset="iso-8859-1"
> Anecdotally, I've been told that certain coolant mixtures become
acidic after
> a year and should be changed annually.
> Sounds like a good geeneric question for the list.
what i've learned from noising around and reading and talking to the
tech folks is this:
antifreeze contains additives, just like motor oil contains additives.
and just like motor oil, those additives get used up ... become
depleted over time. some of the additives in antifreeze prevent
corrosion. some of them lubricate the water pump. in about three years
or 45,000-50,000 miles, those additives are just about used up. the
tech folks at BASF (the folks who make the vw blue phosphate-free
antifreeze. which is, according to them, the same stuff as the
mercedes, porsche, toyota, audi, volvo, and saab antifreeze ... just
different colors for each brand) tell me that the coolant NEEDS to be
replaced every two years, to replenish those additives.
don't believe it? ok, go check on the 18-wheeler trucks. it seems they
have the same problem, different solution: they have a filter on the
coolant system. and on each side of the filter is a valve that they
can shut off (so as to not lose much coolant when they remove the
filter). the filter turns out to be sort of hollow, and in the hollow
space, they put chemical additive sticks. so they can shut off the
truck, turn the valves, yank the filter and put a new filter with new
chemical additive sticks back on the truck, turn the valves again, and
be back on the road in about 30 minutes. they don't have to wait for
the truck to cool overnight like we do. why such a system? cause their
antifreezes are 'guaranteed for 150,000 miles!" ... which is like six
months of driving. and to wait eight hours for the coolant system to
cool down before draining it costs them lots of money.
the point being that coolant, like any other fluid on an automobile or
truck, NEEDS to be replaced. regularly.
the BASF folks also said that the phosphate-free requirement was only
for areas that had hard/high-mineral-content water. with that type of
water, there tend to be precipitates or deposits formed in the cooling
system. possibly in the radiator, but certainly in the bottoms of the
two plastic coolant tanks. at the very least, it 'looks bad'
(according to BASF). they said any ethylene glycol antifreeze would
work fine, IF you replaced it every two years. they were not very
flattering of propylene glycol (possibly since i don't think they make
an antifreeze with it), saying that it didn't handle the ranges of
temperatures that ethylene glycol did. someone on the list said this
wasn't true, but that less of the e.glycol was required (than the
p.glycol) to reach those same extremes.
as i understand it, the coolant consists of antifreeze and water for a
reason:
- the water carries the heat away from the metal parts. water is
better at this job than anything else they've come up with (that can
be found cheaply and in most areas. i kinda doubt that any of us want
to be riding around on top of a liquid sodium metal cooling system,
like some of the early nuclear reactors).
but water freezes. and boils. so they add the antifreeze to lower the
freezing point. it also raises the boiling point, and the engine
becomes useful in most climates. a 50-50 (water to antifreeze) mix is
considered normal. if your temperatures are extreme, either cold or
hot, then the mix can be adjusted to 40-60 or even 30-70, but 30-70 is
the most extreme case i've heard of in an automobile used for general
purposes, in most places where humans live in cities.
the problem with all this is that you mix hot metal and water and you
get rust. so something has to be added to prevent that rust ... and
that's where the additives come in. once the additives are depleted,
there's nothing to prevent the hot metal and water from forming rust.
unca joel
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