January 19, 2017
Most people assume that the role of antifreeze is just that: to protect engines from freezing in the colder months of the year. But antifreeze performs numerous other roles year-round.
Not only does antifreeze prevent freezing and expansion of the cooling circuit that can lead to damage in normal operation, it also assists in raising the boiling point in conjunction with the pressurised system produced by the radiator cap.
As many OEMs have raised the operating temperatures of engines in an effort to reduce emissions, the strains on the cooling system have also increased. We therefore need to maintain a careful balance of the main components of antifreeze, glycol and water. If the ratio is too high, in water the anti-freeze protection and anti-boil properties are reduced. If the glycol level is too high, it can also reduce the anti-boil, reducing the heat transfer properties of the cooling system leading to the chance of overheating the engine due to insufficient heat removal. If all the ratios are maintained with a glycol level normally between 33% to 50%, we are half way there.
The next points to consider are the additives and the way they function.
A traditional formulation will slowly build a protective layer on the surfaces of metal components in the cooling system to prevent damage from electrolysis and cavitation. The downside to this formulation is that it can reduce heat transfer through this protective layer and can also affect temperature readings on electronic sensors. This can lead to the vehicle believing the cooling system and engine are running colder, leaving the vehicle to run in its cold cycle mode longer using more fuel and affecting emissions. The point at which cooling fans are also triggered can also be adversely affected, potentially leading to over- heating.
A solution is available from new formulations commonly referred to as ‘long life’ or ‘organic’ coolants, which react chemically with the metal surfaces on an ‘as required’ basis to protect the system without the build-up. These additives have a longer service life compared to the traditional types lasting on average for five years compared with the traditional two years.
With maintenance costs, disposal costs and correct system operation, traditional type coolants have very little place in the modern workshop.
Mixing of concentrate and water is the normal method employed by most workshops. Care should be taken that this is carried out correctly as the coolants should be mechanically mixed with good quality water. Placing the concentrate and water into the cooling system and allowing the water pump to mix is the easiest option. If top-ups are required, this should also be done using the correct ratios. For ease, most products are now available in a premixed ready-to-use form to save any incorrect mix ratios.
We have seen practices of concentrate coolant drums purchased and then half the contents placed into a spare drum then both filled using the closest water supply, normally the garden hose. These can then sit for a period of time before use without being mechanically mixed. The glycol being heavier than water, if not thoroughly mixed will often separate to the bottom of the drum causing major application issues. If the entire drum was to be used in one cooling system we would have little trouble, but as most would be placed into several different systems, the first half of the drum normally pumped from the bottom would show concentration levels around 75% glycol and the second half of the drum showing 25% glycol. As these are outside of recommendations the different concentrations can lead to problems as discussed earlier.
Tips for best practice
- Where possible look to a premixed version for use and top-ups.
- Ensure concentration levels are maintained checking with a hydrometer or refractometer.
- Check pH level after concentration to check condition of coolant, referring to manufacturers specifications.
If in doubt contact your technical department for assistance or call the team at Oil Intel – 0800 TOTAL OIL (868 256).