Waterless coolant and heater matrix

[ChrisH]

Given that waterless coolant prevents any corrosion and runs without any build up of pressure, it is worth changing over to avoid the heater matrix leaking in the future?

 

As we know, heater matrix failure is not uncommon and a pain the arse to fix - so is it worth the £200 or so it would cost to change it over?

 

Also, it never needs to be changed and will help prevent other hoses bursting

[Mk4Gaz]

Not really to be honest.

 

The system has to be totally drained and dry before waterless coolant can be added. Also, if you happen to have a hose fail or a coolant leak catch you out whilst driving, you can't simply top it up to get home.

 

Any good quality ethylene glycol based coolant, at the correct ratio with deionised water, is perfectly adequate, and will contain corrosion inhibitors to stop rust forming.

If you have rusty looking coolant, it's probably because some mong filled it up with tap water in the past.

 

Easy enough to drain, flush, and refill

 

 

[ChrisH]

The system is fine and clean - its just that without building up any pressure in the system it wont put any strain on the heater matrix so making it less likely to fail in the future - which is a pain if it does.

 

Although I take your point - if you have a problem when out you cant just top it up

[Dnk]

Makes sense regarding the benefit of no pressure, you could always buy a spare gallon and carry it with you incase of needing a top up.

 

You wont need the expansion tank or pressure controlled rad cap either i'd imagine

[ChrisH]

According to the Evans Website

 

http://evanscoolants.co.uk/

 

You can mix water with it in an emergency - however, it looses its advantages the more water you add - so it ends up like normal water coolant and will pressurise the system

[Chris Wilson]

I wouldn't waste the money, the pluses are insignificant to the cost, if the matrix is so bad as imminently likey to leak i would just budget for changing it in the near future. I now have matrices that are actually BETTER than factory, and FAR FAR better than the low tube count, low tube density Ebay ones. I also have one brand new OE matrix.

 

From a thermodynamics expert:

 

Hmmm, about the benefits/drawbacks, I first wanted to complain that this stuff only has a heat capacity of 2.6J/(g * K), while water has 4.2J/(g * K). Water has an exceptionally high value, which makes it a great coolant, while other liquids are normally in the range below 2.4J/(g * K). However, water is usually mixed with anti-freeze, a 1:1 mixture has a value of 3.2J/(g * K). So your liquid isn't that much worse.

However, the liquid has a viscosity of 2000(mPa * s) at -40°C, while the standard 1:1 mixture has about 100(mPa * s), and pure anti-freeze has in the order of 1000(mPa * s). This means the stuff seems to be comparable with pure anti-freeze, though they don't state values for high temperature.

So, since the heat capacity is a little lower and the viscosity much higher, the performance of this product is not as good as of the standard mixture. But it's impossible to say how the performance actually is.

Besides lack of corrosion. I can't see a benefit. May be others can?

About the pressure:

 

Put some water into a closed, air-filled cavity, and heat it. When the temperature rises, more and more water evaporates, and the pressure rises exponentially. At 100°C, there's an overpressure of 1atm w.r.t ambient pressure in the cavity. At 120°C, it's already 2atm. If the cavity is opened now, the pressure expands, and since the water is hotter than 100°C, it will boil over. (physically speaking: The water wants to maintain the over pressure by evaporating as fast as it can)

For the mixture, the values are 0.9atm and 1.4atm, since the boiling point is higher (about 110-115°C)

This product has to be heated to 191°C / 375°F to generate a pressure of 1atm, so the pressure will be much much lower at typical motor temperatures.

Finally, a typical cooling system must be pressure tight to increase the boiling point, since motor temperatures can rise above the boiling point. But this is not necessary for this product. On the other side, the system is made pressure tight, some pressure will develop, but by far not as much as with standard mixture. And when you open the radiator of a very hot engine, the mixture will jump into your face, this product will not.

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Comment:

Are there any indirect benefits of not having pressure (or rather much reduced pressure) in the system? What about water/mixture's propensity for forming steam pockets at hot spots ... does this product alleviate this problem?

Hmm, steam pockets form when the temperature of the hot spot is higher than the boiling point at current pressure. The pressure in the cooling system is limited to about 2atm by a pressure relief valve, so the boiling point of the mixture is about 135°C / 275°F. The boiling point of the product is already much higher at ambient pressure, so steam pockets are less likely to form. If some pressure builds up in the system, the boiling point rises higher...