Re: RedLine Water Wetter Question

[Scott Fisher <sefisher@cisco.com>]

Ah, WaterWetter, a very timely question.  First, the theory, then the
practice, then what I'm doing this week:

1.  Theory: WaterWetter is simply a surfactant, a detergent if you will,
whose purpose is to reduce the surface tension of water.  Why?  Lower
surface tension means smaller bubbles when the water *does* boil, and as
someone pointed out in the discussion on pressurized cooling systems,
the density of liquid water makes it a much more effective cooling agent
than water vapor.  So... coolant with RedLine keeps more liquid water in
contact with the cooling system passage walls than coolant without
RedLine.  As a side benefit, water with WaterWetter (WW) in it is
significantly less slippery than spilled water with ethylene glycol (EG)
in it -- and while this may not seem like a big deal to you and me, it's
a HUGE deal to the corner workers at on-track events and races, who may
get stuck slipping in (or pulling people out of cars that slipped in)
puddles of green slime if your car overheats on course.

2.  Practice: I've used Water Wetter in a selection of older cars, in
particular British sports cars legendary for their tendency to
overheat.  Replacing the coolant with distilled water and Water Wetter
is one of the first things I do with whenever I acquire British (or
Italian) sports cars.  It drops the operating temperature noticeably,
reduces boil-over, and keeps the car running happily in California
100-degree-plus summer temperatures.  And it keeps my friends, the SCCA
corner workers, happy just to know I'm thinking of them when I go out on
track (which I'm getting ready to do again in about three weeks, if all
goes well...)  I also drain part of it in winter and add 40% or so of a
propylene glycol coolant such as Sierra, which is environmentally
friendly, as British sports cars tend not to have closed cooling systems
so if I'm going to spew glycol vapors (and occasionally liquid) while
motoring, I might as well spew something that's not toxic.

So... about three weeks ago I drained the who-knew-how-old coolant in my
recently purchased '83 GT Coupe and replaced it with distilled water and
WaterWetter.  For the first week or so, everything seemed to go well --
it was very hot, and even in the hottest weather the coolant stayed in
the middle of the range.

Then things got weird.  On my way to Laguna Seca, ambient temp 65
degrees F, traffic about 65 mph, I noticed the needle quite a bit higher
than the middle -- still below the top mark but higher than it was when
the ambient was 95.  What the...?  Sitting in traffic the temp dropped,
then jumped back up on the road.  As a side note: my radiator temp
switch is stuck closed, so the fan runs when the key is in the ON
position.  This, I believe, is important.

I talked this over with the smartest car-guys I know, one of whom
wondered whether -- between the RedLine and the stuck fan -- I was
cooling the water in the radiator TOO much.  "Of course, that'd only
work if you had a reverse-flow system, where the thermostat is connected
to the bottom of the radiator."  What kind of nincompoop would design a
system like that? I asked.

Ah.  The Geniuses (see list of TLAs) at Audi, obviously.  Sure enough,
this is what I think happened:

a.  The coolant heats up in the engine and flows without restriction
into the top of the radiator.

b.  The constant-running fan cools it down below the point at which the
thermostat opens.

c.  The thermostat stays closed, causing the temp inside the engine to
rise.

d.  The water in the TOP of the radiator gets Really Hot.

e.  The TOP of the radiator is where the relief line to the coolant
overflow tank is located.

f.  Steam and hot coolant spews into the overflow tank and, in extreme
cases, out of the cap.

g.  This reduces the coolant *in* the engine to the point where it heats
up *more*.

h.  Meanwhile, the cold coolant on the upstream side of the thermostat
acts like a heat sink down there and it never f&*@%!ing opens, causing a
self-accelerating loop of steps f. and g.

So... I did two things, but that's Step 3:

3.  This Week:  Well, actually, last Thursday I wired in a switch across
the terminals of the fan relay so I could *simulate* the operation of
the temp switch on the radiator & determine whether it was in fact
causing my weird thermal runaway problem.

Short answer: it was.  As long as I watch the gauge like a hawk and turn
off the fan when I'm on the freeway or otherwise have airflow over about
50-60 mph, it never gets over the top tick on the little faux
thermometer at the side of the gauge, and most of the time will stay in
the middle of the little faux thermometer.  ANd then when I pull off the
freeway (or get stuck in stop-and-go traffic) and the needle climbs a
bit, I switch the fan on and the temp drops.  Groovy (and you thought I
was going to say cool, didn't you?)  

So my wife, later today, is picking up the temp switch from Linda at
Carlsen, for $8 and change, along with a new fuel pump relay of the
appropriate setting for a 5-cylinder (all these months I've been using a
manual switch, feels just like a race car! :-).  I also instructed her
to pick up a new cap for the overflow tank, and also some of whatever
foo-foo Audi-specific coolant Linda recommends.  

The way I see it, this cooling system is designed backwards from any
other that I'm used to, with the result that the mods I typically make
cause the opposite effect.  So I'm going to go with the Official Factory
Foo-foo Recommendation.

That being said, I'm sure I'll have a little WaterWetter in the mix of
Official Audi Foo-foo Coolant and water that I put in this weekend, if
only because I won't have completely drained the engine, heater etc.
when I pull the switch from the bottom of the radiator and let all the
existing crud spew onto the driveway where it will enter the bay and
poison waterfowl.  (Hey, just joking, it's clear water in there now,
remember, that's the problem...)  

I'll let y'all know (perhaps a little more succinctly) about cooling
system performance after I get the system configured in its intended
manner, but at this point, I believe that I'll omit the RedLine WW from
the Official Audi Foo-foo Coolant mix I put in this weekend.

--Scott