Practical Automotive Maintenance: Coolant

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Coolant

12.28

00:00	Coolant, also sometimes called anti-freeze or anti-boil, serves the critical function of regulating engine temperature while providing protection against freezing, boiling and corrosion.
00:11	In concentrated form, this substance is a liquid that consists of approximately 90% base fluid, which is usually an organic compound called ethylene glycol or glycol for short.
00:22	This is followed by an inhibitor package made up of additives, as well as a little water as a byproduct of the additive package.
00:30	Once all of these components are mixed together, we get a coolant that's an almost clear liquid.
00:36	From here, a dye is added to the mixture to make it easy to identify.
00:41	The dye also plays a role in classifying vehicle compatibility.
00:45	It's a common misconception that the color of the coolant is the sole indicator of its specifications.
00:51	While it does play a significant role in this, it's actually the additive package that decides the coolant's application and capabilities.
00:58	Just like oil, we'll be able to find which type is right for our vehicle with the help of an online guide or the owner's manual.
01:05	As we just touched on, the most commonly used base fluid in the industry is glycol.
01:10	This is an organic compound that has both a high boiling point of 197 degrees Celsius and a low freezing point of negative 12 degrees Celsius.
01:19	This temperature range is ideal, considering it's typical to see coolant operating temperatures from 80 to 110 degrees Celsius.
01:27	Depending on the ambient temperature and the components installed, as well as the operating conditions.
01:32	It's worth noting that there are some instances where we may see up to 120 degrees, but this is extremely hot and getting to the point where sustained operation under high load at this temperature is potentially dangerous and indicative of a weakness or problem in the cooling system.
01:48	Basic chemistry teaches us that the boiling point of water is a hundred degrees Celsius with a standard barometric air pressure of 101.3 kPa.
01:57	This means that if we were to run water alone and our system exceeds a hundred degrees, the liquid would boil and start to form steam pockets inside our cooling system.
02:06	This would significantly reduce the fluid's ability to absorb heat from our components, ultimately, causing the engine to overheat.
02:13	This is where pressure, which we'll discuss soon, and the coolant come in.
02:18	Thanks to its high boiling point of 197 degrees, glycol will remain liquid should our cooling system reach temperatures above a hundred degrees Celsius.
02:27	While it does have a very high boiling point, unfortunately, it's not all positives, as glycol also has approximately half the heat capacity and a lower thermal conductivity compared to pure water, meaning it's less effective at removing heat from our engine.
02:43	This is the reason a concentrated coolant is mixed with water before being put to use in our engines.
02:49	The term concentrate simply means that there's no prior water dilution other than the three to five percent added during the manufacturing stage, and it only contains the base fluid with an additive package.
03:02	Coolants are known to be miscible, which means that they're able to mix and form a homogenous mixture when combined with water, without the possibility of these two liquids separating later on.
03:13	So, if we stick to a specific mix of water and coolant, most commonly at a 50-50 ratio, we're able to get the best of both worlds.
03:21	The coolant improves the boiling point of the water, while also maintaining good heat capacity and thermal conductivity, allowing for efficient cooling.
03:30	As we just touched on, pressurizing the cooling system has a big effect on the boiling point of the coolant.
03:36	At an atmospheric pressure of 101.3 kPa, pure water boils at a hundred degrees Celsius, with a standard radiator cap rated at 15 psi, which is about one bar above atmospheric, the boiling point rises to roughly a hundred and twenty degrees Celsius.
03:53	Using a higher rated cap will increase it further, though at a diminishing rate.
03:58	For example, 21 psi or 1.4 bar brings the boiling point to around a hundred and twenty-six degrees Celsius.
04:05	The trade-off is that the greater pressure puts more strain on the cooling system components.
04:09	But when this pressure effect is combined with the naturally higher boiling point of the glycol -based coolants, the result is a much more resilient system.
04:18	We discussed earlier that glycol has a freezing temperature of about minus 12 to minus 17, depending on the purity.
04:26	This helps us with the other end of the spectrum, where vehicles are used in extremely cold climates.
04:31	When mixed with water, a chemical reaction happens, effectively lowering the freezing point of both fluids, forming a new and very freeze -resistant mix, which is very important for vehicles exposed to temperatures below zero degrees Celsius.
04:45	If our system was filled with water alone and exposed to sub-zero temperatures, it would result in the cooling system freezing and becoming a solid block of ice.
04:54	This can be extremely problematic, because as the water freezes, it expands by approximately 9 % in volume.
05:01	This would build up an enormous amount of pressure inside the block and cylinder head, which can cause them to crack.
05:07	We should also note that there are contingencies designed into the blocks to help prevent this from happening, known as freeze or welch plugs.
05:15	These are pressed into the casting reliefs used during the manufacturing process.
05:20	If freezing does occur, these plugs should pop out to relieve the pressure and protect the block from cracking, though it isn't foolproof and some damage can still occur even if the plugs pop out.
05:30	It's also common for aftermarket race engines to be fitted with threaded plugs that prevent them from inadvertently coming out mid-race, though that does mean that if the coolant ever freezes, damage will be highly likely.
05:43	Remember, this applies to engines running water alone in sub-zero temperatures, and is easily avoided by the use of a proper coolant mix.
05:52	The boiling and freezing points of our cooling fluid aren't exactly set in stone and they vary slightly depending on the mix ratio, brand, purity and type of base fluid.
