[DeTomaso] radiator fluid- coolant that drops temperature

Dave McManus Dave at DamarDirect.com
Thu Jan 26 10:32:29 EST 2012


Michael, what is your mix?

-----Original Message-----
From: michael at michaelshortt.com [mailto:michaelsavga at gmail.com] 
Sent: Wednesday, January 25, 2012 6:38 PM
To: Julian Kift
Cc: bluebugman2 at sbcglobal.net; De Tomaso List
Subject: Re: [DeTomaso] radiator fluid- coolant that drops temperature

"Water alone is a better coolant than a water -glycol mix"

Are we really going to do all of this again?

OK, here is more info, I stand by my mix, if it's good enough for airplanes,
it's good enough for me.

I watch my car go from 210 to 170 with no other changes other than having
the radiator cleaned and changing the mix.

It runs so cool now that I have put race tape on the grill on trips to keep
it near 180.

Michael


*Coolant Mix and Overheating*
*

The problem:

Sometimes a water-cooled engine such as the Rotax 582 seems to run hotter
than it should, for no apparent reason. An identical engine installed the
same way in another plane may be fine, but one runs hot, and the other
doesn't. This problem can cause no small amount of hand-wringing and head
scratching, but as mysterious as it may seem, it may be quite simple to fix.

Now, more precisely, the situation we're talking about is this: the coolant
temperatures may run up to the 180 - 190 F range as opposed to the more
reasonable 165 -
175 F. Our radiator may be no smaller than someone else's that works just
fine, and the thermostat is not stuck or obstructed. It just runs hot.

The problem might be that the coolant mix is too rich. That is, too much
"antifreeze" and not enough water. And to no one's surprise, what you do to
fix it is take out some of the antifreeze and replace it with water.
Reducing the mix ratio can easily lower the temperature by 15 F.

Why a rich mix gives less cooling:

First of all, in this article, we refer to the stuff you buy simply as
"antifreeze." It comes under many different trade names, and for automotive
applications, is usually ethylene glycol. We'll just call it "antifreeze."

Now if you've ever poured the stuff into a radiator, you no doubt observed
that it is much "syrup-i-er" than water. That is, it has a much higher
viscosity. This means that it will not flow as fast through the system as
water, and the cooling effect will be less.

Further, the specific heat of antifreeze is less than that of water. This
means that for a given temperature change, the antifreeze will carry less
heat each time it circulates from engine to radiator and back.

So, if the mix is too rich, the cooling efficiency will be reduced because
(1) the flow rate is less, and (2) less heat is transferred per cycle of the
coolant.

The manufacturer's recommendation:

The standard recommendation is to use a 50/50 mix of antifreeze and water.
This represents a compromise between cooling efficiency and the ability to
prevent the mix from freezing during cold weather. After all, the initial
purpose of antifreeze is to prevent freezing.

But a 50/50 mix does not give the best cooling. For improved cooling in hot
weather, we should use less antifreeze and more water, perhaps going to a
25/75 or a 20/80 mix ratio.

Everyone knows antifreeze prevents corrosion, and corrosion is bad. True
enough. But, even a 10/90 ratio of antifreeze to water will serve the
puproses of inhibiting corrosion, at least according to one source of
information.

More is better!

Not in this case. When you're adding the coolant to an engine, especially to
an aircraft engine, you want to do it as good as it can be done. Cut no
corners! Don't use just a little if a lot will do. After all, the stuff
coming out of the jug looks high-tech and scientific, and it's expensive, so
it must be good. Therefore, use a lot!

Yes, the stuff is good, high-tech, and all that, but it's physical
properties are not as good as plain, pure water when viewed from the point
of cooling. Therefore, you must resist the temptation to put in more just
because more seems like it should be better.

Results:

Temperature drops ranging from 10 - 15 F are typically obtained by
decreasing the mix from 50/50 down to 25/75 or perhaps 20/80. It is not
possible to give precise numbers here because of uncertainty in knowing
exactly what the initial mix was, and so forth.

In one instance, the original mix in a newly-purchased plane appeared to be
pure antifreeze. When the mix was changed to 25/75, the temperatures dropped
by 20 F! Here's the email that reported the results:

Hi Doc,

Well it worked perfectly and I got a 20 degree reduction in water temp by
decreasing the mix to 25/75. By the looks of the stuff that came out, I
really think that it was full strength antifreeze.

Unfortunately it will not be running any time soon. I had an engine failure
due to a poor gas tank vent design and didn't see a two strand barbwire
fence on the landing. I caught the left landing gear on a post and ripped it
off. Needless to say, the rest is self evident. But then that is another
story.
Thanks Again,
Al


Adjusting the mix, starting from scratch:

Determining the amounts of antifreeze and water is not particularly
difficult if you're filling a completely empty cooling system. The following
amounts are calculated for a system whose total volume is 8 units, whether
pints, liters, quarts, or whatever. (The total volume of a Rotax 582 system
is about 8 pints in typical installations.)

