This test is done by using a refractometer engine coolant tester. Refractometers test for the amount of glycol in a coolant mixture by measuring the speed of light as light passes through the fluid and is not affected by the specific gravity of the glycol. Refer to Coolant Concentration Testing .

Tools Required

Important: 

•	Both J 23688 and J 26568 automatically compensate for temperature.

•	Before each use, swing back the plastic cover at the slanted end of the coolant tester, exposing the measuring window and the bottom of the plastic cover.

•	Wipe the measuring window dry with a tissue or a clean, soft cloth.

•	Close the plastic cover.

1. Release the tip of the pump from the housing of the J 23688 or the J 26568 .
2. Do not remove the clear plastic pump from the J 23688 or the J 26568 .

Caution: As long as there is pressure in the cooling system, the temperature can be considerably higher than the boiling temperature of the solution in the radiator without causing the solution to boil. Removal of the pressure cap while the engine is hot and pressure is high will cause the solution to boil instantaneously -- possibly with explosive force -- spewing the solution over the engine, fenders and the person removing the cap.

3. Remove the surge tank/radiator cap.



4. Insert the tip of the pump into the surge tank/radiator. The tip of the pump must be below the level of the coolant.
5. Press the bulb. Release the pump bulb in order to obtain a sample of the coolant.
6. Bend the tube around the J 23688 or the J 26568 . Insert the tip of the pump into the cover plate opening.
7. Press the pump bulb. Allow a few drops to fall onto the measuring surface. Do not open the plastic cover when taking readings because any water evaporation will change the reading.



8. Point the coolant concentration tester toward any light source. Look into the eyepiece.

•	The coolant protection reading is at the point where the dividing line between light and dark crosses the scale. Antifreeze protection is the scale on the right.

•	The temperature scale is reversed from a standard thermometer scale. Below zero readings are on the upper half of the scale.




9. If the readings are not clear, properly clean and dry the measuring surface. Conduct a new test. Make sure there is enough fluid on the measuring surface.

J 23688 and J 26568 are factory calibrated and sealed. The testers should not require adjustment. If adjustment is required, refer to the tool manufacturers recommendations.