Evans waterless engine coolant.June 29, 2018
As a reader of the Farm Machinery Digest you are passionate about agriculture and equipment; never satisfied with the status quo — you want your farm to be the best.
Advancements in technology have caused the community to rethink theories that have been long accepted as standard practice. But not much consideration has been given to the liquid we pour into the radiator. That was until Evans Cooling Systems completely rethought the chemistry of cooling an engine.
Before this advanced concept in engine coolant that employs no water can be understood, a review of cooling system basics is in order.
Let it boil (almost)!
It is going to be hard for many to accept that engine coolant on the verge of boiling is a good and proper thing. The caveat being it needs to occur in the cylinder head and not in the radiator.
The dreaded engine boil-over that strands you on the side of the road with the hood open and a cloud of steam emanating from the radiator is what usually comes to mind. That type of boiling is not good.
When boil-over of the radiator occurs it is rooted in the coolant becoming super heated and the radiator’s inability to transfer enough Btu (of heat) (known as rejection) into the air. If this occurs then the coolant starts to boil and expand just as a pot of water would on a kitchen stove.
It is imperative to understand that the job of the liquid is to cool the engine and the function of the radiator is to cool the liquid.
As the liquid passes through the radiator the temperature drops so it can be a heat absorption medium when it is pumped back through the engine. The liquid’s time in the radiator can be consider rest and relaxation as a solider would receive in between combat assignments. If it is not provided the opportunity to drop in temperature during its residence in the radiator, it will possess too much heat to be effective. The liquid will keep absorbing heat from the engine until it can take no more. At that time, it boils and changes phases from a liquid to a gaseous form.
The chemical composition of the liquid along with the operating pressure of the cooling system all impact the temperature the phase change occurs but cannot stop it.
When the coolant boils and becomes a vapor it is ineffective in pulling heat from the engine.
The introduction of the radiator pressure cap by General Motors in the 1930s along with the adoption of glycol based coolants were major advancements in raising the boiling temperature. As an aside, for every one pound of pressure that is added to a cooling system through a pressure cap, the boiling point increases three degrees Fahrenheit.
Altitude has a major influence on lowering the boiling point of a liquid since there is less atmospheric pressure on it.
The misunderstanding of liquid coolant is rooted in the fact that for the most part, the industry monitors the coolant temperature alone and not in conjunction with the metal surface temperature of the combustion chamber. It can be thought of as a mariner receiving directions in latitude without longitude.
The proper method to determine if the engine is in thermal distress is to compare the liquid temperature to the metal surface temperature of the cylinder head. Only then would the picture be clear. If the metal surface temperature is climbing and the liquid reading is not keeping up, then the engine is on the verge of metal over-heating.
As the liquid’s temperature increases its storage ability or in other words, its potential to absorb more heat is diminished. When this occurs the liquid temperature as read on a coolant gauge may appear to be stable, albeit at an elevated temperature, but the metal surface temperature of the combustion chamber and around the exhaust valve skyrockets. This can lead to poor performance and the potential for engine failure.
Thus, the most effective liquid coolant is one that has the ability to absorb a high amount of heat before boiling which will result in the lowest metal temperature in the cylinder head. When the liquid can abstain from boiling and continue to absorb heat there will be more thermal transfer from the cylinder head.
When discussing a cooling system it must be noted that the coolant is also employed to remove heat from the engine block and cylinder walls. Its most challenging assignment though is to control the temperature of the combustion chamber and exhaust valve area.
Different levels of boiling
The load and heat rejection into the liquid are non-linear. It is impacted by many factors. Given a specific engine, the heat rejection required will depend on the operating state.
An engine that is used under light-load will not put much heat into the coolant. This is due to the engine not being required to produce much power. If the same engine is now required to climb a steep hill or pull a trailer, then the load on the liquid coolant increases dramatically.
It is imperative that the cooling system is devoid of any steam bubbles and is a solid stream of liquid. Air is a very poor heat transfer agent when compared to a liquid.
Water-based coolant goes through a number of defined boiling stages as it absorbs heat and prior to becoming steam. These range from nucleate boiling to crisis boiling. When water-based coolant is just on the verge of entering the nucleate stage is when the most heat transfer occurs. When crisis boiling occurs the water-based coolant does little to cool the cylinder head and the metal surface temperature rises rapidly.
The key to proper heat transfer is to allow the coolant to just enter the nucleate stage when the engine is under severe or heavy load. Then have the system pressure move the boiling coolant away from the site, taking the heat along with it and re-condense back to a liquid as it is pushed away.
The cycle of heating, nucleate boiling, release from the site and re-condensing goes on continually in the water jacket of the cylinder head and is responsible for the consumption of the chemical additive package that is included in traditional water-based engine coolant. This is why water-based anti-freeze wears out and needs to be changed or use an SCA. Its ability to stay liquid at low temperature (as long as additional water is not added) is not altered, but the additive package is depleted.
Products that are designed as an engine coolant include anti-corrosion inhibitors along with components to make it more slippery. This is represented using a metric of dynes/centimeter. It is a measure of the surface tension of the coolant. The lower the surface tension the liquid has, the easier it will release from the casting of the water jacket when nucleate boiling occurs. It then re-condenses and removes the necessary heat.
Water-based coolant likes to cling and is stubborn to leave the nucleate boiling site. It will then enter crisis boiling and become worthless as a coolant.
For many years it was believed that water is the best engine coolant since it has a specific heat rating of one, but it is a poor choice. Even if you do not consider the corrosion it causes, the low boiling point (even when used with a radiator cap) and the high surface tension means that it will not do an effective job of removing heat from the cylinder head when compared to an application specific engine coolant — no matter what the dashboard gauge states.
While other areas of engine technology have evolved, water-based engine coolant changed little and still is a mixture of ethylene glycol and water in a 50/50 solution. There is no denying that traditional coolant works —- there are not engines overheated all over the road but a better chemistry was needed.
It can be looked at it in this manner: the old bias- ply tire held air and got the vehicle down the road but it cannot be compared to the performance, wear and overall improvement a modern radial brings. Just think of the Evans coolant as a modern VF farm tire and traditional water-based anti-freeze as a bias-ply design.
The Evans HPC is a non-aqueous blend of glycols that has no water mixed with it. A side benefit of the elimination of the water means that corrosion in the cooling system and engine is completely eliminated. The Evans HPC is a lifetime coolant. A term the industry defines as five years of service.
The real benefit of the Evans waterless chemistry is that it does not boil until 375 degrees F, virtually eliminating any chance of overheating in the radiator. This high boiling point is responsible for a drastic drop in the metal surface temperature of the combustion chamber over traditional water-based coolant when the engine is running, and also during heat soak (shut-off). Since the Evans waterless coolant will refrain from boiling, more heat transfer occurs.
Once the Evans coolant does enter the nucleate stage the fact that it has a much lower surface tension as measured in dynes/centimeter (it is more slippery) means it releases from the water jacket with less system pressure and allows fresh coolant to come in contact with the region.
Due to the unique chemistry the system operating pressure is lower. The Evans waterless coolant builds little vapor pressure. Also, it does not expand at the same rate as conventional water-based coolants nor does it ever freeze.
To convert from traditional coolant to the Evans HPC all that is required is the complete removal of the water-based product and be refilled with the Evans.
Evans Cooling Systems
1 Mountain Road
Suffield, CT 06078