Water free antifreeze

[Vanbursta]

I am thinking of switching to water free antifreeze, does anyone have experience with this? Part of the reason I am considering it is that because it's water free, there is never any pressure generated in the system so less chance of leaks etc, on the negative side it is expensive to do and I don't know how long it will last before needing replacement.

[chipsceola]

Recent discussion on this 'Waterless Coolant' and this post from T-Cut most relevant to what I think you are asking.

[Doc Evil]

I could be wrong, but I think you will find it still expands when hot as the molecules move apart when heated therefore expansion and subsequent pressure as its volume increases in a finite vessel!
Whether it expands as much as water though I couldnt say if so reduced pressure , its very expensive my personal prefference is make sure your cooling system is functioning 100% and use deionised water with your choice of good quality antifreeze
No problems
Have I now opened a can of worms?
Doc

[T-Cut]

It's primarily vapour pressure that 'pressurises' the cooling system. The volumetric expansion of the liquid is of little significance. So, since standard coolant mix boils around 108C at atmospheric pressure, its vapour creates 15psi at that temperature. To blow the pressure cap relief valve requires around 22psi. This means a coolant temperature well above 130C.

The waterless coolant is propylene glycol which has only one tenth the vapour pressure of water. This means under typical running conditions, there's almost no pressure in the cooling system. Only the air standing in the expansion tank will develop a little pressure as it warms.

TC

[ChestersDad]

One of the probs with using standard water mix is internal corossion as it ages - has that been negated by waterless?

Another thought is whether the pumping system and pump vanes are able to maintain the same flow rate if there's a diffo fluid resistance?

[T-Cut]

Originally Posted by ChestersDad

One of the probs with using standard water mix is internal corrosion as it ages - has that been negated by waterless?

Corrosion of any coolant system will not/should not happen if it is renewed as recommended by the manufacturer. All antifreezes contain corrosion inhibitors (along with several other things) that prevent metal corrosion over the scheduled period. Waterless coolant also contains inhibitors, not only against corrosion, but also to counter the effects of thermal degradation of the stuff itself. Propylene glycol degrades over time with continued high temperatures. Everything has a life span.

Another thought is whether the pumping system and pump vanes are able to maintain the same flow rate if there's a diffo fluid resistance?

The viscosity of waterless coolant and standard coolant is certainly different and has a different viscosity-temperature relationship. Cars are fitted with pumps designed to circulate standard coolant so in some instances may not be reliable when pumping fluid of a different viscosity. Some engines have an alternative pump fitted when used in sealed-for-life/waterless cooling situations. This is typically in the trucking industry around the most northerly regions of the world.

TC

[bear-mg]

I just google'd this and found some info on the Evan's waterless coolant website , it sounds abit expensive at first but in the long run you should save money due to never needing to replace it , it mentions using a prep fluid to remove all traces of water and coolant from the system prior to the waterless conversion , got me thinking that due to the lower operating pressure characteristics this stuff should in theory help prolong the head gasket due to lower pressure and no corrosion which you would find in a conventional water filled system , sounds to good to be true

[Doc Evil]

M

Originally Posted by T-Cut

It's primarily vapour pressure that 'pressurises' the cooling system. The volumetric expansion of the liquid is of little significance. So, since standard coolant mix boils around 108C at atmospheric pressure, its vapour creates 15psi at that temperature. To blow the pressure cap relief valve requires around 22psi. This means a coolant temperature well above 130C.

The waterless coolant is propylene glycol which has only one tenth the vapour pressure of water. This means under typical running conditions, there's almost no pressure in the cooling system. Only the air standing in the expansion tank will develop a little pressure as it warms.

TC

fll

Sorry TC maybe im being a bit thick but as the system is pressureised it raises the boilling point of the coolant beyond its normal operating temp range therefore remaining a liquid with a larger volume
Doc

[T-Cut]

The volumetric expansion doesn't cause the pressure to rise very much. As the level rises in the header tank, the air inside is compressed slightly. With a waterless coolant, that's more or less it. With a water based coolant the same thing happens of course, but water vapour is also generated because of the higher volatility (low boiling point) of water. The vapour pressure is what creates the figures we see. For example,the relief valve pressure of 22 psi (140kPa).

All liquids boil when their vapour pressure equals the surrounding (atmospheric) pressure. If the surroundings are sealed (as in a cooling system), the liquid will continue to heat up without boiling. When its vapour pressure finally reaches the cap pressure, the cap opens and the liquid boils.

Think about this. What happens if some water is sealed inside a glass or steel ampule, with no escape for the vapour. The container is about half full. You heat the ampule over a flame. What happens inside?

TC