CJ2A Operation and Care
Manual -- Proper Maintenance 
(part 8 -- Cold Weather Precautions)

With the approach of cold weather, in regions where the temperature drops below the freezing point, precautions must be taken to prevent freezing of the water in the cooling system.  When water freezes it expands and may burst the radiator and cylinder block.

Be careful to drain the system completely (see Cooling System) when putting up the vehicle in cold weather, unless it is kept in a heated garage or an anti-freeze solution has been added to the water to sufficiently lower the freezing point of the cooling mixture.

It is important that the cooling system be made leak-proof before installing any anti-freeze solution.  Should there be any doubt regarding the condition of either the radiator or heater hoses, replace them.

Common anti-freeze solutions available are alcohol and ethylene glycol.  The distillation or evaporating point of alcohol solution is approximately 170º Fahrenheit.  The operating temperatures of the Jeep when used as a farm tractor and especially when used for belt work through the power take-off is somewhat higher.  As a result, alcohol will not be satisfactory to use as an anti-freeze due to evaporation.  Should it be necessary to use it, the solution must be checked often with a hydrometer to guard against damage due to freezing.  Alcohol is satisfactory for highway use, however is must be checked frequently to make certain that freezing will not occur at anticipated temperatures.

Ethylene glycol has a much higher evaporating point than alcohol, so may be used at higher operating temperatures without loss of the solution.  In a tight cooling system, water only is required to replace evaporation losses, however, any solution lost mechanically through leakage or foaming must be replaced with additional solution.

The capacity of the cooling system is 11 qts.  The following table shows the correct quantity of both alcohol and ethylene glycol for protection at the various temperatures indicated:

30º 1 4/5 0.946 1 4/5 0.946
20º 2 1/8 1 4/5 2.011 2 1 2/3 1.892
10º 3 1/4 2 4/5 3.075 3 2 1/2 2.839
4 1/4 3 3/4 4.022 3 3/4 3 1/8 3.549
-10º 5 4 1/8 4.732 4 1/2 3 3/4 4.258
-20º 5 1/2 4 1/2 5.205 4 3/4 4 4.495
-30º 6 3/4 5 2/3 6.388 5 1/2 4 1/2 5.205
-40º 7 1/4 6 6.861 6 5 5.678
The engine should be operated to thoroughly mix the solution.

In cold weather it is important that a lighter grade of engine oil be used so that the engine may be started easily and to assure an adequate flow of oil to every part of the engine.  Use oil having a low cold test which will not congeal at the temperature to which it will be subjected.

Hard shifting of the transmission gears in cold weather is a positive indication that the transmission lubricant is either too heavy grade or the quality allows it to congeal at the prevailing temperature.  This condition will also probably apply to the transfer case and the differentials.  If the oil is too heavy to allow ease in shifting, it is too heavy to properly lubricate the close fitting parts.  Change the lubricant to a lighter grade without delay.

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