Glycol and cooling system corrosion

[C M Smith <cmsmith@xxxxxxxxxxxxxxx>]

It is the glycol that is highly corrosive. The more glycol you use the more 
corrosive it is. Glycol will hold more heat but its conductivity to heat is 
less than that of water. Glycol also boils at a much higher temperature 
than water. Plain water isn't particularly corrosive but put  even a bit of 
glycol in it and you must use anti corrosion additives or the aluminum will 
be sacrificial to just about any other metal in the engine. Swiss cheese 
water pump impellers, as well as corroded thermostat housings and even 
corroded cylinder heads will result. Needless to say, stock glycol has the 
inhibitors in it, these wear out and are the primary reason to a) use the 
good quality coolant, and b.) flush and refill with fresh glycol at least 
every two years, or at least add the "moose joose" package of inhibitor and 
water pump lube that is available. I prefer to flush and replace on my cars.

Hotter cooling systems allow more efficient cooling, smaller radiators etc, 
as well as allowing the engines to run more efficiently. The objective of a 
good cooling system should be to allow the engine to run as hot as possible 
without damage.

Generally, there is no advantage to using less than 45% glycol in a modern 
street car. You get better performance with up to 60% glycol due to the 
higher boiling point, even though the conductivity will be lower, the 
higher temperature obtainable will lead to better cooling.

If you modify the car to produce more power then that may cause more heat 
loading on the cooling system. However, if you do so by raising the 
compression either by physically changing the ratio or better breathing 
then the existing cooling system should be under less loading than before 
the modifications. If you run higher revs or increase displacement, either 
physically or by supercharging of some kind, then you'll need a bigger 
radiator in all probability.

Cheers


Michael Smith
White 1991 164L
Original owner
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