road and workshop
Page 52
If you've noticed an error in this article please click here to report it so we can fix it.
by Handyman
Benchwise cool it (24)
IT IS strange that even today some vehicle owners—including commercial vehicle operators—still regard anti-freeze solution as a bit of a luxury and buy the minimum amount possible, very often of the cheapest on the market—possibly an unnamed "home brew" that is really rather a doubt ful protector against severe frost or extremely low temperatures.
A milkman told me that his three delivery vehicles did not really need antifreeze because, being started up each day around 4.30 am they never really cooled down. He did not consider that anything much could happen during the day, therefore he was not prepared to wrap them up when standing in the street for a big part of the day, and save his money.
No mystery
Experience has proved Many times that this is quite the wrong idea; the very fact that there is a radiator in the cooling system designed to provide a greater cooling surface for the water, is the very reason that protection is needed against the lower temperature. There is no mystery about this, neither is there any latitude for half-measures—as when water freezes at 32 deg F it expands near enough 9 per cent in volume. This expansion will split a castiron cylinder as efficiently as a sledge hammer or explosion. So if a water jacket can be split like this, it is quite obvious that the thin tubes of the radiator stand no chance at all.
To install the anti-freeze in the system correctly for protection below 32deg F, the job should be tackled as follows. With the engine warmed up to a point above its rated thermostat opening, the cooling system, hot water heater and any other accessories should be drained completely and the system flushed out, and if it is a well-used vehicle you should follow the corrective cleansing procedure already outlined in this series.
The amount of anti-freeze required is obtained by consulting the vehicle manual for water capacity and then referring to the anti-freeze manufacturer's table for the quantity for that amount of water and add the required amount of anti-freeze, top up the rest of the way with water but leave an inch or so for expansion when warm. Run the engine at a fast idling speed with the radiator blanked off, in order to get the thermostat fully open and so release any trapped air. Further water can then usually be added to fill the system, less the space for expansion.
This expansion space is quickly determined as if the radiator is checked when cooled down after a journey, the system will have expelled the surplus and the amount apparently short or low is exactly the amount the system needs. To add more is to invite it to be pushed out as the engine warms and the coolant expands.
After introducing the anti-freeze solution and warming up, all hose clips should be given a nip up and the system generally inspected for any sign of leak. Obviously, the protection offered by the normal antifreeze mixture has a limit on it, and the manufacturer will usually inform you how far down the scale it will give protection, and while it will not freeze solid at its own freezing point, it will form into a kind of slush caused by the formulation of tiny crystals in the solution.
Blocked passages If this slush does form at some exceedingly low temperature then it can cause trouble as it will not circulate through the radiator tubes, and will block the passages even with the engine going, as the cooling air is drawn through by the fan will not permit it to thaw out. To operate with slush in the system is to risk severe overheating and the chance of heat-crack damage.
Therefore it always pays to use only these solutions that are recommended to cover an expected frost range; do not buy blind or purely because of some special low-price offer. To maintain anti-freeze at the correct mixture calls for regular testing, at least weekly during the height of winter; a hydrometer is required but it must be one that is designed for testing that type of anti-freeze. Obviously testing should not be carried out immediately after adding either water or solution and to obtain an absolutely correct reading it is recommended that the temperature of the coolant should be brought up to approximately 110deg F.