Introduction: How to Test Coolant Freezing and Boiling Temperatures

By 4DIYers
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Video tutorial on how to test the freezing and boiling temperature of your vehicle's coolant. WHEN REMOVING THE COOLANT SYSTEM'S CAP, ENSURE THAT IT IS COOL ENOUGH SO THE LIQUID WOULDN'T BE UNDER PRESSURE. This is a very important because it determine's the antifreeze (glycol) and water ratio. This allows you to drive in extremely cold climates to prevent your coolant from freezing and also maintains your vehicle's coolant temperature in warmer climates to prevent it from boiling. When adding more antifreeze (glycol), ensure that it is the correct type which meets your vehicle's specifications. As for water, add only distilled water because it does not have any additives which can plug up your coolant system. The antifreeze tester is an inexpensive tool which can be found at any local auto parts store. Some procedures will vary depending on the style of antifreeze tester, please refer to the guidelines on the tester. A premixed coolant will not allow you to adjust the freezing or boiling values. This particular tutorial was done on a 1997 BMW 540i.

Tools/Supplies Needed:

  • antifreeze tester
  • antifreeze
  • distilled water

Step 1: Testing Procedure

Do this procedure when the coolant is cooler to reduce the risk of burning yourself. If you have added antifreeze (glycol) or water recently, ensure that the vehicle has been ran for a longer period of time at normal operating temperate to ensure it is mixed throughout the system. If the coolant isn't mixed throughout the system, you will get an inaccurate reading from your testing area. Remove the vehicle's coolant tank or radiator cap, the hose on the tester may need to be extend, depending on the vehicle you are working on. Insert the hose into the coolant, squeeze the ball, then continue to suck up the liquid. Ensure that the liquid inside the container is around the fill line and tape the container to remove any bubbles. If it appears to low, suck up more coolant, if it's too high, empty some of the coolant. Holding the tester level, allow the needle to settle and take a reading. On this particular model the boiling point is located on one side and the freezing point is located on the other side.

Step 2: Altering the Mixture

If you find there is a low boiling and freezing point, add more antifreeze/glycol. Too much antifreeze/glycol will counteract it's properties and lower the boiling point, so be careful not to add too much. Only use an antifreeze/glycol which meets your vehicle's specifications. For water, only use distilled water as it contains no additives which may jeopardize the reliability of your coolant system.

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