   Mix Ratio         Antifreeze         Water

       50/50                    4                      4
       40/60                 3.2                   4.8
       33/66                 2.6                   5.4
       25/75                 2.0                   6.0
       20/80                 1.6                   6.4
       10/90                 0.8                   7.2

If your system capacity is more than 8 units, say 10 for example, just
multiply each number in the table above by 10/8 = 1.25.

If your system capacity is less than 8 units, say 6 for example, just
multiply each number in the table above by 6/8 = 0.75.

Reducing the mix, starting with a 50/50 mix ratio:

If the system is already filled with coolant, what you must do is drain part
of the mix and replace it with pure water. Based on a system whose total
volume is 8 units, here are the amounts to drain in order to lower the mix
ratio from 50/50:

   New Mix Ratio         Drain and Replace

           40/60                           1.6
           33/66                           2.75
           25/75                           4.0
           20/80                           4.8
           10/90                           6.4

If your system capacity is more or less than 8 units, you can adjust these
numbers the same way as described above.

Reducing the Mix, general case:

This involves draining a fraction of the coolant and replacing it with pure
water as before. The amount to be drained out can be calculated if we know
the mix ratio of the coolant presently in the system and the total system
volume. The calculation is illustrated in the following.

First, express the mix ratio as a percentage, like this:

   Mix Ratio         Percentage

       50/50                   50
       40/60                   40
       25/75                   25       .... and so forth.

We have two different mix ratios to deal with. One is the mix ratio of the
coolant in the system now. We'll call this the OLD mix ratio.

The other is the mix ratio we're trying to get. We'll call it NEW.

The formula for finding how much to drain and replace with water is

   Drain = TotVol x ( 1 -- NEW / OLD )

where Drain is the amount to be drained out, and TotVol is the total volume
of the cooling system.

Example:

Suppose we have a system whose total volume is 10 pints and the mix ratio of
the coolant in it now is 60/40.

That is, it has more antifreeze in it than water. We want to reduce the mix
to 20/80. How much of the coolantshould we drain and replace with water?

   Mix ratios, in percent:         OLD = 60         NEW = 20

   TotVol = 10 pints

   Drain = TotVol x ( 1 -- NEW / OLD )

   = ( 10 pints ) x ( 1 -- 20 / 60 )

      = ( 10 pints ) x ( 1 -- 0.333 ) = ( 10 pints ) x 0.667

      = 6.67 pints

Therefore, if we drain 6.67 pints of the original coolant and replace it
with pure water, the new mix ratio will be 20/80. And that's it.

An obvious final comment:

If you live in an area where the temperatures fall below freezing, you will
need to increase the mix back to a higher value before winter sets in.
Which is to say, you will need the antifreeze to prevent the system from
freezing up. But in cooler weather, it is unlikely that overheating will be
a problem. It would be a shame to forget to change the mix.

Credits: Thanks to my instructor and flying buddy, Mr. Ted Clement, for
sharing this information. He's a gentleman, a scholar, and he doesn't fly
all that bad either.

*


On Wed, Jan 25, 2012 at 6:10 PM, Julian Kift <julian_kift at hotmail.com>wrote:

>
> rDo you have overheating issues? Maybe there is something in the 
> cooling system that requires addressing first? Bear in mind the engine 
> temperature is dictated by the thermostat opening temperature, so if 
> all is well you won't see any decrease in temperature with any of 
> these aids, although cooling efficiency may be improved.
>
> The product may have been No-Rosion? www.no-rosion.com It's a 
> corrosion inhibitor, so does that part of the job that glycol does, 
> but offers no freeze protection. Water alone is a better heat 
> conducter than a water-glycol mix so will aid in cooling.
>
> Julian
>
>
> > Date: Wed, 25 Jan 2012 15:00:54 -0800
> > From: bluebugman2 at sbcglobal.net
> > To: detomaso at realbig.com
> > Subject: [DeTomaso] radiator fluid- coolant that drops temperature
> >
> > Hi guys there was an article a while back that somebody was using
> something
> > like water-wetter but better as they stated in 1 small bottle ( 
> > think it
> was a
> > quart) it dropped the radiator/engine temperature by 15% +, I was
> wondering if
> > anybody new what the name was or the Company
> >
> > thanks in advance Mike #7042
> >
> > thanks Mike V
> >
> >
> > Need an Home Inspection with Thermal Imaging/Infrared 
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-- 







Michael L. Shortt
Savannah, Georgia
www.michaelshortt.com
michael at michaelshortt.com
912-232-9390


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