06:02	For example, a 50-50 mixture of water with a caltex glycol based coolant gives us a negative 37 degrees celsius freezing point and 106 degree boiling point.
06:13	If we compare this to a 60-40 mixture favoring coolant, then we see negative 45 degrees freezing point and 127 degree boiling point.
06:23	Brands will typically provide a guide indicating two or more recommended mixture ratios, and their respective temperature ratings, and this can be found in the technical data on the container.
06:34	This is important to know if we plan on mixing our own coolant, and the ratio we choose will depend on our environment, vehicle use, and ambient conditions.
06:42	So, we need to make sure we're familiar with our particular brand and its mix ratios.
06:47	For a deeper dive into a given coolant's temperature ratings, most brands websites include a graph plotting how the percentage of coolant affects the temperatures.
06:57	Pre-mix coolants are also readily available, and this is pretty self-explanatory.
07:02	Pre-mix implies that the coolant concentrate has been pre-diluted with water at a ratio determined by the manufacturer and is ready for immediate use.
07:10	This pre-determined ratio is most commonly 50 -50.
07:14	However, again, it can vary depending on the brand and should be listed on the technical data on the container.
07:19	Earlier in this module, we touched on the use of different additives and trace dyes.
07:24	So, why are there, so many different colors and what do they mean? One reason the dye is added is to improve our ability to see small leaks or seepage.
07:32	It's pretty obvious that a brightly colored fluid will stick out much more easily compared to the nearly transparent coolant before the dye is added.
07:41	Another reason for the coloring is for easy identification and vehicle compatibility based on the additives.
07:47	The two most common types we're likely to see and use are green and red which is sometimes seen as orange or pink depending on the manufacturer.
07:56	Green coolant typically signifies inorganic additive technology or IAT for short.
08:02	This is typically suited to older vehicles and contains silicates and phosphates for corrosion protection.
08:09	Depending on the brand and quality of the additives, this coolant can also have a shorter lifespan compared to the others.
08:15	Red, pink or orange coolant is used in many modern vehicles and usually represents organic acid technology for corrosion protection in place of silicates and phosphates.
08:26	Its acronym is OAT and this coolant usually has a longer lifespan than IAT coolants with major manufacturers like General Motors and many European makes favoring this type.
08:37	Pink, orange and yellow coolants can also indicate hybrid organic acid technology or HOAT for short.
08:46	These are a hybrid of the two coolants we just discussed using organic acids and silicates in combination to offer a balance of protection and lifespan.
08:55	Blue or turquoise coolants can indicate phosphated hybrid organic acid technology or PHOAT.
09:02	These are often borate free which is a requirement for some modern Asian market vehicles such as Nissan, Honda or Hyundai.
09:10	Another color we might see is purple which indicates a PSI OAT coolant which stands for Phosphate and Silicate Organic Acid Technology.
09:20	These coolants meet the most recent requirements for most modern car manufacturers and can be used in any system utilizing an OAT coolant.
09:29	However, manufacturers usually recommend fully flushing a system before using this coolant to avoid cross-contamination.
09:36	If we're ever unsure of which coolant is suitable for our vehicle, it can be found via a fluid guide or in the service manual.
09:43	It's important to check this as the mixing of an IAT and an OAT coolant can cause the fluid to gel and turn into a sludge causing blockages that can result in overheating.
09:55	As we can see, there are many different types of coolants that use the same or similar colors and this is why it's important to know what we're looking at and understand the difference in additives as this is the ultimate decider for the vehicle application.
10:09	This brings us onto the last cooling fluid we're going to discuss known as water wetter.
10:14	This product is a surface active compound or surfactant originally developed by Redline and can lower coolant temperatures by as much as 11 to 18 degrees Celsius while simultaneously providing corrosion protection.
10:27	This additive improves the heat transfer properties of cooling systems by using a higher concentration of surfactant emphasizing the reduction of our water's surface tension.
10:38	This increases surface contact and heat absorption, an effect that's also known as wetting ability.
10:45	Water wetter is versatile enough to be used in various cooling system configurations including both everyday driving and competitive motorsport, particularly in drag racing where rules may force its use.
10:57	This is because glycol is extremely slippery.
11:00	So, if a car using a traditional coolant springs a leak or crashes, the track surface will become seriously compromised.
11:07	With its anti-corrosion properties, water wetter is typically targeted towards hotter climates that see temperatures above freezing as it lacks the anti-freeze properties found in the coolants we previously discussed.
11:19	For vehicles in cold climates, the use of a water wetter is still possible as the additive is compatible with the coolants we've already discussed.
11:28	When used in combination with a glycol-based coolant, the wetting ability is reduced slightly.
11:34	However, it's still improved in comparison to a 50-50 mix of coolant and water with no water wetter.
11:41	Okay, let's summarize.
11:43	Coolant, also commonly known as antifreeze, is primarily made from ethylene glycol, additives, and dye for indication.
11:50	A 50-50 mix with water provides optimal heat transfer and combined with system pressure raises the boiling point.
11:58	Coolants are sold as concentrate or pre-mix, but color alone doesn't guarantee compatibility.
12:04	We should always check the owner's manual or a trusted guide.
12:07	In racing or warm climates, water wetter can be used to enhance cooling by reducing water's surface tension.
12:14	Avoid mixing incompatible coolants, for example inorganic and organic acid types, as this can create a gel-like sludge that clogs the system and causes overheating.