I just came across this article in the latest (summer 2001) Cams (Confederation of Australian Motor Sport) magazine written by Peter Lawrence. I think it is a excellent overall view of the joys of Glycol coolants. I hope Peter doesn’t mind it being posted here….

Bruce

Glycol Coolants

The use of Glycol-based coolants in circuit vehicles was discussed at the recent meeting of the CAMS Technical Committee.

The use of Ethylene Glycol as a coolant for internal combustion engines arose with the development of the aircraft, early last century (doesn't that sound dreadful, but it is so true). By the middle thirties, aircraft and engine technology had pushed operational altitudes to heights where sub zero atmospheric temperatures had become commonplace, and good old water that had been used in liquid-cooled engines was found wanting. Actually, water was still a great coolant, but ice definitely was not.

Enter Ethylene Glycol.

It was not until the mid seventies that glycol made a serious move into the automotive industry. This was spurred on by the first 'oil shock", when petrol reached enormous prices for the time. Along came the demand for more fuel efficiency, and the use of aluminium in mass-produced cars proved one of the more productive innovations. However, aluminium and water are not good friends, and glycol made it into the service manuals.

Glycol has a number of good things going for it. Firstly, it boils at a higher temperature than water, and freezes at a lower temperature, Moreover, in concentrations over 25%, it is an effective corrosion inhibitor, though let the concentration drop and it actually makes things worse.

However, it is not all-good news. Glycol is around 30% less efficient at removing heat from an engine, which puts cooling systems under greater strain. Fortunately the increasing efficiency of modern engines has resulted in lower heat rejection, balancing out the reduction in efficiency brought about by the use of the glycol.

The other problem with glycol is that as it breaks down chemically, it produces some corrosive by products. The trick is to keep your glycol levels above 30% and change it regularly, generally once a year, though some new additive packages have prolonged the useful life of glycol to nearly three years if the makers' claims are true.

For racing cars, glycol has some problems. Firstly the cooling system on a performance engine is generally under greater strain than that of a road vehicle due to the high heat rejection of a hard working engine.

However, it is not for this reason that CAMS, and the FIA are taking a good look at it The stuff is plain slippery.

Drop water on the track, and it dries quickly Drop glycol on the track, and it dries more slowly, and then leaves a residue which can become like oil the next time it rains. Motorcycling and karting bodies around the world prohibit the use of glycol for this reason, and the bike fraternity in Australia must wonder how wise it is to use tracks like Phillip Island after the cars have been on it.

It is therefore CAMS' intention to move to a complete ban on the use of glycol based coolants for races, though speed events, where road cars are frequent and crashes few will probably be exempt. However, rather than just take the plunge, CAMS would welcome comment on the issue from our members.

Please feel free to have your say by writing to the Technical Manager, CAMS or e-mailing to

<technical@cams.com.au>